USE OF FILLED POLYMERS FOR STRUCTURAL APPLICATIONS By WOLFGANG RYOR A THESIS PRESENTED TO THE GRADUATE SCHOOL OF THE UNIVERSITY OF FLORIDA IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE DEGREE OF MASTER OF SCIENCE IN CONSTRUCTION MANAGEMENT UNIVERSITY OF FLORIDA 2018
2018 Wolfgang Ryor
3 ACKNOWLEDGMENTS First, I would be remiss without acknowledging my parents who as professional educators instilled within me the pursuit of academic goals. Sev eral people were integral to the completion of the foregoing research Grateful appreciation to Dr. Nancy Ruzycki who was invaluable as a guide through technical and conceptual difficulties. Many thanks are also owed to the staff and entire department of m aterials engineering at the University of Florida. Testing would not have been possible without their help. Speaking of testing, thank you to Ebenezer Tackey Otoo, who provided his research and spent many hours explaining various mixtures. A special nod, a lso, to Dr. Chelsea Simmons. The idea for this thesis was born in her mechanics class. Strain gauge guru, Dr. Peter Ifju, gave his time to educate the author regarding the operation of those essential tools. Professor Michael Cook helped with materials est like to thank my chair, Dr. Larry Muszynski, and my committee, Dr. Raymond Issa and Dr. Russell Walters. I have often interrupted their busy schedules to seek their advice. Finally, Wendy Thornton has been superb as editor of this manuscript.
4 TABLE OF CONTENTS page ACKNOWLEDGMENTS ................................ ................................ ................................ ............... 3 LIST OF TABLES ................................ ................................ ................................ ........................... 6 LIST OF FIGURES ................................ ................................ ................................ ......................... 7 ABSTRACT ................................ ................................ ................................ ................................ ..... 8 CHAPTER 1 A FLORIDA EXPERIMENT ................................ ................................ ................................ 10 Conceptualizing the Phenomenon of Change ................................ ................................ ......... 12 Employing the Means of Change ................................ ................................ ........................... 14 Case Study of Change Utilization ................................ ................................ ........................... 16 Allowing for Variety within Change ................................ ................................ ...................... 19 The Ultimate Simplicity of Change ................................ ................................ ........................ 22 The Solution of Functional Learning Curves ................................ ................................ ......... 22 Change is Dependent upon Time ................................ ................................ ............................ 24 2 LITERATURE REVIEW ................................ ................................ ................................ ....... 29 3D Print ing of Plastic Structural Components ................................ ................................ ........ 29 Rejecting Polymer Extrusion in a Process Developed from 3D Polymer Printing ................ 30 Subordination of Polymer Alternatives to Concrete Practices ................................ ............... 30 Cementitious Materials as Polymer centric Transition ................................ .......................... 31 3 PROBLEM STATEMENT ................................ ................................ ................................ ..... 33 The Current Situation ................................ ................................ ................................ ............. 33 Advocating for a Polymer Bench ................................ ................................ ........................... 34 Constructability and Perception of Concrete Versus Plastic ................................ .................. 38 Properties of a Corner Wall Section and Faux Wood ................................ ............................. 39 Education through a Shifted Paradigm ................................ ................................ ................... 41 Marketing Plastic Homes ................................ ................................ ................................ ........ 45 4 OBJECTIVES ................................ ................................ ................................ ......................... 51 Interrelated Hypotheses ................................ ................................ ................................ .......... 51 A Li mited Hypothesis using Contour Crafting ................................ ................................ ....... 51 The Marketing of Faux Wood ................................ ................................ ................................ 52 Concrete Versus Cementitious Material ................................ ................................ ................. 52 An Aside into Competing Life Cycle Claims ................................ ................................ ......... 52 Life Cycle of Concrete ................................ ................................ ................................ ............ 53
5 Portland Cement ................................ ................................ ................................ ..................... 54 More Accurate Assessment of Materials Costs ................................ ................................ ...... 54 5 RESEARCH METHODOLOGY ................................ ................................ ........................... 59 Concrete ................................ ................................ ................................ ................................ .. 59 Cementitious Material ................................ ................................ ................................ ............ 61 Faux Wood ................................ ................................ ................................ .............................. 62 Contour Crafting ................................ ................................ ................................ ..................... 63 6 RESULTS ................................ ................................ ................................ ............................... 65 7 LIMITATIONS AND SUGGESTED FURTHER RESEARCH ................................ ........... 72 8 CONCLUSIONS ................................ ................................ ................................ .................... 75 REFERENCES ................................ ................................ ................................ .............................. 80 BIOGRAPHICAL SKETCH ................................ ................................ ................................ ......... 83
6 LIST OF TABLES Table page 6 1 Summary of materials properties. ................................ ................................ ...................... 71
7 LIST OF FIGURES Figure page 1 1 Optimistic blog item regarding thermosets. ................................ ................................ ....... 28 3 1 Concrete stress strain graph. ................................ ................................ .............................. 48 3 2 Polymer stress strain graph. ................................ ................................ ............................... 48 3 3 ................................ .................. 49 3 4 ing bridge at the University of Florida student union. .................. 49 3 5 USCB information of proportion of private to public construction. ................................ .. 50 4 1 Flexural Strength against Relative Cost ................................ ................................ ............. 58 4 2 Back end energy costs of materials. ................................ ................................ .................. 58 6 1 Calculations for polymer gel and concrete amalgam volumes. ................................ ......... 68 6 2 Core wall unit construction. ................................ ................................ ............................... 68 6 3 Revit image created by author. ................................ ................................ .......................... 69 6 4 Expected physical properties of structural faux wood and concrete. ................................ 69 6 5 Unit cost comparison between generic concrete amalgam and a given structural polymer, ordered from Sigma Aldrich. ................................ ................................ ............. 70
8 Abstract of Thesis Presented to the Graduate School of the University of Florida in Partial Fulfillment of the Requirements for the Degree of Master of Science in Construction Management USE OF FILLED POLYMERS FOR STRUCTURAL APPLICATIONS By Wolfgang Ryor August 2018 Chair: Larry Muszynski Major: Construction Management Members of the construction industry overwhelmingly believe that concrete is the most desirable structural material. This ubiquity is based upon many factors, not least a historical predilection towards that composite. It is trusted due to millennia of reg ular use, and the ease of locating the ingredients. The material is also very tactile; workable as clay, then hard as steel. Concrete is familiar. Polymers bring up entirely different associations. They are commonly regarded as flimsy, The synthetic nature of plastics creates distrust. The perception of chemists in white coats and vats of gelatinous goo comes to mind. The material is distant from direct sensation. Far greater conceptualization must be engaged in when approaching polymer s. Previous research has mirrored these assumptions, and appeared almost apologetic when considering plastics for wider applications. This research has the goal of analysis of polymers without preconception, often this way, objectives based on true merit, or deficiency, may be discovered by researchers beyond a limited audience. Application of these methods will clarify relative v alue in the use of concrete and polymers Identification of the relationship of attitu des is a correlative of that investigation E valuation of respective loading capacities will be
9 performed in the laboratory, testing relative compressive strengths C ompilation s of properties in chart and table format will further elaborate the materials comparison Therefore, a combination of actual testing and reliance upon published and unpublished sources will be used.
10 CHAPTER 1 A FLORIDA EXPERIMENT In the wake of the development of increasingly light and effective sustainable building materials, the status of traditional modes of construction are being rethought. This is not just a private sector phenomenon. More conservative public entities, such as the Florida Department of Transportation (FDOT), are also utilizing this innovation. During concr ete building, for example, the standard has been employment of steel bars to distribute tensile forces. However, as structural plastics have increased in status, displacement of steel, and even concrete, has increased. A material formerl y thought of as unworthy of structural use, polymers continue to gain greater influence as a fundamental building component. One p olyme r, common in the private sector, which strengthens concrete and acts as an independent structural unit, is called Fibe r Reinforced Plastic (FRP). This family of P lexiglas may be used in many ways with flexible modeling potential The Florida Department of Transportation (FDOT) has taken a keen interest in this malleable material in current state construction projects. The reasons for this are various corrosion protection, acceleration of construction schedules, simplified procurement with less expense, and use of large and light components, such as plastic bridge piers. In fact, FRP and concrete share a symbiosis in bridge abutment and pier erection. A prevalent danger in this type of work, using steel rebar, is corrosion. This problem is often viewed in terms of anodic and cathodic relationships essentially a chemistry problem of managing electronegativity of adjac ent metals or materials. Corrosion also takes place when salt water, or vapor, infiltrates concrete. This will directly corrode interior steel rebar. However, if polymers were to be used effectively, there would be no need for any consideration of corrosio n. Fiber Reinforced Plastic (FRP) has very low conductivity and a neutral electromagnetic charge.
11 Using an FRP admixture would simplify concrete preparations for pouring, because no rebar work would need be included in the formwork. In the case of tube enc asement, as described below, the form is the FRP structure itself. Therefore, costly and time consuming procurement and laying of rebar would be absent. Furthermore, scheduling difficulties may be mitigated, with project acceleration as a result. Fiber R einforced Plastics may be associated with concrete in dust, fiber, extruded, and pultruded form. The material varies from polymerized products which are manufactured in Portland cement plants, such as fly ash and slag, in that they are not merely collected from furnace refuse FRP is more sophisticated in its chemical engineering. As a product of Plexiglas, it is derived from an elastomer with laminar properties. Therefore, it may be ground, or shaved, into dust or a fiber concrete mix additive. It may also be extruded and pultruded into virtually any shape. FRP is used in bridge piers as an assemblage to give the support characteristics of steel tubes can significan tly enhance the 1999 p. 500 509 ). Another structural approach is achieved through the process of pultrusion. This manufacturing process increases density exponentially. The product created is a so often used in conjunction with a stiff foam or pultruded corrugated interior. Both the tube and that of steel and concrete. Despite these promising dev elopments, there are drawbacks to wide application of these technologies in Florida. Construction using FRP techniques will leave polymer detritus, some of large size and weight, long after the life of associated composites have expired. While steel
12 reinfo rcement will corrode and degrade, as would concrete, the thermoplastic or thermoset FRP would have to be collected, or allowed to lay in situ. Collection would presuppose an infrastructural innovation of large scale recycling. Judging by current FDOT depar tment issued literature on the subject, it seems these hazardous consequences have not yet been fully appreciated in FDOT planning. Such a recycling effort could include strategies of policing sites and configuring the waste into extruder ready material f or solidification into storable units. The Plexiglas characteristics would be retained, and exploited again when the unit is shaved, crushed, extruded, or pultruded for a new task. Though initially expensive, FDOT has the capacity and regulatory muscle to implement this type of infrastructural innovation over several years. Recycling conditions could even be included in Request for Qualifications parameters in bidder responses for future state work. It is evident that Fiber Reinforced Plastics have significant potential benefits when applied to FDOT projects. These attributes include structural capabilities comparable with metal rebar and concrete, potential easing of schedule constraints, likely reduction of procurement burdens, and strong stand alo ne polymers of light weight. However, these technologies are not a panacea. It could be argued that sensitivity to environmental concerns would mandate future state responsibility to provide an infrastructure of recycling with adoption of FRP based constru least a decade. Conceptualizing the Phenomenon of Change This experience in Florida, matching the properties of polymers with concrete, indicates human beings are crea tures of habit. It is easier to understand new concepts in the context of previous experience. The Florida Department of Transportation has adopted use of a
13 conceptually flimsy material as a heavy structural component for bridge piers. But has this process been thought through? From the exploration just recounted, it would appear FDOT assumes that FRP has the same life cycle properties as concrete. This is not the case, and any use of FRP must carry the attribute of recycling on a massive scale. An entire f uture infrastructure is implied, which would include identifying and collecting a huge amount of material that must be treated for reuse. Preparations for such an endeavor are currently lacking. The central argument of this study is that the Florida examp le is typical of any proposed use of polymers in relation to concrete. It may be argued that bias toward prior understanding of polymers is the main obstacle in the wide adoption of this material for structural use. The word tion. However, any psychologist would assert this condition is necessary for the survival of our species. An ever changing kaleidoscope of images and sensations would bar formation of any model for the operation of this world, without bias. When does bias become harmful, the status quo insufficient? This thesis is concerned with that phenomenon. When applied to the topic of environmental sustainability of construction proce sses and materials, change may be viewed in two basic ways, as either continuous or revolutionary. The the model of a caesura between past and present could be asserted. This type of presentation is given by groups such as the International Council of Local Environmental Initiatives (ICLEI). A political agenda is the primary component of this option. Sustainability concerns are couched in rhetoric describing rig hts of indigenous populations and responsibilities of industry. The entire question is framed as an abrupt transformation of society, dismissive of the individual.
14 From the standpoint of this research such a perspective misses the real significance of the larger issue. The assertion here is that the sustainability conundrum is a continuation of technological developments to aid industry, which began in the early Industrial Revolution. The chronology of this process dates from the eighteenth century onwards The line of reasoning could trace ever increasing efficiencies of design and distribution, especially in the growth of a market economy in Britain. Emergence of perceptions of consumer very important to note in this progressi on. Advancing technological innovation brought correlative restructuring of labor markets. The theme would be continuity in development of more efficient and profitable strategies within the context of economic growth. Thus, two very different models of a sustainable future exist, at odds. The fate of DDT as a pesticide, and the development of digital communication represent the divergent ends of these alternatives. Employing the Means of Change Rachel Carson is remembered as one of the early titans of envi ronmental awareness. (1962) gave rise to a movement which virtually eradicated DDT. The chemical is an insect repellant that protects plants. An abhorrent practice was identified and public pressure was subsequently harnessed. The message was simple DDT was a killer that needed immediate attention. There were unintended ramifications to this line of action. The most significant of these was a massive increase in the third world de ath rate through insect borne disease. The employment of DDT in mechanized, large only attribute. In lower socioeconomic areas the potent mixture was an effective and affordable means of controlling mosquito popu lations. Those parasites would otherwise infect people with malaria. The immediate curtailing of DDT manufacture and distribution had tragic consequences. During the popular uproar, this more complex effect was overlooked.
15 Furthermore, there was a pernicio us assumption that DDT could only be understood through its Mathematicians have studied fractals for a very long time. These functional iterations, quations. Use of analog technology was standard in communications throughout the 19th and 20th centuries. During the early years of the space program a problem with wavelengths was identified. Antennae for long range radio transmission s would have to be h uge to pick up signals over vast distances. The situation was resolved by patient examination, using empirical methodology. Instead of an enormous dish shaped surface, fractal modeling concentrated that area into a tightly corrugated space, a small antenna with a capacity area of reception approaching infinity. mobilized mass support to address a troublesome issue, leading to common awareness of sustainability concerns. The Ap ollo missions went a long way to wards usher ing in the digital age. Again, there are two types of approaches to change, emotional and empirical. The former is immediately gratifying, but often based on slender analysis. The latter makes use of rational scie ntific methods. This choice is less exciting and more time consuming, but it lends itself to progressive examination. That crucial appeal provides the necessary prerequisites to truly ponder altering patterns of behavior. The current research assert s that sustainability solutions will be found over the course of the next 100 years. That timeframe will become very important as this analysis progresses, because a fundamental change in cultural perception and construction modalities must occur. Therefore, the approach to sustainable building will be made in a bifurcated manner discussing a relatively straightforward proposition, along with the wider ramifications of its acceptance. The
16 proposal is that polymers should be utilized to a greater degree as a stru ctural component, versus concrete. A spotlight will be cast upon this hypothesis, which will also treat the societal structure that supports concrete as the traditional choice. Case Study of Change Utilization The delivery mechanism employed for this co mparison between plastics and concrete, will be capable of dispensing both materials. This method of modeling identical processes, using each alternative, will greatly aid in presentation of clear conclusions. Application of life cycle assessment (LCA) wou ld possibly benefit this analysis. But, as the story at the beginning of the dissertation indicates, logical discontinuities and historical bias es greatly influence evaluation of life cycle costs. An example is that of the recycling dilemma of FDOT. So that aspect of the discussion will be omitted. Contour Crafting had a promising potential as the result of a long term study by an academic institution. The automated mechanism central to the project was highly technical. It made use of sophisticated softw are capabilities, 3D printing innovation s and contiguous pattern building. The use of concrete and ceramics as primary structural materials perpetuated traditional expectations. The system operated through the use of Building Information Modeling (BIM). T he computer program created an exact virtual fabrication of the building. The structure was visualized complete with material attributes, details regarding placement of every component, and the ability to monitor actual progress. This was accomplished wit h a gantry mounted with extruders, nozzles, and electronics, which behaved just as a stylus would with a miniature printer. The gantry travelled a path over parametrically pre determined 3D shapes on a grid. According to the breakout literature, the mechan ism was designed to deposit five inch layers every hour, including piping, wiring and forms. Materials were extruded in a paste, with concrete amalgam as the core, which cured as the machine followed the template. This layer by layer
17 strata creation was ca pable, for example, of completing a 10 foot high dwelling in 24 hours. Integration of the completed product with its surroundings was also an important goal. The new delivery method was called Contour Crafting. Although it was possible to use the technolo gy to construct individual show pieces, that was not feasible unless the owner had considerable assets to invest The complexity of the machinery involved lent itself to mass utilization. It was envisioned that the system would operate on a large plat of l and. Development of this process had been very dependent upon research. It followed that corporate support, as opposed to a specifically entrepreneurial enterprise, was the paradigm. Funding came from a concrete conglomerate. A driving force behind the met and theoretical. Theory was exemplified, for example, by literature describing aspirations for the invention. There were many suggested applications some by their very nature rather utopian. A particularly revealing s cenario stressed rediscovery of the ancient method of layered construction within the technology. This certainly was the Contour Crafting manner of creation layer by layer, via gantry. However, it was envisioned that locally abundant natural materials cou ld be fed into the system to produce culturally sensitive structures. This type of niche application was revealing by its appeal to activist opinion the first option as described above It alluded to socio economic goals associated with ICLE I, the politic al entity that supports full incorporation of regional economic and cultural conditions as preconditions for sustainable construction. Absence of accomplishment in local ized construction revealed the technology had not lived up to those ideals. The real a im was to align with a powerful ally to tout this theoretical vision, very consistent with academic standards. To continue with the assertion of local materials use it is worth reiterating that the delivery method was most realistically designed for urban
18 construction in developing nations. The reasons for failure of this vision were several. For example, any local material used would need to be mixed into a workable, chemically composite paste. It then would have to be distributed to multiple gantries on large projects. An enormous supply would constantly have to be made available. This was hardly something that could be done properly without sophisticated procurement and expensive bureau cracy capabilities hard to find in the Third World A consequence wo scope, with lab facilities brought on site. Even if movement of the apparatus was found to be possible, a rural environment would almost certainly lack the ready support chain upon s complicated system is depend ent Thus, the discussion turns to a Cornell analysis (Weinstein and Nawara 2015). The study addressed respective probabilities of the process becoming an acceptable building mode in developing nations. Among the conclusions it was found that developing nations were not in a financial position to choose building these large public projects. The point is that Contour Crafting literature portrayed a comprehensive delivery method. It presupposed many assumptions that have borne l ittle correlation to reality. This fact has also impacted flexibility in considering anything beyond concrete and related composites, local or otherwise The Cornell article ( Weinstein and Nawara 2015) includes an estimation of third world government funding by each nation that employs Contour Crafting. The funding will come from each nation, The original vision for Contour Crafting consisted of a variety of applications, ranging from inexpensive mass housing to ex traterrestrial colonies This has yet to materialize. The product has yet to be proven in the marketplace. Polymers could readily be used B ut they are relegated to subordinate components usually fibers or pellets diffused within concrete structural
19 forms The technology has suffered a distinctive lack of definition in real world situations. Its by default, eschewing a wider market founded on aggressive identification of entrepr eneurial possibilities This strategy presupposed certain truisms about materials especially those which were considered as natural ly deposited The ICLEI local model assumed an indigenous composite supply would be utilized by the technology. There appea red to be little thought about ultimate deposition of extruded elements The use of plastics was only defined in association with modalities defined by potential r ecycling dilemma. So, ironically, the biodegradability issue could be exacerbated by this subordination of polymers to concrete leaving a widely scattered detritus of mingled cement, polymerized dust and fiber across the landscape. Allowing for Variety w ithin Change Still, the concrete amalgam dispensed through Contour Crafting is generally viewed as eco friendly; plastics are not. That is just the way it is. T hermoplastics are recyclable, but less desirable because they are not a natural alternative. Op inion about thermosets is decisively negative. They are often considered the worst option neither a natural n or a biodegradable substance. All t his exemplifies a lack of rational investigation reasoning that denigrates p olymer s within a framework of conceptualizing change as an immediate imperative These patterns of thought and behavior are specific examples. However, they represent ingrained attitudes which constitute repetitive myopic narratives of current environmental doctr ine. The message is that everything must be radically realigned It is little wonder, when discussing sustainability, that near panic is the next resort change became a hot button issue, the intensity of opinion has b ecome progressively galvanized.
20 All too often, those engaged in this conversation respond to emotional appeal. An ever present danger is that discussion will turn to simple propaganda, that pesticides taint apples which then harm children. This thesis will attempt to provide an optimistic alternative to such negative sentiments A skeptical viewpoint will not be adopted. The intention is to present a thoughtful, creative illustration of the future. While attention will be centered upon an admittedly limited subject greater reliance upon polymers in the fabrication of structural units, the findings will be extrapolated into a constellation of further possibilities for research. The dual intent will be to define a narrow topic, while alluding to the bi g picture. It will be the contention of this dissertation that a cultural learning curve must precede any real evaluation of effective sustainability initiatives Solutions and processes wil l be devel oped when varying practices are utilized by millions of people, over an extended period. This dispersed unless restrained by political or bureaucratic measures. The drivers for those type of restrictions would likely be the determination by those in influential pos itions to apply doctrine. The development of doctrinaire attitudes has been caused by assumptions that the situation to be corrected is well defined at this point. On the contrary, long term effects are difficult to foresee. So, a very large factor affecti ng the conversation is the assumption that sufficient information now exists to make wholesale conclusions and provide appropriate responses. This is contradicted by the longevity of the climate change argument. The problem has not existed for long in the general consciousness. It is far beyond the scope of this research to study the cause. This is only noted to illustrate that such paucity of experience has created, in some minds, an apparent failure of the mass of people to appreciate its gravity. An unfo rtunate by product has been impatience and somewhat shrill political and social coercion polarizing reception of the
21 message within public discourse A related difficulty arises when individual choices are framed as either enlightened, or regressive. Thi s temptation to criticize established modes of building behavi or can serve to separate, rather than to unify opinion. An example may be helpful at this juncture. Suppose a decision were to be made regarding sustainable properties of a primary struc tural m aterial. The parameters of argument are to be influenced by the mindset described in the previous paragraph. For example, t ake the construction of a re sidential building A home is a statement of personality If an owner were a trailblazer, they might opt for a fiber reinforced polymer (FRP) dwelling. A different owner might make a similar statement about their proposed home by selecting construction with a concrete amalgam, applied through an automated process. The former owner would place far greater emphasis on use of a non traditional structural material; the latter would value a non traditional building process. Dependin g on a given attitude, either of these choices could appear progressive or regressive. The po lymer home, due to biodegr adability concerns could be disparaged. Likewise, use of an automated process to build a concrete dwelling could likewise be criticized for the extensive use of a material whose manufacture contributes to approximately 5% of greenhouse gases. The conundru m rests upon whose decision is deemed correct a relatively small group of experts or each person impacted. T he presumption here is that there are myriad paths to achieve sustainability goals Suggestions that stick will do so because they are empirically convincing eventually overcoming bias. The dangers in preferential selection by experts is very tangible with greenwashing. In this way, emotional reactions to products and practices have been tamed by pseudo science in support of their environmental bene fits though the case could be too complicated to render carte blanche approval. This situation is so prevalent that the certification
22 agency Leadership in Energy and Environmental Design ( LEED ) publishes very specific parameters about the subject. For e which is targeted products and practices (Poplar 2014) The Ultimate Simplicity of Change Contrary to the argument outl ined above, bias is not just historically based and societal. When a researcher studies various processes and materials, the possibility of individual bias is ever present. Just because something is interesting, emotive, or novel, does not mean it has inhe rent value. An internet search returning something at the top of the list does not give that information any more weight or accuracy. In response to such concerns, this paper will use methods elaborating specific conditions indicative of the whole analogo us conceptualization. One such will be comparison and contr ast in the evaluation of factors effecting cost of a small generic home, using both polymer and concrete as a central structural material. M ethod ologically, this means application of comparable subjects apples to apples. Simplicity will eliminate distractions, as well as nuances of highly complex and conjectural issues. In lieu of entanglement, the focus will be maintained up o n limited subjects, with a tactile attraction. This is not a manifesto detailing remedies for complex and intricate problems. Underlying this discussion is a simple plea for better understanding of necessary transitions, defining elements of that huge process using continuities of past development. The Solution o f Functional Learning Curves It follows that respect will be given to the status quo, in t hat it is the origin of general perceptions regarding present affairs That point must be clearly stated, due to difficult ies which arise when engaging in abstract an alysis A common mistake is discounting those whose liveli hood depends upon current building modes Those who have invested in such modes should
23 be given due consideration. Everyone from the miner extracting ore, to the teamster transporting it, and the pa ver who places it, receives more than just a paycheck. The author o f a ground breaking book about the psychology of project management Management defined internal motivation and team dynamics (Wong 2007). The author recounted h istorical research enumerating rewards for participating in employment (McClelland, et al 1953 ). According to Wong, quoting McClelland, a achievement attain realistic but challenging goals and gain achievement in the job ; (2) power lead and have their ideas prevail; and (3) affiliation (Wong 2007, p. 23). Anyone who has been un employed can attest to psychological dislocation and loss of self esteem experienced by the absence of expr ession through labor. Work is identity even if those doing it cannot elaborate that concept The manner in which an employee deals with this at times subconscious empowerment defines their identity. Intangible rewards therefore flow from labor M any go unrecognized until the job is altered possibly disappear ing altogether. Labor practices represent a continuum. Employees understand the progression of modalities And, by repetition, a style of performing new tasks becomes unique to every individual b ut also becomes streamlined. This learning curve, the way someone co mpletes activities, is a crucial concept. It may be described as a cognitive bridge from current to envisioned practices. If a construction curve that person would probably visualize a fundamental sche duling technique of construction planning. Everyone in the profession acknowledges its value That means there is commonality of definition that may be used to persuade the reticent.
24 Change is Dependent upon Time Questions opposing human versus environmental benefits are volleyed back and forth Arguing those questions would be an invitation to unproductive responses to change It would presume an adversarial relationship exists; one must suffe r at the expense of the other. The idea that human beings have become alienated from their surroundings by economic and tech nological development would further complicate things. This somewhat vague notion has a long lineage beginning, at least, with the advent of Luddite philosophy. A hazy, romantic version was expressed very well by a Victorian era academic writing about the decline of compensating advantages. It wa s neither ugly nor unnatural. It was lived in the country, and whatever man himself added to nature did not detract from the (Treveleyan 1953, p. 219) It is argued here that following this type of reasoning presents endless pitfalls. On e would only need to reflect upon possible conflicts arising from such beliefs the most view. Is any sort of building an affront to natur e? Discussion of such a slippery topic could very ea sily degrade into a stalemate. Again, intricate and subjective ponderings are well beyond the scope of this research. The assumption made in this analysis is that a tectonic shift must occur, possibly signaling a change in epoch. This progression will most probably be measured in decades, or centuries. A correlative assumption that of environmental practices being subsumed by centuries long development of productivity, answers the counterargument that big decisions must be made immediately. Imminent danger remains unproven; there is time A model incorporating that constant takes shrill alarmism out of the equation. Such a template of environmental conditions is not without its detractors. For the purposes of this study however, it is the most useful means
25 of concentrating on well targeted analysis. In other words, the goal is consensus about sustainable strategies, that will be workable as soon as possible. So, l ack of success in transmission of the message can therefore be imp roved by respecting the role of time. S tud ies in trans ition of technology chart beta curve s adoption increases in pace and then re aches the critical apex. The curve then descends rapidly as a shrinking number of recalcitrant non adopters succumb to inevitable change. It is a gen erally accepted fact that automation and new materials can be of great benefit in achieving the goal of sustainable construction. The capabilities of these applications could improve the built environment in startling ways. Given time, and the proper techn ological means, hardly an aspiration would escape realization or problem, a solution. With these possibilities in mind, a specific question could be asked about whether concrete should continue in its traditional role as the dominant structural component. Furthermore, considering the implications of automation, would there be a better alt ernative going forward? Th e research here will explore whether polymers can become that material. The linking of computer software with new use of materials has opened ma ny theoretical advances in the field of lean engineering Such innovation could create patterns of sourcing, supply, and project management radically different from the current paradigm. This change could greatly influence materials processing, component m anufacture and traditional labor and sequencing of distribution. Anything could be delivered anywhere in the world at competitive cost in any quantity. This coupl ing of information technology and economies of scale could greatly ease the expense and time lag of materials delivery. If there were a d istribution system that could integrate all these features, the effect w ould be transformational. It
26 will be asserted that eventual societal commitment could create enormous recycling networks These infrastructure systems would be further enabled through internet supply chains. Economies of scale only wait for a spark to conflagrate. Mass production and distribution shou ld be expected to beget efficiencies. Even without large scale support, many companies already have made significant strides in re sourcing the most feared polymer class. A company, called Northstar Recycling, is one example of this latent capacity for inn ovation. They have specialized in the repurposing of thermoset plastics a major environmental concern. It is well beyond the limitations of this discussion to argue for specific policies to achieve such a situation. However, as stated above, an assumption of technological optimism exists Given time, people will come up with solutions. As will be seen, the case for optimism is strong. In his 2012 TED talk a n architect named Michael Hansmeyer has some fascinating ideas about means to extrude polymers. These concepts, if allied with Contour Crafting, could generate mass producible polymer buildings made of super lightweight structural components. This could be done by allying computer software mode ling with biomimicry principals. Modeling based on biological structural integrity, on a very small scale, has already been accomplished. Through exploration of polymer combinations, the technique could be perfected over the next several years. Imagine co Pursuant to the discussion that use of local materials would be complex, polymer mixing would o produce the exact recipe for any project conditions. There are firms such as Sigma Aldrich, Americhem, and Curbell, who specialize in doing this very thing But, they lack sufficient infrastructure, so costs remain high. Still, with proper support any o f these companies could take
27 customer specifications an d complete the order online (assuming adequate lead time) for virtually any proportion of ingredients and mixing techniques. The chemical manufacturer would then test, create, package and send the fini shed product wherever needed, in whatever bulk. Polymer pellets or sand could easily be emptied into the extrusion hopper. Due to the tunability of polymers, a rriving at the exact chemical lattice configuration and then delivering it, extruder ready, would be relatively unchallenging. Imagine the future! Automated delivery systems could create fully recyclable structures on a mass scale. These would be like jigsaw puzzle pieces in the box. If they are laid out and matched, potential benefits would include e radication of slums, provision s for vast new employment opportunities, and an effective market based strategy in response to climate challenges. All that is missing is investment in flexibility. It must be iterated that the intention of this research was not to provide half measure solutions. While it is understood that necessary transitions must have intermediate forms, those forms are not the terminus envisioned. Likewise, the notion that polymers must be subjected to apologetics is rejected. There are n o excuses needed when arguing for superior material properties and function. The thesis is that plastics should be considered on an equal footing with concrete, and if time is allowed, that piece of the big picture will fall into place.
28 Figure 1 1. Optimistic blog item regarding thermosets. http://www.northstarrecycling.com/new opportunities to recycle thermoset plastics/
29 CHAPTER 2 LITERATURE REVIEW 3D Printing of Plastic Structural Components processes (Hansmey er 2012). The architect elaborated his point while discussing column design in front of a TED audience had the potential to span the micro through the macro sphere. He continued: they [the column components] have information at very many scales. We can begin to zoom into them. The closer one gets, the more new features one discovers. Some formations are almost at the threshold o f human visibility. 2012). This algorithmic approach made use of fractal iterations involving repetitive halving. A theme of s that software could do this and provide consistent structural However, the architect acknowledged his process was too cumbersome and limited in scope to be immediately applicable. He was almost certainly using ac rylonitrile butadiene styrene (ABS), polylactic acid (PLA), or similar polymers in common use, to perform this modeling. The brittle quality of those media stopped the dreamer in his tracks. fact, soluble. Progress has been made in 3D printing, reducing inflexibility of forms particularly on a small scale. In their research of polylactic acid/ polyolefin elastomer (POE) mixtures, scientists found the presence of POE in PLA foams has a g reat influence on their mechanical properties and
30 t oughness (Forghani, Azizi, Karabi, and Ghasemi 2016). The study centered upon capabilities of foam insulation, but the results were quite applicable to computer modeling processes that employ ident ical materials properties. That study illustrated characteristics of existing polymers, used in new modalities leading to discovery of workable structural combinations. Rejecting Polymer Extrusion in a Process Developed from 3D Polymer Printing The solution to any given problem will not be contained within just one monomer chain. Whether thermoplastic or thermoset, interoperability is the very principal inherent in the 3D printing concept. That concept has been a parent to Contour Crafting (CC): a gantry system carrying extrusion nozzle(s) mov[ing] on two parallel tracks installed at the construction site. Trowels smooth the surface of the layers as the concrete is extruded. The cement does not require forms each layer extruded can keep it s form as each successive layer is added (Weinstein and Nawara 2015). Contour Crafting is not new. The effective filing date for the U.S. patent was October 26, 2006. This sustainable construction method could be most useful in developing countries in nee d of reliable, inexpensive, and safe mass housing. The economic feasibility of that research virtually guarantee d assembly line building techniques. The Cornell study authored by Weinstein and Nawara, analyzed the respective probabilities of Contour Crafti ng becoming a viable building mode in developing nations within these parameters. Subordination of Polymer Alternatives to Concrete Practices That technology is a conduit to future applications envisioned in this review. B uilding information modeling (BIM ) software was used to direct construction of CC projects M aterials selection c ould be changed in a heartbeat. This presented a natural op portunity for deployment of polymers with their tunable properties and flexible use A range of plastics we re already being utilized in this manner, as noted again by the Cornell study. For example, reinforcement of the extruded concrete amalgam is often provided by fibers or pellets. These reinforcing elements
31 need only be loaded into the gantry nozzle to be m ixed with the amalgam as it is layered. That is a contributing factor (along with the narrow width of concrete layers) to the self supporting quality of the fast curing amalgam. A pivotal issue concerns concrete amalgam T here have been no concerted effor ts in the past decade to explore new materials Only concrete has been deemed acceptable. Conversely, would most certainly entail using a chain polymer like iteration, thus eliminating concrete as an option. The material is strong and pos but would be too brittle to perform such exquisite modeling. A likely motive for the decision to use only concrete wa s explained by a USC College of Engineering press release touting CC, i nstead of plastic, Contour Cra concrete formulation provided by USG, the multi national construction materials company that has been contributing to Khoshnevis' research for some years as a member of an industry coaliti on backing the initiative (Viterbi 2008). A major factor for the persistence of concrete use is its mass application, which could expect to provide a profitable market for expanding CC projects. Cementitious Materials as Polymer centric Transition Support given by the United States Gypsum Corporation, ( USG ) has been a constant (Viterbi 2008). It c ould be argued that both these conglomerates h ad a vested interest in keeping concrete as a central ingredient of the Contour Crafting process There wa s a study examining the use of silicon dioxide based mixtures which could give an opening to employment of organically based, polymer like compounds. Th is development would potentially be consistent Strength and water permeability of the specimens have been improved by adding SiO 2 nanoparticles in the
32 It al so must be noted that there we re several competitors using CC technology, possibly beyond control of patent restrictions. This may lead to the supposition that research and development of extrusion plastics (or even organic equivalents) to supplant (or mod ify) concrete amalgam, may come from abroad. Still the question persists whether plastics could subsume concrete in Contour Crafting. Another agent which had success in prevent ing concrete shearing was Fiber Reinforced Plastics (FRP) which used a filler of polymerized waste produced by the manufacturer of Portland Cement This family of Plexiglas has also provid ed in dust form, an integral component of tensile resistance in concrete. Yamada and Mihashi ( 1995) discussed these properties during a co of FRP powder is similar to silica sand. These [findings] suggest FRP powder use as a substitute of silica sand [in] an extrudable (sic) compo relationship, but the change from mere additive to integral component is intriguing. The material properties touted in that research describe a polymer. If there were such a substitution, an important feature of C combines an extrusion process for forming the object surfaces and a filling process (pouring or injection) to build the object core (Khoshnevis 2004). The core need not necessarily be enclosed. The produ ct extruded could be in molten form. Less troweling would be possible because it would be stand alone material. Another intriguing idea that expresses the scope of change inherent with a shift of core processes which previously revolved around concrete ama lgam.
33 C HAPTER 3 PROBLEM STATEMENT The Current Situation Much discussion has been expended, thus far, upon possibilities for new polymer applications. That vision could be quite a long time in the making. The predominance of concrete in the building industry is questioned only on occasion. The main effort toward development of sustainable building materials is going into design of increasingly efficient cement based products, using polymerized ingredients. Government transportation agencies now often consider those types of mixtures satisfactory substitutions for concrete. It has already been shown how FDOT planned to use structural polymers for bridge piers in place of metal and concrete packages. This paper has argued this ultimately an unsustainable practice, not least, because recycling strategies are not in c oncert. For example, polymerization of dust ingredients for cementitious materials, for recycle, is dependent upon furnaces manufacturing Portland cement. So, there is no clamor for change to a totally different material, a true transformation. The tipping of the balance so evident in the climate change debate has not been replicated regarding concrete dependency of the construction field. The polymer debate awaits the advent of champions to argue its cause. A mass advocacy is needed, a critical number of p roponents to make the case. The following apologetic is very specific in its delineation between objective and subjective factors of material properties. This type of argument is effective because it invites comparison, convincing and audience with contras ts using topical subjects. A balance is found by using science to highlight misconceptions about points familiar to the listener. People must be convinced using understandable persuasion. The average person tends to believe they grasp the substance of the mundane, things encountered every day. This arrangement of objective
34 evidence, revealing the mundane, exposes unconscious perceptions that are suspect. In this manner, transformation of thought can be achieved. Advocating for a Polymer Bench Examination o f common objects could, therefore, provide analogies to more complex matters. The following discussion could be truncated at any point, or given detailed elaboration for any audience so inclined. It could begin with a simple proposition. For example, a lis tener would be asked to i magine a generic structure say, a bench in the front yard of their home. It will be built with an elongated seat. The superstructure will be supported at e ither end, possibly with separate pieces to aid in portability. This bench would also represent a loaded beam. The case to be made is that of polymer use as a structural component. Therefore, the task would be to select the best construction material. Excluding natural polymers (wood) there would be four common alternatives from which to choose: metals, ceramics, composites, and non organic polymers. There would be many factors affecting each choice the object should appear reasonably comfortable and stable, or at least give the impression of functional ity to casual inspection. In other words, it should possess constructability satisfaction of the end subjective vision of a bench. It is axiomatic that any selection would depend upon individual taste and priorities. But, appearance will not guarantee constructability Th is bench must possess objective properties which insure durability and it must function properly This dichotomy between actual material content and performance contrasted against lay at the heart of this ex ample The goal will be to expose the complexities of apparently straightforward decisions. T herefore would be helpful to take each choice and examine both its physical properties and psychological effec t T he most obvious concern for most people would in volve cost. A metal design of a strong, supple, and lightweight aluminum product would
35 certainly present an attractive and functional option It would be easily movable and look durable. Aluminum could also be twisted and crafted in interesting ways. Speak ing of malleability, copper would be better, due to features like the classic green patina it would acquire through weathering. Both these options would be expensive. A customer would most probably look to obtain equivalent performance with less cost A ch eaper metal would be more than adequate such as that of s teel, or iron. With approprate coating, each could patina finish, or the shine of aluminium When employing lower cost metals for seating, there would be at least two major concerns conductivity and weight. Discussion of bench selection for an outside restaurant, or park, would include these important properties C ustomer seating would encourage turn over. A material that is a conductor of heat and cold would be desirable. A heavy, formidable looking bench would also discourage vandalism in a public place. I f the proposed outdoor furniture w ere to be in placed at a residence exuding a welcoming environment, the parameters would change drastically. Conductivity w ould be a drawback; s weating or chilly visitors, perched at the edge of their seats, would not do at all. And, a totally immobile bench which could not be moved under a tree, or next to a backyard pool, would further exclude this choice. The argument is working its way toward s a polymer structure. A ceramic bench would mitigate, though not remove, the conductivity issue W eight would be lessened. The shape could be sculpted to fit any taste. These properties would generally meet the evolving criteria. Because they are essentially kiln made, ceramics are by their nature brittle. A bench composed of the material would be prone to cracking over a large surface, under its own weight. It would need to be constructed in sections. A solution for this would involve expensive op polymerized sand resulting in greater
36 tensile resistance This would most probably eliminate a ceramic choice, while suggesting plastics The option of polymerization would bring the choice of a composite material to the fore The traditional composite used in construction is concrete. This cement based material has very high resistance to compressive forces. It also is strikingly formidable by inspection, due to expectations fostered by historical use from time im memorial. Concrete would possess similar conductiv e properties to ceramics due to the insulator absorbency of Portland cement and sand ingredi ents. The weight of concrete would always be a problem because even when the composite can support itself, it is restricted in area without reinforcement. If the material covers too much area it will crack from the effect of gravity. Even with reinforcement, cracking often occurs at the edges bling infrastructure could be mentioned at this point, attributable to this condition Plastic fibers introduced into the mix would greatly insure stability. At this stage in the discussion, the listener would be brought full circle. I f using polymers were an option, it would make sense to go all the way by selecting a completely plastic bench Extent of the materials suitable properties for the job could be elaborated. Polymers are composed of molecular chains. Although there are exceptions, the propagatio n of such latticework would distinguish them from the other materials through tunability of the molecular composition The listener could learn more about tunability at this juncture. That property would enable chemical adjustment to imbue a plastic struct ure with virtually any desired qualities. The nature of this lattice creation could induce permanence, creat ing a product that would not necessarily promote bio degradability. But, that situation need not become axiomatic because modulation of crystalline formation is also tunable. Other selling points of plastics include great flexibility and strength. The material
37 can easily be made in colors; it would take little effort to c hemically add metals or halogens to give color attributes. This would just entail direct mixture: manganese could render pink; sulfur and chlorine, yellow; bromine, red; gold and copper, gold and copper. The elements would merely link to whatever chain is present in the vat solution. When d iscussing these features as a priority, it would be important not to confuse the structural material with another plastic elastomers. This type of plastic produces rubber and glass. These elastomers lack the stiffness ne cessary for a structural unit. It could be stressed to the audience that physical strength of polymers lies in their density, most often achieved by cooling of the molten material. Plastics are also noteworthy among the group of proposed materials because they are amenable to melting and recasting into infinite and complex shapes. They can be formed through an extrusion process to exhibit a wide variety of properties. One such is high density to behave as a structural unit a loaded beam. A typical extruder operates somewhat like a conveyer belt, heating plastics from various states when put into a hopper. An interior auger distributes the gel with uniformity. H eated to a molten state, the plastic could be either directly deposited into a form or applied th rough a trowel, to create the desired object or continuous shape This is not the only type of extrusion. Pressurization c ould also act as catalyst to molecular chain propagation. In this procedure, a polymer gel would be extruded to dry when exposed to o xygen. The process has been incorporated into mainstream construction practices. techniques utilized include spraying of foam insulation into wall cores, or into a dome like configuration as support for a subgrade shotcrete roof. The rate of drying depend ent upon ambient temperature, would determine the exact properties of the plastic. This would most likely
38 fail to produce a true load bearing element. Issues surrounding control of environmental variables would make the effort prohibitive. Constructability and Perception of Concrete Versus Plastic At this point in the discussion, it would be prudent to remind the listener that t he basic intent of the entire supposition is to demonstrate the capacity of structural plastics. In this situation that would invo lve fabrication of a uniform component with concrete or ceramics level resistance, adequate to handle compressive forces. Tensile r einforcement would be unnecessary because ould be tuned through monomer and repeating molecular unit propaga tion In Along this line of reasoning, the audience would be invited to conclude that, absent subjective factors p lastic c ould very well be come the ideal choice. It could also be pondered that a favorable view of this selection would depend upon percepti on s of constructability, regardless of objective evidence This concern could become paramount Subjective standards of functionality, stability and attractiveness may be come determinate. The goal would be to highlight to the listener that the a lternatives of a concrete or polymer bench could be evaluated, independent of constructability prejudice in an empirical manner It would probably become clear that the main barrier to polymer use would involve the general subjective preference for concrete. Attent ion could then shift to further objective evidence in support of a polymer, why an objective decision would be so important for the sake of structural safety. The proponent of the case for a plastic bench could thus posit a scenario altering the load, addi ng an equal length backing at a 45 angle This would favor selection of concrete if only conductivity were to be considered. A plastic would be largely heat neutral. Concrete w ould retain warmth and cold in moderate amounts. People would enjoy a cool surf ace shaded by the seat back in hot weather, or in the cold from warmth generated by sun. But these features would be negated by structural
39 factors. Even with careful reinforcement to manage tensile load, the weight of this composite could very well generat e diagonal cracks along orthogonal surfaces. The concrete would almost certainly fail. A counterargument could discuss the solution found in the amalgam arrangement discussed regarding ceramics. Polymer fibers could be introduced to strengthen the concrete as it cure d That, in fact, is representative of current practice. The material is regularly cast in molded shape, only supportable with rebar or introduction of polymerized additives. The stability of the concrete is at times tenuous in these situations. But, constructability perceptions dictate the subservience of polymers. The audience could then be reminded of the FDOT example of bridge piers with plastic profile sections supporting a concrete column. Properties of a Corner Wall Section and Faux Wood S peaking of columnar shapes, t here would be less force ( tensile or compressive ) for which to account if the bench were analyzed as a loaded beam. However, if the bench were to be tipped up endwise and secured at the base, each material may be more definitiv ely examined as a corner column compressed from above. Contradictions in this matter of choice could then be illustrated in greater relief. A reasonable loading in the column scenario could be visualized as a wall corner supporting the side of a building. If the area of each side (seat and back) were extended, say threefold laterally, the altered picture would be complete. A fundamental flaw would become evident E ven with reinforcement, concrete at a 45 angle would gain exponential tensile strain Under th at force, each side of the concrete wall would compress and acquire an upward thrust, counter ing internal displacement. Common damage to concrete resulting from this type of orientation would be cracking along a 45 plane, as internal strain would add shea r stress from support connections A nother danger of this configuration if steel rebar were used, c ould be crevice corrosion. The porous nature of concrete could allow metal reinforcement to
40 to the interior The flexible quality of a polymer column would tend to disperse the weight, though with some sacrifice of stiffness and possible deflection. These drawbacks need not become threatening, assuming the material would ha ve been heat treated to retain a high crystallinity. If placed in appropriate conditions, thermoplastic constructability effects c ould be manage d. Departi ng from the discussion between advocate and audience, the supposition has been incongruities of perception. subjective definition of constructability. For instance, c oncrete is often shaped to mimic stonework. Plastics could also be used as an underlay to a veneer giving the same impression; take faux wood molded into plank form. Such an arrangement can be found in the deck of a footbridge at the University of Florida student union It is ve ry convincing and is only given away by the small Phillips screws securing each plank. W alking on it gives the sense of moment without bending a sturdy wood floor. Furthermore, the sound of each foot tread is almost absent. So, really, the only sensations are those based on preconceptions of what a good bridge ought to be. It is left to the individual imagination. When context is considered, the importance of atmosphere is very noticeable. This emphasizes the contextual nature in any process of changing a ttitudes. Reitz Union has been recently renovated and this arrangement is indicative of a well thought out effect. Any student who regularly uses the building (it is almost impossible to avoid) must follow a learning curve to navigate the facility. That s ame student is confronted by subtle and direct choices These choices, such as the bridge, are intended to educate that person regarding qualities of a sustainable building. Each student is habituated to certain practices when encountering the central featu re of this university.
41 Much the same point can be made about the use of polymer A ttitude s may change when it may be imaged with much the same building capabilities as concret e. There need only be the willingness to engage in the exercise From this perspective, decorative s ingle planks of the faux wood could be central to an automated delivery construction method or traditional uses. So, quite mundane paths are possible to acclimatize the mass consciousness to new possibilities. Such a transition could involve pondering whether up ended polymer planks could be combined as structural columns in traditional homes. This would challenge convention because decor ative faux wood is often applied to concrete and steel columns to give the impression of a wood beam. T he planks need not be subjected to a mold for effect disguised as accessories. They could be fed into an extruder on the Contour Crafting gantry. The mo lten product could then be shaped by trowel while layered by the nozzle to cool as the gantry moved along faux planks in different state, stacked upon one another. In this orientation, they would need less brittleness (due to dimensional support in the vertical) and could be engineered with ease by chemists as thermoplastics, with less density. An advantage c ould be ready recycling at compl etion of their functional life. Th e learning curve in this entire process would encourage variegated and expanding pathways towards recycling, by generalized application and repetition. Such a process would re quire hypo thesis of this paper is the crucial factor of single decisions, summed in critical mass to create technological and productive change. Education through a Shifted Paradigm Within this paradigm, the audience considering bench material could better grasp po ssibilities of polymer use in applications far exceeding lawn furniture. T he person w ould through familiarity, contemplate much more adventurous applications. To back up this possibility, a stress strain graph comparing concrete and polymer structural qua lities could be
42 judged with a more critical eye The two graphs below illustrate effects of maximum levels of force on an experimental concrete beam (left), and a that of a thermoplastic (right). The bench is essentially a loaded beam. The left side depict s the response to an applied force as an initial linear relationship between stress and strain then with a sustained parabolic curve. This represents initial loading and then sustained compressi ve stress on the top of the beam, with a correlated elongat ion caused by tension stress on the bottom. The apex of acceptable compressive force is just before the curve tangent becomes negative. From then on, the beam experiences a reduction of compressive force capability and tensile forces become determinant. As the curve grows increasingly negative, the composite can be seen to crack (if pinned in the diagonal) and to crumble. There is an instance on the curve where the beam will catastrophically fail. It will not snap (as would a thermoset brittle plastic) but deteriorate as the parabolic line tends toward the asymptotic limit of zero. The failure will be demonstrated by concrete dissolving under the weight. The composite breaks apart because there is not enough consistent allowance for the growing strain, or i nternal displacement, caused by tensile elongation. The remedy for this decay would be steel or polymer reinforcement. The plastic has a built in response to such elongation. When looking at the righthand graph there are three lines. The plastics shown hav e very little common molecular structure. The one labelled as brittle is thermoset, or hard T he middle is a thermoplastic; the bottom is a polymer demonstrating almost elastomer flexibility. This discussion is focused on the middle curve. As with the conc rete, the initial loading produces a linear relationship between stress and strain. What happens afterward indicates the true misconception regarding respective strengths. The bump just beyond the end of the line shows the proportional limit of the plastic In other words, this is the instance where initial loading ends and tensile forces become significant.
43 It is important that the curve does not bend downward, but beyond the bump, exhibits a convexity. Remembering the concavity of the other graph, a key property of a thermoplastic is revealed It carries within its own form great tensile resistance. The graph indicates this by the attenuated curve. The material can take a great deal of internal displacement. On the molecular level, the polymer has created crystals with long tails. To visualize this activity, imagine opening a package containing a plastic rain poncho. It is folded in long horizonal alternating layers in an accordion like fashion; a fold on this side, a fold on the opposite. It is done in th is manner to allow air to escape, avoiding en trap ment that would increase package bulk. This same concept is observed at work in the crystal tight alternating folds which decrease density while providing essential strength C rystals initially attract hig h energy until the lattice regains equilibrium. The resulting molecular texture discourages chain layers from sliding. This allows flexibility, while maintaining an acceptable stiffness. Of course, there is an instance on the graph when the polymer will sn ap But the load resistance factor c ould be determined well before that eventuality would occur. Another way to view the situation would be to reflect if concrete seats were to have concrete backs. The structural integrity of such an object would be unsound, without a great deal of accommodation. If the back were at an obtuse angle it would need a prohibitive amount of reinforcement. And, if it were at a right angle, the distinct possibility of the o ccurrence of diagonal fissures (a danger at any orientation) would make this option equally prohibitive. The solution is very revealing, often to satis fy a prejudice toward stability with the more amenable plastic using subterfuge. An example would entail extrusion of a plastic bench, with a marble patterned overcoat of paint added superficially.
44 The need to develop sustainable building materials and techniques has accentuated the deleterious effect of current presumptions. D isruption of this mindset is a lready underway. The tendency has involved a top down approach to employing renew able strategie s. Due to their high profile, the most likely adherents to this philosophy are managers of massive private, and public projects. Large private enterprises posses s detailed organization and cohesion, with sophisticated procurement streams. G overnment controlle d schemes are mandated by evolving regulation. W hat sort of persuasion might be effective to communicate benefits recognized by the government and large cont ractors? An Ashby chart (CES/Granta 2010) would very informative to the technically minded. This cartological evidence indicates material qualities on a continuum between two axes. These axes can be defined by any number of interactive properties includin g cost, strength, and conductivity. Suppose a building project were taking place in California. There definitely would be legitimate seismic issues involved with any kind of construction in this region especially if residential housing were involved For the purposes of this comparison between concrete and polymer use, fracture toughness would be a beneficial property even at the Looking at the chart more closely it may be observed that the y axis indicates r esistance to cracking, with the x axis measuring stiffness. Polymers are denoted by blue, concrete by yellow. The general disposition indicates polymers are exponentially less susceptible to damage from earthquake, through fracture, than concrete. In terms of actual field conditions, this finding would argue that a lighter structure made of plastic would probably be more suitable than one of heavier concrete A conventional concrete foundation home built in this area could only hope to equal flexural perfor mance of the polymer through utilization of an expensive rocker/jack system.
45 Marketing Plastic Homes So much for technical analysis regarding the benefits provided by plastics. T he appearance of a house constructed from the material c ould really arouse int erest. A polymer residence would be feasible though a great deal of development in technique may be necessary There are certainly situations where the polymer option has been seriously explored. The market will bear other possibilities than those driven by concrete. Entrepreneurially motivated attempts to establish the idea of structural plastics are gaining in momentum in the public conscience One heavily advertised option is called Green Magic. The units are priced between $14,900 for a single bedroom to $119,000 to construct a four bedroom structure. The marketing emphasizes a it fabricated kit (Green Magic Homes, 2018) This presentation unfortunately plays to expectations of flimsiness and cheapness often associated with construction in plastics, because the core components are made of fiberglass. The home is designed to be insulated by the earth and thus characterized as an ecological statement. It is also designed to sit on a plot of land. A picture is cr eated of autonomous villages of these dwellings far away from crowded cities. The idyllic nature of that narrative is interesting when contrasted with the current trend in environmentalism favoring a density building model. In recent years sustainable plan ning has developed a strong tendency toward concentration of new building with in existing metropolitan entities. T his Green Magic Homes option can be viewed as a specialty item. Another promising possibility was written up in Forbes magazine ( Winkless 2016). The story described a businessman with an idea to build polymer homes from waste plastics. Prospective homeowners were slum dwellers in Latin America. The hopeful candidates collected useable polymer trash, with the positive effect of cleaning up their neighborhood, and gave it to the entrepreneur. The builder then used extruders to fabricate relatively quickly assembled
46 components for new modular housing. The cost of each home was approximately $5,200. The mood of the written piece was highly opti mistic private sector solutions to environmental problems. When reading the column more closely one may detect an undercurrent of guilt T he initiative appears to be more philanthropy than the result of hard boiled business decisions. Capitalists were usi ng their wits to deal with situations for which they may have been largely responsible. The company constructed the dwellings by winning a $300,000 prize in a New York The award has enabled this business to complete 42 with another 20 slated to follow. Sustainable construction is such a ubiquitous topic, and even a polymer discussion so wide ranging (in fact a lifelong field of study), that scope must be strictly controlled. The options just dis cussed, are revealing in their perfunctory qualities. When the specifics of earth insulated and temporary urban polymer structures are considered, long term solutions disappear. Both are indeed small private ventures to a niche market which use of thermose t prefabrication, though the similarity ends there. One option is urban based and intended as itinerant shelter, the other marketed to utopian suburbanites with somewhat bohemian sensibilities. Neither option is designed to supply a broad market. The cases above have been included to represent an utter paucity of real alternatives to concrete a crucial factor when holding transformative expectations. Any adoption of sustainable polymers would depend upon fundamental cultural change. Anything less than this would be ineffectual in dealing, for example, with the effects of climate change. O perating on the assumption that cost has a rough equivalence with materials use and construction processes, a United States Census Bureau graph (below) shows current build ing trends. The first two columns of the index indicate a large preponderance of private, residential,
47 and nonresidential categories that remain untouched by sustainable imperatives. In other words, this is th at would be the audience to convince. The graph ic makes one thing very clear, a wide deficit in adoption of sustainable strategies exists Furthermore, this represents a chasm of perception. It acts a barrier between those who perceive the need for change, and motivated to seriously consider alternatives, and those unwilling to concede that investigation is necessary. The construction industry is a cultural expression. Through the centuries, this culture has developed building styles and associated material choices with the aim of satisfying p retensions of fashion and functionality resulting in deeply ingrained societal traits. Post modernism in architecture has only served to reinforce this gilding tendency. There will be very difficult challenge s ahead when confronting those inherited values P otential effects of climate change could offer a sufficiently pressing case to warrant the effort Study of that question is well outside the scope of this paper. But, it can reasonably be inferred, a s has been stated previously, that change will be a ccomplished through the actions of many within a kaleidoscope of situations. The goal here is to further that process by focusing upon the fundamental underestimation of potentialities for plastics use hypothesizing limited issues that contain significan t elements of the central problem
48 Figure 3 1. Concrete stress strain graph. Anis, Mohamed Ali, Stress Strain Relationship for Concrete file:///C:/Users/Wolfgang%20Ryor/Desktop/StressStrainConcrete.pdf ____________________________ Figure 3 2. Polymer stress strain graph. https://www.e education.psu.edu/matse81/node/2109 By permission of Pennsylvania State University College of Earth and Mineral Sciences Open Educational Res ource license/Creative Commons Attribution noncommercial ShareAlike 4.0 international license.
49 Figure 3 Granta CES Textbook Granta CES Textboofile:///C:/Users/Wolfgang%20Ryor/Desktop/2 Materials Charts 2010.pdf Figure 3 4. walking bridge at the University of Florida student union.
50 Figure 3 5 USCB information of proportion of private to public construction. Permission: Press Release of United States Government; United States Census Bureau, April, 2018
51 CHAPTER 4 OBJECTIVE S Interrelated Hypotheses The discussion has thus far concerned a variety of issues surrounding mass adoption of sustainable practices highlighting the situation of polymers. Inherent problems have already been discussed regarding the perception of materials within a broad context of current attitudes. Th e main hypothesis this paper will seek to address is unproveable in this brief exam ination of a vast topic. It will be necessary to elaborate upon such a proposition to some degree, that prejudice favoring concrete suppresses consideration of other possibly m o re efficient, alternative s. It has been argued that the concrete issue is repr esentative of general attitudes which may hamper adoption of broader sustainability policies. Interrelated, and much more manageable, hypotheses will be advanced, necessary to frame some of those persistent beliefs. Consequently, the chapter addressing sug gestions for further research and limitations of method s will assume a pivotal role. The intent is to propose, define, and prove understandable hypotheses, exposing misconceptions which could invite more incisive examination of sustainable alternatives. A Limited Hypothesis using Contour Crafting Among those more limited questions are polymer and concrete use within a n automated process touted as a significant development in sustainable construction The delivery method of Contour Crafting wil l be explored Front end material costs for a proposed structure will be estimated. The unit cost of the exact concrete amalgam dispensed in the Contour Crafting process cannot be accomplished, due to its proprietary nature. However, a reasonable facsimile can be deter mined for comparison purposes. The situation concerning polymer estimation uses similar modeling. The manufacture of this material depends upon propagation of the desired
52 molecular matrices. It would be preferable, though not essential, to design a thermoplastic with a high crystalline percentage This would greatly increas e resistance to applied stress through heat treatment. The hypothesis to be proven will demonstrate that molten polymer fabrication would produce structural properties, when utili zed within an automated process, that are equivalent to concrete amalgam. Examination of unit cost and infrastructure will also be addressed as factors. The next hypothesis will involve the nexus between perception and marketing decisions, to be reiterated with testing. The Marketing of Faux Wood Another subsidiary hypothesis will assert that faux wood is, in common practice, a decorative item. Manifold examples of structural applications for this material could be cited. It is, after all, plastic, a chemis try known for tunability. This argument will be advanced through research and testing. Focus will fall particularly upon cultural attitudes. Expectations of the utility of faux wood in the public consciousness will be presented within an advertising matri x. Laboratory work will emphasize these points. Concrete Versus Cementitious Material A hypothesis closely connected to that of faux wood will address qualities of cementitious materials, alongside those of concrete. The intention will be to draw out, and analyze, similarities and distinctions between the two. The assertion will be that similarities far outweigh differences. An Aside into Competing Life Cycle Claims Polymers are made of hydrocarbon chains, generically called petroleum, or crude oil. That fa ct would tend to raise competing claims surrounding life cycle costs. Although this discussion will fall within suggestions for further research, it will now be dealt with in a cursory manner. These are to be contentious points and may only be introduced a s subtexts of the main
53 hypothesis. Yet, it would be prudent to at least mention the argument. There are many facets to the life cycle and sustainability calculus. Manufacturing and transportation figure prominently. The raw crude is usually trapped within There are three primary stages of supplying the commodity F irst it must be drawn to the surface. The familiar geyser analogy would not present an accurate picture. Derricks have become very sophisticated due t o possible leaching. The British Petroleum disaster off the coast of Louisiana in 2010 need only be remembered to explain that danger. After extraction, t he resource is take n, usually by conventional bulk transport to the refine ry This is accomplished by myriad steps of addition and purification depending upon end use. It is noteworthy that many plastics are the last remnants of the process and readily available for recycling, due to the refining infrastructure. The fluid is then distributed across regio ns and continents. Life Cycle of Concrete It could be argued that c oncrete is relatively less renewable than polymer, owing to supply demands associated with mixture sourcing. Its composit e form can require prodigious quantities of Portland cement, sand, and aggregate rock not to mention additives All these components must be independently obtained. A common perception is the ingredients are natural C ement for example, is viewed by most as environmentally friendly. A closer look from an emb odied energy perspective renders quite a different verdict. Polymers are ever increasing in the mix, as fibers and polymerized sands. That would mean those items could only be recovered for recycle at end of life use, digging through tons of concrete and complicating any recycling pattern. This was discussed in th e introductory chapter when analysis was made of FDOT strategies.
54 Portland Cement Portland cement alone travels a variegated path to combine in recipe with other ingredients The Portland Cement Association (PCA) describe d their product as closely controlled chemical combination of calcium, silicon, aluminum, iron limestone, shells, chalk marl combined with shale, clay, slate, blast furnace slag, silica sand, iron ore T he PCA also comment ed environmental policy Highlighting employment of polymerized refuse, the group I t wa s also asserted that the group had become an adherent to l ife cycle a ssessment. To co unt the procurement streams described a total of 14 would be rendered, assuming they were all independently sourced and not part of a further level of manufacturing and collection. At least three levels of manufacture would be suggested by th eir descripti on : 1) processing of iron and steel ore which would incidentally supply polymerized recyclables; 2) the manufacture of concrete itself ; and 3) manufacturing within the Portland cement factories. Consideration of Figure 4 1 could also bolster the argument for plastic ( Granta/CES 201 0 ). This graph displays flexural strength against relative cost. I t seems to greatly favor concrete ( narrow yellow ellipse, lower left corner ), showing its low er cost However, lack of tensile resistance without reinforcement de mote d the composite far ther down the strength axis. When compiling the distortion, the fact is that unit cost, at purchase, provided the basis for cartological reference. More Accurate Assessment of Materials Costs reducing the impact of embodied energy is to (CSIRO, 2015). This statement from an Australian government manual
55 definition. It made clear th e fact that a full and accurate life cycle assessment must be taken into That diagram in Figure 4 2 indicates true relative value with weight given to dispos al costs after that graphic front end unit cost per volume constituted the baseline. A significant challenge to th e prospect of proper assessment of the lif e cycle are constructability concerns and a chauvinistic attitude about m aterials. Examination of a regular complaint used to reject plastics, their non biodegradability, gives further insi ght into weaknesses in consensus opinion. Thermop lastics are curre ntly recycled on a mass scale Functional barriers to inclusion of structural plastics only consist of logistics. The will to establish correlative integration of structural plastics into the mainstream presents the real obstacle. If polymer buildings and residences were a regular feature i n the construction industry, then infrastructure to re purpose expired comp onents would surely follow. This would, in turn, spur evolution of substantial efficiencies in a moribund recycling dynamic. Resultant synergy wou ld be crucial for evaluati on of back end costs. Present efforts to quantify this expense can be highly inaccurate, or absent altogether. Recycling infrastructure must not only prove efficient, but ultimately sustainable, in practical terms. Current problems with recycling are attributable in significant measure to this lack of coordination an d ingenuity. Using extrusion of concrete amalgam in Contour Crafting as an example, the paste could inclu de polymer fibers in support of tensile resistance. It h as already been argued that creation of efficiencies in retrieval and recycling mechanisms of these polymer elements is more difficult because the material is encased by concrete. It is generally assumed that concrete will eventually decompose to its natur al composite components while plastics will
56 not. The contradiction of this perception is self evident; polymers are set up to to be nonrenewable in that scenario. Circular logic is employed as proof. This anti recycling tendency is exacerbated by the prod uction of Portland cement The central concrete component can only be manufactured with copious amounts of alkaline and non alkaline metals combined with metalloids and pure metals. This is often the problem with accurate life cycle assessments i.e., in accurate metrics. Portland cement manufacture has a limited capacity to reduce its carbon footprint. Furthermore, the attitude supporting this effort axiomatically discourages retrieval of polymer additives. Despite pronouncements to the contrary, t here is no escaping a profound level of waste within this inherently cumbersome process. With all this said, t he econo my is structured to support these labor intensive and inefficient practice s Concrete is not a bad option, particularly in the short to medium t erm due it. This dependence does not just include building methods, but also labor and business relationships. A smooth transition away from this dependence is possible through positive use of technology. A tactic towards thi modalities like environmentally lean concrete. A periodical article (Plastics News Europe 2014 ) described that emergent economic role and made made effo rts to promote the combination of detritus (discarded plastics for instance) into the mix. This would lessen the environmental impact of the composite, while maintaining the current ubiquity of use. The logic of these actions is akin to the Latin America n example discussed earlier; the assumption is that polymers are junk and concrete is perfectible. This twist of reasoning has been Merely
57 criticiz ing the concrete indu stry as a wasteful enterprise in need of overhaul is therefore insufficient While the cement manufacturers raising LCA as a standard worthy of praise is somewhat disingenuous, it is probably essential to the transitional process. T he concret e industry mak es a fundamental contribution to society. Given time and education, opinion could begin to understand that digging giant hol es in the earth is not sustainable. Developers may then perceive that mining numerous elements for the sake of creating a historical ly preferred material is a damaging proposition. Then, if society persists along this line, even the most recalcitrant may sense investment in a costly industry, which annually emits five percent greenhouse gases (Plastic News Europe 2014), has acceptable alternatives. The purpose of this research is to give ammunition to that educational process. The goal is to oppose myopic tendencies and the correlative polarization of opinion. A common error when attempting to explain partisan positions on the topic is a retreat to diametrically opposed viewpoints. Inertia surrounding adoption of incremental environmental policies is often a result of simple bickering. Yet, beyond this type of conjectur e, a way forward can be found. M echanisms which dete rmine acceptability of emerging technologies and new uses of materials can play a significant role in adoption of sustainable processes The pressure of climate change, shifting demographic concentration, and disrupted patterns of productivity, are powerfu l drivers of change. Their operati on, over decades, could create an ever increasing momentum toward adoption of these strategies. Therefore, the time horizon is critical to the hypotheses advanced
58 Figure 4 1. Flexural Strength against Relative Cost Figure 4 2. Back end energy costs of materials.
59 CHAPTER 5 RESEARCH METHODOLOGY Lab work consisted of compressive and flexural testing of concrete, cementitious material, and faux wood. A cementitious mix makes ample use of polymerized, or burned, products of cement manufacturing. Examination of faux wood involved two primary morphologies, structural and decorative. The purpose of these selections was to test the limited hypothesis that, although structural faux wood could be delivered as a single component, cultural attitudes demote it to an accessory covering for concrete. The first morphology was molded, in shape and texture, as a plank in the deck of a walking bridge at the Univ ersity of Florida. The material was not tested by this researcher, but was representative of a structural component with expected results. This was based on results, cited in the Results chapter, of composite faux lumber testing by the Colorado DOT in 2000 (Janowiak 2000). The planks of the bridge were most likely composed of a block copolymer of two macromolecules in chain closed cell alternating configuration. This property would have provided strength through density but may possess a brittle quality The exact chemical composition was proprietary, though the material was quite possibly a high percentage, semi crystalline thermoplastic. To support this view, the other faux wood option was decorative, mimicking a beam. It was composed of regular polyure thane foam. This material was subjected to compressive analysis. The goal was to determine the structural properties of a commercially purchased channel, or hollow section product, and then extrapolate those data into the hypothesis described above. Concre te The concrete was obtained through a specific mixture, making use of FDOT #89 coarse aggregate, due to a limited size yield of 0.1 cu ft. to create specimens to fit an Instron 5969
60 Universal Testing Machine. Procedures of ASTM C192 16a (ASTM 2016) were f ollowed to insure proper mix control quantities and curing: 3.00 lbs. of Portland cement; 1.47 lbs. of water; 5.73 lbs. of #89 coarse aggregate; 3.63 lbs. of fine aggregate; 1.20 mL, Darex AEA; 2.70 mL, WRDA 60. The ingredients were placed in a standard mi xer. First all coarse aggregate and half the water were added, with 20 seconds allowed to mix. All the fine aggregate was added next, with another 20 seconds allowed to mix. Then all Portland Cement and the other half of the water were added last. All ingr edients were then allowed to mix for three minutes; the mixture was then set in ten miniature molds, secured within plastic and let stand in the lab for 24 hours. After that time had elapsed, the ten molds were submerged in an aqueous solution of 2.67 L, i for adequate curing. the proper sample number and group distribution for the concrete Originally, it was intended that 1 0 specimens would be used to calculate standard deviation (s) and tolerance (r=2.8 x s) providing the representative sample. The resource equation for that scenario read; N T = E; 10 0 = 10 The decision was made to test one group of t en specimens providing standard deviation and tolerance. Because the material was mixed composite concrete, given to greater variance than a manufactured product, one group of ten specimens was tested. The specimens were subjected to a single modality, fl exural measurement using third point loading. All laboratory activities were performed according to ASTM C78 18 (ASTM 2018) procedures. The same Instron5969 Universal Testing Machine was used. After thirteen days of curing, the specimens were removed from the solution and allowed to dry for 20 hours. Preparation of t he specimens for the extensometer was accomplished through
61 progressive sanding and each was measured for its planar area cross section. The roughness of the surface caused by the nature of the material, regardless of careful preparation, was anticipated to involve possibly extensive lag inertia values. The actual test was performed by this researcher, supervised by an expert, at 115 Rhines Hall, in the Lattice Lab, on the University of Florida campus in Gainesville. The date was July 2, 2018; the time, 10:00 a.m. to 6:30 p.m. EDT The room temperature was 72 73F with a Relative Humidity of 34 37%. Ten specimens were measured for thickness and width with a digital caliper, across each cross secti onal area, and for length. The compressive, three point bending technique (TPBT) parameters and method were entered and calibrated through Bluehill3 software into the Instron5969. Appropriate dimensions were entered into the computer, following ASTM D695 1 5 (ASTM 2015), for each. Compression rate was set at 0. 05 0 in./min. for each; stress and strain were recorded graphically and quantitatively. The compressometer was set at 23 .0 mm (0.906 2 in.) between two fixed points, and was judged visually, to minimize lag inertia when specimens were aligned with the compression tool plunger. The Instron 5969 provide d applied force and displacement measurements for each specimen. All those data were stored in a computer file for each specimen. Values for stress, strain, a manually calculated through insertion into equations : = = = Deflection was also calculated for concentrated and uniform loading Cementitious Material The cementitious material was prepared (Tackey Otoo 2018), following FDOT Section 346 (FDOT 2005) and ASTM C78 18 (ASTM 2018) standards. Slag and Pozzolans (fly ash) compliant with Section 929 requirements was prepared as a cement replacement as specified in Section 346 2.3. (FDOT 2005) The mixtures, who se results are enumerated in the following chapter, were composed of the following proportions:
62 Binary A mixture, consisting of 80% Portland cement and 20% fly ash; Binary B mix was also cast, with proportions of 50% Portland cement and 50% slag. Anothe r mix, called Ternary A, was cast containing 50% fly ash, 30% Portland cement, and 20% slag. The last was the only sample with cement as the admixture. A mong the materials tested, it most accurately represented the lowest allowable flexural strength capab ilities of FDOT sanctioned cementitious material. This was due to the extent to which polymerized sands were included in the mix. Deflection was also determined in this manner using those data recorded by that researcher. This researcher extrapolated those deflection data into concentrated and uniform loading figures. Faux Wood The faux wood was commercially purchased from Home Depot for a price of $109.00, excluding tax, with cross section dimensions, in channel form, of 2.50 in. X 3.50 in., and a thickness of 0.50 in. X 0.75 in. respectively. The length of the beam was 9.00 ft. 10.00 in. The decorative faux wood beam supp lied seven specimens extracted from a localized area of approximately 2 .50 in. X 7 .00 in. X 5 .00 in The general dimensions of that area approximately 1/18 of beam length, were selected to minimize any differences within the polyurethane lattice material. esource equation was employed to determine the proper sample number and group distribution for the faux wood Originally, it was intended that 1 0 specimens would be used to calculate standard deviation (s) and tolerance (r=2.8 x s); providing the represent ative sample. The resource equation for that scenario read : N T = E; 10 0 = 10 The decision was that one group of seven specimens was to be used providing standard deviation and tolerance. The determination was made that this number would be sufficient due to utilization of only a
63 singular modality, compressive measurement (T), on the Instron5969 Universal Testing Machine The specimens w ere cut with an Exacto knife and close quarters hacksa w, and then dimensioned through progressive sanding. Each was measured for its planar area cross section. These values were manually calculated = = = Deflection was also determined. Th e actual test was performed by this researcher, supervised by an expert, at 115 Rhines Hall, in the Lattice Lab, on June 8, 2018 from 9:00 am to 10:00 am EDT. The room temperature was 72 73F with a Relative Humidity of 34 37%. Seven specimens were caliper measured for thickness and width, across each cross sectional area, and for length. The compressive, three point parameters and method were entered and calibrated through the Bluehill3 software on the Universal Testing Machine. Appropriate dimensions were entered into the computer, following ASTM D695 15 (ASTM 2015), for each. The Instron machine provide d applied force and displacement measurements for each specimen. The compressometer was set at 23 .0 mm (0.906 in.), between two fixed points, judged visual ly, to minimize lag inertia when specimens were aligned with the compression tool plunger. Compression rate was set at 0.05 0 in./min. for each, with stress and strain recorded graphically and quantitatively. All those data were stored in a computer file fo r each specimen. Contour Crafting The Contour Crafting process was utilized to generate cost information, in general terms, because specifics were proprietary. Still, sufficient textual sources did exist to provide accurate background to simulate volumetr ic values needed to construct a simple structure. This process would entail a Contour Crafting gantry depositing amalgam or molten polymer to create walls in three layers: 1) interior face 2) the core and 3) exterior face. It is important to note that a po lymer extruded from the gantry would possess properties roughly equivalent, if not superior, to
64 concrete amalgam; dispensed from identical equipment. If weight were added to the list, the ideal properties would closely resemble autoclaved concrete blocks. However, the delivery method for material with its own complicated processing (Kosmatka et al 2008). The interior wall was used in this example for the di mensions of 5. 00 in. X 10.0 ft. X 10.0 ft. Material takeoffs were included to value the 45 zig zag core, and the exterior face as well. The illustration below gives an accurate picture of the density generated in the construction process. This Revit struc ture, created by the author, is not exactly to scale (wall thickness), and excludes depiction of the roof, which is merely another exterior face covering the cube. This was intentional, to graphically illustrate the simplicity of the model, for purposes of comparison. It followed that fenestrations within any surface were omitted. The scenario by which different extruders for wall construction were set upon the Contour Crafting gantry production reduced the mechanism of delivery to a single variance. The p olymer extrusion for the envelope was presumed to have been performed through a machine which had sufficient protection for molten gel tolerance through selection of properly protected trowel material, while the concrete amalgam would have exited the nozzl e as a paste. It was further presumed that equipment to place the systems linkages into the wall core would employ the same process in both cases, negating consideration of that minutiae.
65 CHAPTER 6 RESULTS Findings were divided into three parts from co mpressive testing employing a three point bending technique (TPBT). Stress and strain were measured for concrete, cementitious mixtures, and faux wood. The cementitious sample was tested by a colleague who provided unpublished information (Tackey Otoo 2018 ). Concrete and faux wood were subjected to three point compression, utilizing an Instron5969 Universal Testing Machine. Both tests followed ASTM appropriate C and D procedures. Faux Wood Compressive Strength Testing Results per Specimen Specimen 1 ruptured while secured within the compression tool. This was probably due to operator manipulation of crosshead movement. Initial measurements were being provided by the machinery. It was ascertained that contact force had skewed any values deri ved from the software and the specimen test was terminated. Specimen 2 did not settle immediately. This was exhibited through a consistent 0.124 in. displacement from test inception. This figure was subtracted from strain measurements around the yield poi nt. It is important to note that this did not represent an offset; described in ASTM D695 15 (3.2.11). Rather, it was attributed to load inertia lag, described in ASTM D695 15 (5.1.2). The inflection point was demonstrated, as with all the specimens, quant itatively. Offsets, determined through ASTM procedures graphically chart yield point on a stress strain curve. Inflection, or yield point, occurred at 205 seconds. The force level indicated 12. 1 lbs. Displacement indicated was 0.29 5 in. The inertia lag was subtracted from that of the yield point figure. The result was 0.17 1 in displacement. Specimen 3 was placed incorrectly upon the compression tool base. The consequent imbalance, caused when the plunger descended, ruptured the specimen.
66 Specimen 4 was loa ded according to procedure. Inertia lag was virtually nonexistent at minus 0.006 in. Inflection occurred at 270seconds, with 22. 1 lbs. of force, and 0.219 0 in. displacement. Inertia lag was subtracted. The result was 0.21 7 in. displacement. Specimen 5 load ed with the most substantial amount of 0.435 in. inertia lag, and spoiled. The operator had not adjusted the parameter setting in Bluehill3. This feature of the software determined the level of each measurement, depending upon the desired information from the test. The operator also had not checked the parameter of loading speed. Thus, the rate of loading was accelerated by default. If any parameters for any specimen were not set, they would default to a preset value. The default displacement had been set t o terminate the crosshead movement at 0.50 in. Therefore, the attempt to complete testing this specimen ended when displacement quickly reached 0.50 in. Specimen 6 loaded with the substantial amount of 0. 455 in inertia lag. The error that had occurred wi th the prior specimen had yet to be discovered. In this instance as well, the operator had not adjusted the parameter setting in Bluehill3. The rate of loading was accelerated by default. The default displacement was set to terminate the crosshead movement at 0.50 in. However, the crosshead fell too quickly. This was the cause of the rupture that terminated the test. Specimen 7 loaded with a very satisfactory lag inertia of zero. Inflection occurred at 21 2 seconds, with 0.176 in. displacement, and 13. 2 lbs. of force. The specimen ruptured at this maximum loading. Inertia lag was subtracted. The result was 0.176 in. displacement Analysis showed there had undoubtedly been problems with setting of the compressometer, and the technique of accurately placing the specimens. Furthermore, constant repetition in resetting parameters through Bluehill3 was also lacking. The discrepancy in findings, especially of
67 values derived from compressive testing are listed in tabular form below. Concrete Compressive Strength Testing Results per Specimen Specimen 1 loaded with substantial lag inertia of 0.232 in. Displacement at rupture was 0.253 in. at 102.5 lbs. of applied force. Specimen 2 loaded well. It experienced lag inertia of 0.00 9 in. Displacement at rupture was 0.026 in. at 17 0 lbs. Specimen 3 was loaded improperly and experienced lag inertia of 0.036 in. This was due to the coarseness of the specimen. The resultant slippage within the compressor tool caused continued negative displacement, causing rupture at 0.011 in. at 54.0 lbs. Specimen 4 loaded with a reasonable lag inertia of 0.122 in. Displacement at rupture was 0.148 at 1083lbs. Specimen 5 experienced a lar ge lag inertia of 0.441 in. Displacement at ruptu r e was 0.453 in. at 812lbs. Specimen 6 loaded slowly with lag inertia of 0.128 in. Displacement at rupture was 0.138 in. at 67.4 lbs. Specimen 7 experienced a similarity in lag inertia to Specimen 5, at 0. 437 in. Displacement at rupture was 0.453 in. at 528lbs. Specimen 8 was unable to load into the compression tool properly due to unacceptable coarseness. Therefore, the stress strain curve was too inaccurate. Specimen 9 loaded promptly at 0.010 in. Displ acement at rupture was 0.319 at 139lbs. Specimen 10 results were inaccurate because the right end of the specimen had crumbled causing deformation that excluded placement into the compression tool. These measurements, summarized in Table 6 1 clearly demonstrate the axiom that uniform force more effectively than concentrated properties. Cementitious material also exhibits this trait. The polymer, on the other hand, will possess a more limited modulus of elasticity, so uniform loading resistance will be l e ss than that
68 of concentrated loading. More discussion of these features will follow in the Conclus ions chapter. Figure 6 1. Calculations for polymer gel and concrete amalgam volumes. Figure 6 2. Core wall unit construction [166.68 ft 3 ] + [164.98 ft 3 ] + [237.94 ft 3 ] = 569.60 ft 3
69 Figure 6 3. Revit image created by author. Faux Wood* Concrete Comparative Ratio 2 28 0,000psi 2 5 00,000psi ** Polymer ( 10:11 ) Tensile Strength (F b ) 7860 psi 300psi ** Polymer ( 26 :1) structural composite lumber (Janowiak et al. 2000) ** commonly accepted properties Figure 6 4. Expected physical properties of structural faux wood and concrete.
70 Unit Cost Quantity COST Concrete Amalgam (ft 3 ) $30.00 569.6 $17,088 Plastic Gel (ft 3 ) $67.00 569.6 $38,163 Polymer Sigma Aldrich Figure 6 5. Unit cost comparison between generic concrete amalgam and a given structural polymer, ordered from Sigma Aldrich. This was purposely done to highlight the costs and benefits of infrastructural support.
71 Table 6 1. Summary of materials properties. Concrete Specimen #/Area (sq. in.) =P=V (lbs.) Flexural Strength (3V)(d)/(2A) Modulus of Rupture ( (lbs./sq. in.) (lbs./sq.in.) Deflection (in.) Deflection (in.) ** L (in.) Strain (in./in.) W @ Fx (in.) (t) (in.) 1/1.99 102 77.6 SQ 408NCD 0.36 0.28 2.03 0.13 1.97 0.98 2/1.99 171 114 SQ 6614NCD 0.03 0.03 2.00 0.01 1.94 1.00 3/1.63 54.0 2.00 1.94 0.82 4/1.39 1084 2273 SQ 10,371NCD 0.43 0.31 2.00 0.08 1.94 0.70 5/1.07 813 3935 SQ 11,843NCD 0.81 0.56 2.10 0.06 2.03 0.52 6/0.46 67.4 658 *** 2407NCD 0.79 0.56 2.26 0.06 0.78 0.57 7/0.54 528 5856 7369NCD 1.65 1.16 2.05 0.22 1.06 0.50 8/0.50 0.10 9/0.37 139 2709 23,740NCD 0.21 0.17 1.99 0.02 0.69 0.46 10/0.56 229 1566 7498NCD 0.06 0.64 Binary (A/28)/16.0 3728 723 2,716,000 (cylinder data) 0.0 23 0.0 17 12.0 0.002 4.00 4.00 Binary (B/3)/16.0 2830 549 12.0 NSD 4.00 4.00 Ternary (A/28)16.0 1668 323 12.0 NSD 4.00 4.00 FW2/ 0.21 12.0 1335 677NCD 1.16 1.25 1.35 0.08 0.56 0.25 FW4/ 0.20 22.0 1276 770NCD 0.96 1.02 1.50 0.15 0.55 0.35 FW7/ 0.18 13.1 847 590NCD 0.63 0.67 1.44 0.12 0.51 0.36 *Uniform Load Presumed **Third Point Load Tested NCD=Non Cylinder Data NSD=No Strain Data FW=Faux Wood SQ=Square and Planar ***Most Uniform Beam (No Ridge)
72 CHAPTER 7 LIMITATIONS AND SUGGESTED FURTHER RESEARCH In this analysis, many topics have been excluded, or simplified. P ursuing them would serve no impo rtant function. Avoidance of c omplex ity has been the rule regarding materials and structural issues. The methodology has been to examine a large complex topic through hypotheses of more limited natu re. The intention has been to break the main hypothesis into smaller pieces to aid in analysis. This has been achieved through utilization of elements that promote clarity in multifaceted situations, culminating in illumination of specific context by extra polation into broader themes. It has also been necessary to curtail addressing peripheral components that detract from essentials. An attempt to define political players was necessary, though minimization of such commentary was exercised as much as possibl e. The intent was not to ignore such a pivotal influence. Instead, a stance against obfuscation has been assumed. Scenarios depicting tectonics between striving brokers of opinion were avoided, while an effort was made to accurately portray the goals of th ose actors. Returning to the main question, large scale replacement of structural concrete with polymers would be somewhat paradoxical. The progression would first entail a relatively straightforward chemistry problem. There is little doubt that, in relati ve terms, obtaining those properties would be employed via the simple recourse of ordering the material from manufacturing and distribution giants. Sigma Aldrich has been used, in that role, for comparison of unit costs. Furthermore, it was determined that intricate laboratory testing of the exact compounds was extraneous, if not impossible. Far more mysterious would be the means and ways in which consensus in the construction indust ry, and society, could embrace such a solution It has been asserted that cultural attachment to traditional building habits are very specifically marked, having
73 institutionalized social and economic relationships over the past few hundred years. Change of supply and transportation infrastructure, contractual provisions, and lab or organization will be just a few of the targets of innovation. Specific transitional achievements will provide a fertile field for potential study. A cultural learni daily lives. That process is in its infancy, as evidenced by the impatience of advocates. Solutions and processes will evolve as variations are adopted, often through singular experim entation Individual choices will be judged according to effectiveness. Opinions of enlightened or regressive behavior should evolve from this experimentation. Therefore, examination of progressive development of current building trends in polymer housing over the long term could be very useful in identification of emerging societal attitudes. Monitoring of public discourse will also be important, to evaluate the relative proportion of plans based on political, rather than empirical, information. It would be valuable to monitor correlative labor aspects of structural plastics. Will resources and personnel be committed to creation of large scale recycling? Will there be measurable indications of synergy between producers, constructors and recyclers? Could e xtensive use of repetitive, and streamlined re sourcing processes be identified? Is there a growing shift of emphasis in labor deployment towards recycled deliverables, and, if so, at what rate? Are transitional paradigms in allocation of personnel and res ources present at all? At any given time, where could the current situation be placed within the beta curve of technological innovation? In short, study of the multifarious progression of polymer use as a structural material will prove a very potent tool f or monitoring transition.
74 Creation and extension of recycling infrastructure is already on the drawing board. Institutional support for these projects has been given by many governmental organizations and private parties. Re sourcing parameters are becomin g integrated into the text of standards and certification organizations, such as LEED, ANSI and the ISO. Protocols and documentation aimed at regularizing embodied energy feedback, Environmental and Health Product Declarations, Chemical Abstract Service Re gistration, extended producer responsibility programs, and many others, are continuously being fine tuned. Another topic marginally dealt with in this study was Contour Crafting. By necessity, only a few points about this exciting delivery method were high lighted. Propriety restrictions upon operational specifics also accounted for the limited treatment. Still, there will be ample research possibilities as automation technology expands, such as exploration of the extruded use of semi crystalline block thermoplastic in the Contour Crafting process would depend upon heat transfer properties. The material envisioned by this paper would have to be strong enough to support its own weight, but malleable enough to combine with p rior layers. This problem is common to 3D printing plastic (ABS) extrusion consistency is dependent upon control of temperature variation from the hot base of the model to the progressively cooler layers above. Such research is now pursued by a prolifer ation of companies. A firm called Celanese has experimented with injection of Boron Nitrate into polymers (Celanese 2018). This strategy would be less than ideal in terms of recycling. Considerable benefit could be derived from ascertaining whether the coo ling gel could hold adequate compressive force, without doping.
75 CHAPTER 8 CONCLUSIONS The author of this thesis has chosen to present the main hypothesis, a general prejudice against plastics in favor of concrete as a structural material, through the sp ectrum of limited proofs. The properties of widely marketed faux wood beams has been shown to confirm, to whatever degree, that polymer stability is widely dismissed. An argument with many limitations could be made that this quality determines infrastructu re of its supply. The proposition may be asserted that this is a self fulfilling prophecy. Plastics are flimsy because most of its manufacture is driven by decorative or accessory purposes. Demand must be satisfied because consumers value facile, throw awa y items. This situation closely resembles the kind depicted by Peter Norton (2008) in his e emergence of cement was the result of similar, cyclical, logic. Testing a sample of repeating unit polyurethane exhibited the representative lack of hovered arou Although that test made use of a beam shape, instead of a cylinder, the modulus of elasticity for that material would not significantly improve. Exaggerated deflection would only be replaced by excessive bowing off the centerlin e. Polymer lumber guardrails, that were not selected for decorative qualities, were likewise examined using test ary material was proven more than adequate to be used within the FDOT bridge pier pultrusion profile sections. The mixture of 20% easily have been a 50% 50% mix b etween slag and Portland cement. In fact, FDOT Section 346
76 2.3 allowed for such a mix, with 62% slag in drilled holes. This indicated the agency considered highly polymerized mixtures equivalent. It was shown that the public sector often used structural pl astics, and would increasingly do so, in place of metal and concrete. The intention of hypothesizing and studying the results of these limited questions was to demonstrate that they were not random or isolated, but constituted progressive usage of structur al plastics in the public sector. Private sector choices vastly deviated from the pattern. This dichotomy was further emphasized by compressive testing which demonstrated that polyurethane was conceivable to most casual observers, as only a covering for co ncrete or steel members In fact, it often goes unnoticed that bowling balls are composed of highly semi crystalline polyurethane and smash into pins and alleys. Still, though bowling balls are ubiquitious, these structural properties are not generally val ued. Connection of Uniform Loading with Deformation While analyzing polyurethane faux wood cementitious materials and #89 aggregate concrete, certain facts emerged. At first glance, the deflection of the decorative faux wood seemed to totally dismiss con sideration of any structural value. However, a recurrent theme of this research has been to encourage imaginative thinking for conventional materials. This polyurethane covering exposed the property of deflection, a factor worthy of a second look. In disco vering the true meaning of marked lateral displacement exhibited by decorative faux wood, Contour Crafting could be pondered. This automated, sustainability oriented, building method has been extensively utilized in this study as a tool of comparison. The central feature of delivery is extrusion of a structural paste or gel, from its computer guided gantry. This process has the effect of creating an exterior envelope composed of layer after layer of uniformly loaded beams. Furthermore, that dynamic increase s pressure on the lower layers of product, exacerbated by the
77 relative weight of the extrusion material chosen. As may be recalled from the Literature Review b elieved a light material was necessary to provide essential malleability, while maintaining sufficient stiffness. Hansmeyer applied the logic of 3D printing, where lower levels of extruded plastic are subjected to increased forces. In printing, the resulti ng material stresses arise from thermal properties, the heat of dispensed gel collecting at the base of the model. In gantry extrusion, stresses result from cumulative resistance to application of uniform weight. In both cases, a means should be developed to a void such deflection, pulling at each corner of the wall structure. This situation could create severe structural problems for a home extruded by Contour Crafting. It will be recalled from the revit model that 45 corners abound in that case, with zig zag cores enclosed by interior and exterior walls. The bench scenario from the Problem Statement described the same reinforcement situation. The question was whether bench material possessed sufficient deflection and associated internal displacement If no t, what measures would be necessary to achieve that support ? The tables at the end of the Results Chapter contained a similar expression, Beams will experience various l oading factors. A dead load of constant force along the entire length would be represented by the in the first equation; a point load, on a spot, would be indicated by in the latter. So, d eflection presents the key to understanding qualities of perf ormance of polymer cementitious materials and concrete extruded by Contour Crafting nozzles. It would be advantageous at this point to put two concepts together. It has been established that requisite stiffness is present in semi crystalline lattices, w ith application of proper heat treatment. Propagation can be controlled by the rate of introduction of the catalyst
78 insuring sufficient amorphous chains form to acquire the deflection properties possessed by decorative polyurethane. Concrete and cementitious materials composite does not exhibit nearly enough deflection, without failing, as performance s of the test specimens confirmed. This was further demonstrated by the axiomatic inverse relationship between the reaction of the respective mat erials to concentrated and uniform loading. Essentially, the concrete and cementitious materials can counter applied force with accu mu lation of uniform stress because they are much more rigid. Therefore, the y also exhibited weaker resistance to deflection under these loading conditions caused by the increased rigidity when confronted with uniform force L ack of deflection along the entire beam, due to this uniform resistance will eventually cause stresses at the corners, cracking and failure Polymers gre ater flexural qualities in response to this type of force application indicates a superior ability of walls constructed of that material to deflect instead of crack in a Contour Crafting home. Therefore, concrete amalgam must assume a largely cementitious mix proportion in the Contour Crafting process to approach those polyurethane flexural capabili ties. The figures obtained from the binary mixture established this fact by demonstrating the same characteristics, vis vis uniform loading stiffness and concentrated flexural capacity, as concrete Thus, t he limited hypothesis that cementitious material is nothing more than a compromise that perpetuates was proven in this detailed c ircumstance Regarding polyurethane, the brief stable linear relationship of stress and strain in compression, as demonstrated in this research, could be extended with a different proportion of crystallization within the same material. Such a foam would increase in density, as with bowling balls, without a prohibitive rise in overall weight. The actual constitution of that material would depend upon the scope of construction. Certainly, in a structural sense, this material wou ld
79 substantially resemble the faux lumber of the Colorado guardrails, or the bridge planks at the University of Florida. The exact chemistry would need further research than was possible in this investigation. The result, though, would also be axiomatic du e to properties so often discussed in this study. Once gel composition w as determined, information detailing the specific rate of molten extrusion could be programmed into the computer controlling the dispensing nozzle on the Contour Crafting gantry. The software will already have modeled the condition of extrusion to guarantee positive results. Thus, the limited hypothesis that molten polymer gel used in a structural role is at least as efficient as concrete amalgam and cementitious material when dispens ed through a sustainable automated delivery process, is likewise proven. It may be reasonably extrapolated from those data that the decision to use concrete amalgam doped with cementitious elements as the central feature in Contour Crafting was influence d by something other than the scientific method. This further extrapolation would necessarily pass into the realm of th e unprovable hypothesis in this research the specific nature of multifaceted and complex societal decisions.
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83 BIOGRAPHICAL SKETCH Wolfgang Derek Ryor was born in San Jose, California in 1963. He attended the University of California at Davis, graduating in August 1987 with a Bachelor of Fine Arts urance and municipal employment. Having felt the need to make an academic contribution, Mr. Ryor returned to school at Seminole State College, Florida, in January 2011. As a nontraditional student with extensive private and public sector experience, Mr. Ry or chose a field that incorporated both dimensions, construction. He graduated from Seminole State in August 2015 and then went on to study for a Master of Science in Construction Management degree at the M.E. Rinker Sr. School of Construction Management at the University of Florida This thesis is his first published work.