<%BANNER%>

Stormwater Filtration Properties of Pervious Concrete

Permanent Link: http://ufdc.ufl.edu/UFE0025013/00001

Material Information

Title: Stormwater Filtration Properties of Pervious Concrete
Physical Description: 1 online resource (52 p.)
Language: english
Creator: Farmerie, Sarah
Publisher: University of Florida
Place of Publication: Gainesville, Fla.
Publication Date: 2009

Subjects

Subjects / Keywords: concrete, filtration, pervious, pollutant, stormwater
Building Construction -- Dissertations, Academic -- UF
Genre: Building Construction thesis, M.S.B.C.
bibliography   ( marcgt )
theses   ( marcgt )
government publication (state, provincial, terriorial, dependent)   ( marcgt )
born-digital   ( sobekcm )
Electronic Thesis or Dissertation

Notes

Abstract: Stormwater runoff is a major source of concern as the percent of impervious surfaces covering the planet continues to rise because it causes physically and ecologically detrimental changes to nearby surface waterways. The United States Environmental Protection Agency offers a number of best management practices (BMP) to better control the effects of this runoff on the environment. Pervious concrete is considered a BMP for its ability to reduce the total volume of stormwater runoff. The purpose of this research was to examine the stormwater filtration abilities of pervious concrete made with limestone pea gravel (#89) and a variety of cementitious materials: Portland cement, granulated blast furnace slag, and fly ash. Using tests for porosity, permeability, and compressive strength on the concrete specimens, as well as data obtained about the physical properties of the stormwater before and after filtration by the concrete, it was concluded that pervious concrete made with mineral admixtures does effectively minimize the amount of pollutants found in the stormwater effluent. When the contaminated stormwater was allowed three days of contact with the pervious concrete specimens, there were significant reductions in the levels of nitrates and phosphates found in the stormwater. The dissolved oxygen levels increased with time, another indication of the beneficial effects of pervious concrete on stormwater runoff.
General Note: In the series University of Florida Digital Collections.
General Note: Includes vita.
Bibliography: Includes bibliographical references.
Source of Description: Description based on online resource; title from PDF title page.
Source of Description: This bibliographic record is available under the Creative Commons CC0 public domain dedication. The University of Florida Libraries, as creator of this bibliographic record, has waived all rights to it worldwide under copyright law, including all related and neighboring rights, to the extent allowed by law.
Statement of Responsibility: by Sarah Farmerie.
Thesis: Thesis (M.S.B.C.)--University of Florida, 2009.
Local: Adviser: Muszynski, Larry C.
Local: Co-adviser: Issa, R. Raymond.
Electronic Access: RESTRICTED TO UF STUDENTS, STAFF, FACULTY, AND ON-CAMPUS USE UNTIL 2011-08-31

Record Information

Source Institution: UFRGP
Rights Management: Applicable rights reserved.
Classification: lcc - LD1780 2009
System ID: UFE0025013:00001

Permanent Link: http://ufdc.ufl.edu/UFE0025013/00001

Material Information

Title: Stormwater Filtration Properties of Pervious Concrete
Physical Description: 1 online resource (52 p.)
Language: english
Creator: Farmerie, Sarah
Publisher: University of Florida
Place of Publication: Gainesville, Fla.
Publication Date: 2009

Subjects

Subjects / Keywords: concrete, filtration, pervious, pollutant, stormwater
Building Construction -- Dissertations, Academic -- UF
Genre: Building Construction thesis, M.S.B.C.
bibliography   ( marcgt )
theses   ( marcgt )
government publication (state, provincial, terriorial, dependent)   ( marcgt )
born-digital   ( sobekcm )
Electronic Thesis or Dissertation

Notes

Abstract: Stormwater runoff is a major source of concern as the percent of impervious surfaces covering the planet continues to rise because it causes physically and ecologically detrimental changes to nearby surface waterways. The United States Environmental Protection Agency offers a number of best management practices (BMP) to better control the effects of this runoff on the environment. Pervious concrete is considered a BMP for its ability to reduce the total volume of stormwater runoff. The purpose of this research was to examine the stormwater filtration abilities of pervious concrete made with limestone pea gravel (#89) and a variety of cementitious materials: Portland cement, granulated blast furnace slag, and fly ash. Using tests for porosity, permeability, and compressive strength on the concrete specimens, as well as data obtained about the physical properties of the stormwater before and after filtration by the concrete, it was concluded that pervious concrete made with mineral admixtures does effectively minimize the amount of pollutants found in the stormwater effluent. When the contaminated stormwater was allowed three days of contact with the pervious concrete specimens, there were significant reductions in the levels of nitrates and phosphates found in the stormwater. The dissolved oxygen levels increased with time, another indication of the beneficial effects of pervious concrete on stormwater runoff.
General Note: In the series University of Florida Digital Collections.
General Note: Includes vita.
Bibliography: Includes bibliographical references.
Source of Description: Description based on online resource; title from PDF title page.
Source of Description: This bibliographic record is available under the Creative Commons CC0 public domain dedication. The University of Florida Libraries, as creator of this bibliographic record, has waived all rights to it worldwide under copyright law, including all related and neighboring rights, to the extent allowed by law.
Statement of Responsibility: by Sarah Farmerie.
Thesis: Thesis (M.S.B.C.)--University of Florida, 2009.
Local: Adviser: Muszynski, Larry C.
Local: Co-adviser: Issa, R. Raymond.
Electronic Access: RESTRICTED TO UF STUDENTS, STAFF, FACULTY, AND ON-CAMPUS USE UNTIL 2011-08-31

Record Information

Source Institution: UFRGP
Rights Management: Applicable rights reserved.
Classification: lcc - LD1780 2009
System ID: UFE0025013:00001


This item has the following downloads:


Full Text

PAGE 1

1 STORMWATER FILTRATION PROPERTIES OF PERVIOUS CONCRETE By SARAH MACE FARMERIE A THESIS PRESENTED TO THE GRADUATE SCHOOL OF THE UNIVERSITY OF FLOR IDA IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE DEGREE OF MASTER OF SCIENCE IN BUILDING CONSTRUCTION UNIVERSITY OF FLORIDA 2009

PAGE 2

2 2009 Sarah Mace Farmerie

PAGE 3

3 To my family and friends who supported me along the way I love you

PAGE 4

4 ACKNOWLEDGMENTS I would like to thank my committee: Dr. Larry Muszynski, Dr. R. Raym ond Issa, and Dr. Svetlana Olbina, for their guidance and suppor t throughout my research. I appreciate the generosity of W.W. Gay Mechanical Contractors, who donated the mechanical parts to construct the falling head permeameter for this researc h. Also, without the assistance of the Florida Department of Transportation, especially Mr. Cr aig Roberts and the conc rete testing laboratory, aspects of this research would not be possibl e. Jane Mace and John Hendrickson of the St. Johns Water Management District provided invalu able insight into the contaminated waterways of North Florida. On a more personal level, I am forever grateful for Kristyna Lannons friendship, encouragement, and advice, particularly throughout this process. My parents, Drs. William Farmerie and Jennie Mace, also deserve more gratitude than can be expressed for their endless support, from allowing me use of their workshop to taking care of my baby, Gravy. Finally, I am thankful for the love, patience, humor, a nd unwavering optimism of Tony Marquez.

PAGE 5

5 TABLE OF CONTENTS page ACKNOWLEDGMENTS...............................................................................................................4 LIST OF TABLES................................................................................................................. ..........7 LIST OF FIGURES.........................................................................................................................8 LIST OF OBJECTS.........................................................................................................................9 LIST OF ABBREVIATIONS........................................................................................................ 10 ABSTRACT...................................................................................................................................11 CHAPTER 1 INTRODUCTION.................................................................................................................. 12 2 LITERATURE REVIEW.......................................................................................................13 Stormwater Runoff.............................................................................................................. ...13 Alternative Water Management Systems............................................................................... 14 Pervious Concrete as a Be st Management Practice................................................................ 14 3 MATERIALS AND METHODOLOGY................................................................................ 17 Materials.................................................................................................................................17 Coarse Aggregate............................................................................................................17 Cementitious Materials.................................................................................................... 20 Design, Fabrication, and Curing of Pervious Concrete Specimens........................................21 Mix Design Proportioning............................................................................................... 21 Mixing and Pouring Concrete Samples........................................................................... 22 Compaction Methods.......................................................................................................23 Curing Process.................................................................................................................25 Hardened Concrete Testing....................................................................................................25 Specific Gravity, Volume of Voids, and Porosity........................................................... 25 Permeability................................................................................................................... ..26 Compressive Strength...................................................................................................... 28 Stormwater Filtration and Testing Methods........................................................................... 29 Initial Testing...................................................................................................................30 Water Composition Change Over Time..........................................................................31 4 DATA ANALYSIS................................................................................................................ 32 Hardened Concrete Test Data.................................................................................................32 Specific Gravity, Volume of Voids, and Porosity........................................................... 32

PAGE 6

6 Permeability................................................................................................................... ..33 Compressive Strength...................................................................................................... 35 Stormwater Filtration Data..................................................................................................... 36 5 CONCLUSIONS AND RECOMMENDATIONS................................................................. 40 Conclusions.................................................................................................................... .........40 Recommendations................................................................................................................ ...41 APPENDIX A PERVIOUS CONCRETE TEST SPECIMENS..................................................................... 42 B PERMEABILITY TRIAL DATA..........................................................................................43 C COMPRESSION TEST GRAPHS......................................................................................... 44 LIST OF REFERENCES...............................................................................................................50 BIOGRAPHICAL SKETCH.........................................................................................................52

PAGE 7

7 LIST OF TABLES Table page 3-1 Number 89 limestone coarse aggregate sieve analysis...................................................... 19 3-2 Specific gravity and percent absorption of 89 limestone coarse aggregate....................... 20 3-3 Unit weight and voids content of 89 limestone coarse aggregate...................................... 20 3-4 Physical and chemical propert ies of Portland cement type II............................................ 21 3-5 Physical and chemical propertie s of granulated blast furnace slag.................................... 21 3-6 Physical and chem ical pr operties of type f fly ash............................................................21 3-7 Prelim inary pervious concrete mix designs using Portland ceme nt.................................. 22 3-8 Final pervious concrete mix designs.................................................................................. 22 3-9 Example of mixture proportioning usi ng data from mix design numb er 4........................ 23 3-10 Pervious concrete specimen labeling system..................................................................... 25 3-11 Miracle-Gro LiquaFeed Plant Food chemical composition by weight........................ 30 3-12 Hi-Yield Nitrate of Soda chemi cal composition by weight............................................. 30 4-1 Specific gravity, volume of voids, and por osity of pervious concrete specimens............. 32 4-2 Concrete sample porosity by compaction method............................................................. 33 4-3 Permeability data for pervious concrete samples by mix design and compaction method......................................................................................................................... .......34 4-4 Average hydraulic conductivity by mix design and compaction m ethod.......................... 34 4-5 Compressive strengths of pervious concrete specimens at 14 and 28 days....................... 36 4-6 Initial water compositions................................................................................................. .38 4-7 Initial stormwater effl uent composition and change..........................................................38 4-8 Stormwater effluent composition and change over time................................................... 38 B-1 Time values for permeability trials.................................................................................... 43

PAGE 8

8 LIST OF FIGURES Figure page 3-1 Mechanical sieve shak er with nested sieves...................................................................... 18 3-2 Num ber 89 limestone coarse aggregate particle size distribution curve............................19 3-2 Six-inch cylindrical mold with two-inch high collar......................................................... 24 3-3 Hydraulically loaded compre ssive strength testing m achine............................................. 29 3-4 Stormwater testing procedure............................................................................................ 31 4-1 Average permeability of each mix design by compaction method.................................... 35 4-2 Fourteen-day compressive strength of pe rvious concrete specimens organized by mix design and com paction method.......................................................................................... 36 4-3 Stormwater effluent properties ove r time for samples B, E, H, and K.............................. 39 A-1 Concrete specimens by mix design and compaction method ............................................42 C-1 Sample A compressive strength test.................................................................................. 44 C-2 Sample B compressive strength test.................................................................................. 44 C-3 Sample C compressive strength test.................................................................................. 45 C-4 Sample D compressive strength test.................................................................................. 45 C-5 Sample E compressive strength test................................................................................... 46 C-6 Sample F compressive strength test................................................................................... 46 C-7 Sample G compressive strength test.................................................................................. 47 C-8 Sample H compressive strength test.................................................................................. 47 C-9 Sample I compressive strength test.................................................................................... 48 C-10 Sample J compressive strength test.................................................................................... 48 C-11 Sample K compressive strength test.................................................................................. 49

PAGE 9

9 LIST OF OBJECTS Object page 3-1 Video of permeability test using falli ng head permeameter (.m file MB)............. 28

PAGE 10

10 LIST OF ABBREVIATIONS A/C Aggregate to Ceme nt Ratio APHA American Public Health Association ASTM American Society for Testing and Materials BMP Best Management Practice BFS Blast Furnace Slag CS Compressive Strength FA Fly Ash FM Fineness Modulus LOI Loss on Ignition P Porosity PC Portland Cement PR Percolation Rate PVC Polyvinyl Chloride SG Specific Gravity Vv Volume of Voids W/C Water to Cement Ratio

PAGE 11

11 Abstract of Thesis Presen ted to the Graduate School of the University of Florida in Partial Fulfillment of the Requirements for the Degree of Master of Science in Building Construction STORMWATER FILTRATION PROPERTIES OF PERVIOUS CONCRETE By Sarah Mace Farmerie August 2009 Chair: Larry Muszynski Cochair: R. Raymond Issa Major: Building Construction Stormwater runoff is a major source of concern as the percent of impervious surfaces covering the planet continues to rise because it causes physica lly and ecologically detrimental changes to nearby surface waterways. The Un ited States Environmental Protection Agency offers a number of best manageme nt practices (BMP) to better c ontrol the effects of this runoff on the environment. Pervious concrete is cons idered a BMP for its ability to reduce the total volume of stormwater runoff. The purpose of this research was to examine the stormwater filtration abilities of pervious concrete made with limestone pea gravel (#89) and a variety of cementitious materials: Portland cement, granulated blast furnace slag, and fly ash. Using tests for porosity, permeability, and compressive strength on the concrete specimens, as well as data obtained about the physical properties of the st ormwater before and after filtration by the concrete, it was concluded that pervious concrete made with mineral admixtures does effectively minimize the amount of pollutants found in the st ormwater effluent. When the contaminated stormwater was allowed three days of contact wi th the pervious concrete specimens, there were significant reductions in the levels of nitrat es and phosphates found in the stormwater. The dissolved oxygen levels increased with time, a nother indication of the beneficial effects of pervious concrete on stormwater runoff.

PAGE 12

12 CHAPTER 1 INTRODUCTION Stormwater is the water cr eated during any rainfa ll even t that runs over impervious surfaces and is often discharged into nearby wate rways, either directly or through a conveyance system. It has many detrimental effects on the environment, of which it is known to create the following problems for nearby surface waterways: Pollution from physical and chemical contaminants Physically and ecologically damaging change s in flow rate and total runoff volume To address these issues, this research examined the ability of pervious concrete made with different cementitious materials and compacted through vibration, Proctor hammering, or rodding to filter out common pollutants found in st ormwater runoff. Some questions posed by this research were: What effects on permeability and compressive strength are caused by the different compaction methods used in this research? What are the effects of different compaction methods (vibration, proctoring, rodding) on the ability of pervious concrete to filter stormwater pollutants? What effects do different cementitious materials (Portland cement, blast furnace slag, fly ash) have on the filtration abilities of pervious concrete?

PAGE 13

13 CHAPTER 2 LITERATURE REVIEW The literature review is divided into three se ctions: storm water runoff, alternative water filtration methods, and pervious concrete as a best management practice (BMP). It is essential to understand the composition of stormwater and how it negatively affects the environment before beginning to explore solutions to those problems. Other water filtration systems are also covered to better assess the characteristic s of pervious concrete that may be able to affect the composition of stormwater effluent. The United States Environmental Prot ection Agency (EPA) has a list of over 275 BMP for stormwater and pervi ous concrete is one of them. Stormwater Runoff In Polluted Urban Runoff: A Source of Con cern, The University of Wisconsin-Extension and the W isconsin Department of Natural Re sources break down the common pollutants found in stormwater runoff. The contaminants ar e listed as nutrients, oxygen demanding material, bacteria, toxic pollutants, metals, pesticides, a nd other chemicals. Of the nutrients found in stormwater, phosphorous is one of the most detrimental because it promotes weed and algae growth in the waterways that serve as recipients of stormwater. Nitrogen is another nutrient of concern. Oxygen demanding materials, such as pe t and agricultural waste, can totally deplete a water supply of its oxygen supply, causing stress or death to fish and other wildlife found in waterways. Bacteria levels, sp ecifically of fecal coliform bacteria, are much higher in urban runoff than the levels considered safe for swimming, causing public health problems for the recipient waterways. Toxic pollutants in the form of metals, pesticides, polychlorinated biphenyls (PCBs) and polycyclic aromatic hydrocarbons (PAHs) are of the greatest concern to stormwater managers because of the special challenges that their control pose. These toxic

PAGE 14

14 substances are known to have the ab ility to cause birth defects, dis ease, or even death (University of Wisconsin-Extension and Wisconsin De partment of Natural Resources 1997). Alternative Water Management Systems Slow sand filters, which have characteris tics similar to pervious concrete, are the primary subjects of the article Water Purification Us ing Sand. R.S. Wotton describes the water purification process in slow sand filters and likens the process to the natural water filtration found in sand banks and sandy beaches. Wotton exam ines the biology of these slow sand filters for making fresh water safe for drinking by re moving any impurities, including pathogenic organisms and chemicals. Slow sand filters are usually housed in a concrete tank with drains along the bottom. The bottom of the tank is then lined with porous bricks, which are covered with pre-treated sand. Water broug ht into the tank must first be treated with chemicals, ozone, centrifugation, or filtration to remove smaller partic les and some dissolved matter. It then filters through the sand and porous bric k layers, becoming purified in the process (Wotton 2002). Pervious Concrete as a Best Management Practice Pervious concrete can reduce road spray and hydroplaning, while also mi nimizing water pollution from noxious substances found in the effl uent of storm water. A concrete with zero slump and no fines, it can be modified with varying compositions of Portland cement, coarse aggregate, water, and admixtures The concretes void structure of 20 to 25 percent allows water to flow quickly through the materi al without creating runoff. It is likened to a cement-treated permeable base, which allows for passive wate r treatment of storm water by allowing for the absorption of the water into adjacent soils. Allo wing water to filter through soils in this way gives bacteria and other microbes the chance to decompose pollutants before they reach groundwater stores or nearby surface waters. This water eventually reaches groundwater aquifers sans pollutants (NRMCA 2008). The Environmental Protection Agency (EPA)

PAGE 15

15 recommends the use of pervious pavement as a best management practice (BMP) for stormwater control because of its ability to allow rainwater to filter through the paved surface into the soil below, thereby reducing runoff. The underlying site conditions, such as su bsoil permeability and porosity, ground water conditions, depth of water tabl e, and grade of slope must also be properly evaluated for successful applic ation. For proper drainage and pollutant removal, it is recommended that the following be used: a soil with perm eability rated to at least 0.5 in./hr. (1.3 cm./hr) and a minimum of 4 ft. (1.2 m.) of clear ance between the pavement and bedrock or water table. To maintain the permeability of the pavement, the EPA also recommends quarterly maintenance by vacuum sweeping and high-pressure washing (EPA 1999). In a study on pervious concrete and its ability to filter the effluent from cow manure, Joe Luck and his fellow researchers investigated the use of pervious concrete in agricultural settings to separate solid and liquid draina ge from animal feeding pads, manure, or compost storage pads. The research team created pervious concrete sa mples using two different aggregates, limestone and river gravel, each in two different sizes. They also played with admixtures, fiber, and fly ash additives so that they ended up with 16 unique concrete samples. The researchers tested the samples by piling composted beef cattle manure a nd bedding on top of each of the samples, as well as on top of an 80-grade wire mesh screen. They then poured water over top of each of the samples, and tested the water that had filtrat ed through each sample for concentrations of pollutants. The researchers determined that the pervious concrete filtration method greatly reduced the total amount of nitrogen, soluble phosphorus, and phos phorus in the effluent from the concrete samples, but that the filtration thr ough pervious concrete di d not affect levels of dissolved organic carbon, ammonium, nitr ate, and nitrite (Luck et al. 2008).

PAGE 16

16 Another study performed by researchers at the University of Kentucky introduced plans to test the use of pervious concrete as a flooring material in horse handling areas. The goal of the new flooring design was to prot ect ground and surface waters from contamination, while taking into account the safety of the horse and its ha ndler. The floor design consisted of a 5.5-inch pervious concrete pad on top of 8 inches of #57 or larger gravel, on top of 6 inches of #2 stone, which creates a large storage area for water to slowly drain into the ground. The researchers believed that the water quality of the runoff would be improved by filtering through pervious concrete because the concrete provides a habitat fo r beneficial bacteria to thrive. The bacteria are capable of destroying harmful pathogens f ound in the livestock runoff. The limitations of this design idea include the likelihood that, over ti me, organic material will clog the pores of the pervious pavement (H iggins et al. 2007).

PAGE 17

17 CHAPTER 3 MATERIALS AND METHODOLOGY This chapter begins with the char acterization of the aggregate and cementitious materials used in this research. It then details the methods used to fabri cate the pervious concrete samples and to test them according to American Societ y for Testing and Materials (ASTM) standard specifications. Finally, the materials and procedur es used to determine how effectively pervious concrete filters stormwater are explained. Materials Coarse Aggregate For the purpose of allowing stormw ater th e maximum amount of surface contact as it flows through the pervious concre te, the concrete samples were designed to have low porosity. To do so, number 89 limestone was selected as the coarse aggregate. Number 89 limestone is a combination of material sizes 8 and 9. Accord ing to ASTM Standard C33, number 89 aggregate should fall between the 3/8-inch and number 16 sieves (9.5 to 1.18 mm.). The physical properties of the 89 limestone were obtained through the following standard procedures: ASTM C136: Sieve Analysis of Coarse Aggregate, AS TM C29: Unit Weight and Voids in Concrete, ASTM C127: Specific Gravity and Abso rption of Coarse Aggregate. ASTM C136: Sieve Analysis of Coarse Aggregate. This standard procedure was used to create a particle size distribut ion of the coarse aggregate by sieving the material through gradually smaller sieve sizes. Using a mechanical sieve shaker and a nesting of seven sieves (3/8-in. through #100), an oven-dried sample of the 89 limestone weighing 1050 g. (2.315 lb.) was separated into its component parts. The si eves shook for 10 minutes before determining the amount of aggregate retained on each sieve. Th e shaking apparatus is shown in Figure 3-1. The results of this standard method are given in Table 3-1 and Figure 3-2. Table 3-1 gives the

PAGE 18

18 percent of aggregate retained a nd passing each sieve, which is important for determining whether the aggregate meets ASTM C33 specifications. Th e fineness modulus (FM) given in Table 3-1 is calculated using Equation 3-1. The larger the fineness modulus, the coarser the aggregate is. Figure 3-2 shows the graph of the percent passing each sieve. The data from the sieve analysis indicate that the per cent passing the number 4 sieve was above the high boundary given in the ASTM specifications, and the pe rcent passing the number 8 sieve was below the low boundary. Therefore, the 89 limestone coarse aggreg ate did not meet ASTM C33 specifications. Cumulative Percent Retained on Sieves 4, 8, 16, 30, 50, 100 FM = 100 (3-1) Figure 3-1. Mechanical sieve sh aker with nested sieves

PAGE 19

19 Table 3-1. Number 89 limestone coarse aggregate sieve analysis Sieve # Mass of Each Sieve (g) Mass of each sieve + retained Aggregate (g) Mass of Retained Aggregate (g) Percent Retained on Sieve Cumulative Percent Retained Percent Passing Sieve ASTM C33 Low Percent Passing ASTM C33 High Percent Passing 3/8 in 765 766 1 0.10 0.10 99.90 90 100 #4 590 976 386 36.76 36.86 63.14 20 55 #8 578 1200 622 59.24 96.10 3.90 5 30 #16 425 451 26 2.48 98.57 1.43 0 10 #30 305 307 2 0.19 98.76 1.24 #50 279 280 1 0.10 98.86 1.14 0 5 #100 261 262 1 0.10 98.95 1.05 Pan 518 530 12 1.14 100.10 FM: 5.28 Total 3721 4772 1051 100 Figure 3-2. Number 89 limestone coarse ag gregate particle size distribution curve ASTM C127: Specific Gravity and Absorption of Coarse Aggregate. This standard procedure was followed to determine the specif ic gravity and absorption of the 89 limestone aggregate. The specific gravity is expressed in terms of the bulk specific gravity, the saturatedsurface-dried (SSD) bulk specific gravity, and the a pparent specific gravity. The specific gravity

PAGE 20

20 represents the weight of the aggregate compared to the weight of an equal volume of water. The procedure was performed twice, a nd the results averaged. The results of both trials are shown in Table 3-2. The data obtained for all three measur es of specific gravity fall within the commonly accepted values for limestone (2.1-2.86). Table 3-2. Specific gravity and percent abso rption of 89 limestone coarse aggregate Trial 1 Trial 2 Average Weight of oven-dried test sample in air (g) 2817 1164 Weight of saturated-surface-dry (SSD) sample in air (g) 2935 1265 Weight of saturated sample in water (g) 1834 693.7 Bulk specific gravity 2.50 2.04 2.27 SSD bulk specific gravity 2.66 2.21 2.435 Apparent specific gravity 2.86 2.48 2.67 Absorption (%) 4.18 8.68 6.43 ASTM C29: Unit Weight and Voids in Aggregate. This standard procedure was used to calculate the loose unit weight, co mpact unit weight, and void cont ent of the 89 limestone coarse aggregate. To calculate the void content, the average value for the bul k specific gravity (2.27) and the compact unit weight (86.3 lb.) were us ed. Table 3-3 gives the data for each test performed. The results from these tests helped to determine the mix design proportions for the pervious concrete samples us ed in this research. Table 3-3. Unit weight and voids content of 89 limestone coarse aggregate Loose unit weight (lb) 80.8 Compact unit weight (lb) 86.3 Void content (%) 38.9 Cementitious Materials Properties for each of the cementitious m aterials used to make the concrete samples were obtained from the manufacturers. These attributes are given in Tables 3-4, 3-5, and 3-6. Granulated blast furnace slag (sla g) and fly ash were chosen as a dditives to some of the concrete

PAGE 21

21 mixes because of their ability to partially replace the amount of Portland cement used. These additives are known to add streng th and durability to concrete. Table 3-4. Physical and chemical pr operties of Portland cement type II Setting Time (min) Compressive Strength (N/mm2) Blaine (cm2/g) Initial Final 3 days 7 days Al2O3 Fe2O3 MgO SO3 LOI 2800 45 375 1450 2470 6.0 6.0 6.0 3.0 3.0 Table 3-5. Physical and chemical propert ies of granulated blast furnace slag Specific gravity Blaine (m2/kg) Air content S SO3 2.95 501 3.9 1.04 2.6 Table 3-6. Physical and chemical properties of type f fly ash Specific gravity LOI Moisture content SiO2 Al2O3 Fe2O3 CaO MgO Na2O SO3 K2O 2.18 2.32 0.07 57.87 26.79 4.45 2.44 0.94 0.54 0.28 2.41 Design, Fabrication, and Curing of Pervious Concrete Specimens This section covers the devel opment of four pervious concre te mix designs, as well as the m ixing, pouring, compaction, and curing of 24 pervious concrete samples. In the mix design section, the preliminary and final mix proporti ons are discussed. The compaction section explains the three different compacti on methods used in this research. Mix Design Proportioning Using the data obtained for the 89 limest one coarse aggregate and for the three cementitious materials, five preliminary pervious concrete mixes were fabricated and examined for porosity and proper proportioning These five mix designs ar e given in Table 3-7. After completing the preliminary samples, a mix design for each of the four concrete mixes was finalized. The final mix designs are shown in Table 3-8. Six specimens were created for each mix design. The major difference between the mi xes is the cementitious material used. The cementitious material combinations are broken down below:

PAGE 22

22 Mix 1: Portland cement Mix 2: Portland cement and granulated blast furnace slag Mix 3: Portland cement and fly ash Mix 4: Portland cement, granulated blast furnace slag, and fly ash Table 3-7. Preliminary pervious concrete mix designs using Portland cement Preliminary test number Aggregate to cement ratio Water to cement ratio 1 4.50 0.47 2 4.50 0.46 3 4.83 0.35 4 4.50 0.30 5 4.00 0.30 Table 3-8. Final pervious concrete mix designs Mix number Portland cement (%) Blast furnace slag (%) Fly ash (%) Aggregate / cement Water / cement 1 100 4.5 0.300 2 50 50 4.5 0.296 3 80 20 4.5 0.270 4 40 40 20 4.5 0.290 Mixing and Pouring Concrete Samples Using the proportions given in Table 3-8, the final pervious concrete specimens were mixed and poured acco rding to the following procedur e that results in six (6 in. x 6 in.) test cylinders per mix: Saturate 89 limestone coarse aggregate overni ght with clean, municipa lly available water. Surface dry the saturated aggregate by rolling in cloth towels, th en weigh out 65 70 lb. of the saturated-surface-dry (SSD) aggregate. Divide the weight of the SSD aggregate by 4.5 to determine the necessary weight of cementitious material. Multiply this weight by the desire d proportion of a given cementitious material. Collect the desired weight for each material. Multiply the total weight of cementitious material by the water to cement ratio to determine the weight of water needed for the mix. An exam ple of this process is given in Table 3-9, which uses values from sample set number four. Once the aggregate, cementitious materials, and water have been weighed to design specifications, the mixing process can begin.

PAGE 23

23 Wet the cement mixer and empty any excess water. Add all of the aggreg ate and half of the water to the mixer. Run the mixer just long enough to wet all of the aggregate, about 30 seconds. Then, add all of the cementitious material and mix for 1 2 minutes. Finally, add the remaining water and mix for 3 5 minut es, being sure to scra pe off any material stuck to the sides of the mixer and put it back into the concrete mix. Mix until concrete appears shiny and material begins to hold toge ther when formed into a palm-sized ball. Let the concrete sit in the mi xer for another 2 minutes. Prepare six (6 in. x 6 in.) wax-coated cardboard cylinders for the concrete samples. Place concrete in the six cylinders and follow the compaction methods explained in the section below. Table 3-9. Example of mixture proportioni ng using data from mix design number 4 Cementitious material (aggregate weight / 4.5) = 15.00 lb. Aggregate Portland cement (cementitious weight 0.4) Blast furnace slag (cementitious weight 0.4) Fly ash (cementitious weight 0.2) Water (total cementitious weight 0.29) Weight (lb.) 67.53 6 6 3 4.35 Compaction Methods Currently, there are no standard methods for compacting pervious concrete sam ples in a laboratory setting so the compaction methods used in this research ar e variations on methods used in the field on pervious c oncrete, or in the la boratory on soils and co nventional concrete. Each of the 24 pervious concre te test samples was compacted according to one of the following three methods: vibration, proctoring, or rodding. To facilitate the compaction process, each cylindrical mold was fitted with a 2-inch high co llar on the top rim prior to placing any concrete in the mold. This apparatus is shown in Fi gure 3-2. The compaction methods are described below. Vibration. The vibration compaction method is a modified version of the standard process of vibrating conventional concrete sa mples found in ASTM C192: Standard for Making and Curing Concrete Test Specimens in the Labo ratory. To perform this compaction method, the pervious concrete mix was placed in the cylindr ical mold until it was filled to the top of the

PAGE 24

24 collar. The specimens were then placed on a 75 Hz. vibrating table with an 18.87 lb. weight (6 in. x 2 in. steel cylinder) resti ng on top of the concrete. The specimens were vibrated for 10 seconds. The collar was then removed a nd any excess concrete screed off the top. Figure 3-2. Six-inch cylindrical mo ld with two-inch high collar Proctoring. The proctor method of compaction borrowed aspects of the standard procedures in ASTM D698: Standard Test Meth od for Laboratory Compaction Characteristics of Soil Using Standard Effort. To perform this compaction procedure, the cylinders were filled with the concrete mix to the top of the collar. The cylindrical 18.87 lb. steel weight was placed on top of the concrete, which then received 75 blows from a 5.5 lb. hammer dropped from a height of 12 inches, producing a co mpaction effort of 12,400 ft.-lb.f./ft.3 (600 kN.-m./m.3). After compaction, the collar was removed and excess concrete screed off the top. Rodding. The rodding procedure followed the standard compaction procedure found in ASTM C192: Standard for Making and Curing Concre te Test Specimens in the Laboratory. The concrete was placed in the mold in three laye rs and each layer was compacted 25 times using a 3/8-in. diameter rod. When th e third layer was compacted, the collar was removed and the excess material screed off to create a level surface on the mold.

PAGE 25

25 Curing Process Each of the pervious concrete samples was allo we d to cure in air for the first 24 3 hours after compaction. The cardboard forms were then stripped from the samples and the samples were submerged in a saturated limewater soluti on. The specimens were allowed to cure for 12 days before being removed, drie d, labeled, and sulfur capped for compressive strength tests on the fourteenth day after fabric ation. The labeling system is described in Table 3-10. Two samples were made for each of the 12 differe nt mix-compaction combinations, resulting in a total of 24 specimens. Table 3-10. Pervious concrete specimen labeling system Cementitious material Compaction method Portland cement Portland cement + blast furnace slag Portland cement + fly ash Portland cement + blast furnace slag + fly ash Vibration A D G J Proctoring B E H K Rodding C F I L Hardened Concrete Testing On the thirteenth day after fabric ation, the specimens were removed from the limewater tank and allowed to dry before conducting the following tests: sp ecific gravity (SG), volume of voids (Vv), porosity (P), permeability, and compre ssive strength (CS). These tests help to characterize the effects of each mix design and compaction method. The results of these tests will be used to better understand the relationship between a samples characteristics and its water filtration capacity. Specific Gravity, Volume of Voids, and Porosity To test the concrete cylinders for specifi c gravity, volume of voids, and porosity, the samples were allowed to dry in the sun for 24 6 hours before beginning the procedure. Then, the m ass of each sample (Ms) was determined by weighing the dry samples in air in grams. The

PAGE 26

26 total volume (Vt) of each cylinder is assumed to be about 2780 cm.3 (169.65 in.3) because all samples were poured into 6 in. x 6 in. cylindrical molds. To determine the volume of solids (Vs) of each sample, Archimedess Principle was used. The weight of water displaced by the samples was taken in grams. Because one gram of water equals one cubic centimeter of water, the weight of the water displaced by each samp le was converted to volume in cm.3. Equations 3-2, 3-3, and 3-4 were used to calculate the specific gravit y, volume of voids, and porosity of each sample. Ms Specific Gravity (SG) = Vs (3-2) Ms Volume of Voids (Vv) = Vs (3-3) Ms Porosity = Vs *100 (3-4) Permeability To test the permeability of the pervio us c oncrete specimens, a falling head permeameter (Figure 3-3) was constructed. The permeameter was designed to create a hydraulic head above the concrete sample that declines with time. Darcys Law (Equation 3-5) was used to calculate the hydraulic conductivity (in/sec) from the data obtained using the permeameter. Falling head permeameter The permeameter consists of a calibrated 6-inch diameter clear polyvinyl chloride (PVC) pi pe, 24-inches long that rests on top of the pervious concrete sample. The sample is connected to both the clear PVC pipe above and the opaque 6-inch PVC pipe below with rubber gaskets tightened by clam ps. The height of the top of the concrete sample and the bottom of the clear PVC cylinder are at equilibrium with the height of the top of the discharge pipe on the opposite side of a 3-inch PVC ball valve.

PAGE 27

27 Using the falling head permeameter. After securing the concre te sample in between the two 6-inch pipes and with the ball valve ope n, air in the system was flushed out by running municipally available water through the specimen and out the discharge pipe until equilibrium was reached at the zero-inch mark on the graduated cylinder. The valve was then closed. Water was poured into the graduated cylinder until it reach ed the 22-inch mark. To measure the flow of water through the specimen, a stopwatch was starte d when the valve was opened. Time readings were taken at 12-inch and 2-inch marks to determin e the rate of flow from 22 inches to 2 inches, and from 12 inches to 2 inches. This procedur e was then repeated two more times per sample. Object 3-1 is a video of this process. By using Darcys Law (Equation 3-5), the hydraulic conductivity, k, can be calculated. aL h0 k = At loge h1 (3-5) Where: a = Cross-sectional area of the calibrated clea r PVC cylinder L Length of the pervious concrete sample A Cross-sectional area of the pervious concrete sample t = Elapsed time from h0 to h1 h0 Initial water head height h1 Final water head height In this experiment, the cross-se ctional area of the calibrated cl ear PVC cylinder and the pervious concrete sample are the same (a = A) so Da rcys Law may be simplified to Equation 3-6. L h0 k = t loge h1 (3-6)

PAGE 28

28 By filling in the values for h0 and h1 (Part 1: h0 = 22 in, h1 = 2 in; Part 2: h0 = 12 in, h1 = 2 in), Equation 3-6 may be simplified again. The new equations (Equations 3-7 and 3-8) are given for Parts 1 and 2 below. 14.4 Part 1: k = t (3-7) 10.8 Part 2: k = t (3-8) Object 3-1. Video of permeability test using falling head permeameter (. file MB) Compressive Strength The compressive strength of each pervious conc rete sam ple was tested in accordance with ASTM C39: Standard Test Method for Compre ssive Strength of Cy lindrical Concrete Specimens. When the concrete specimens were removed from the limewater solution on the thirteenth day after fabrication, half of the samples (one each of specimens A through L) were taken to the Florida Department of Transportation (FDOT) State Materials Testing Laboratory to be sulfur-capped. The samples were picked up later in the day to be tested for compressive strength on the fourteenth day after fabrication. At 28 days from fabrication, eight of the second set of samples were tested for saturated compressive strength. The compressive strength was tested using a compressive strength machine that allowed the samples to be hydraulically loaded at a cons tant rate of 0.05 in./min. The machine is shown in Figure 3-3. In accordance with ASTM C39, the maximum compressive strength of each specimen was multiplied by a factor of 0.87 because th e standard calls for samples that are a 2:1 ratio and the 6 in. x 6 in. samples used in this research were a size ratio of 1:1.

PAGE 29

29 Figure 3-3. Hydraulically loaded co mpressive strength testing machine Stormwater Filtration and Testing Methods Each of the pervious concrete samples was te st ed for its ability to filter physical and chemical contaminants from stormwater by foll owing a series of water collection and testing methods. Prior to collecting stormwater, the EPAs websites Surf Your Watershed and STORET, EPAs largest computerized environmen tal data system were consulted for data and information about the contaminants found in th e waterways of two area watersheds: Oklawaha (U.S. Geological Survey 03080102) and Santa Fe (03110206). Based on this information, water samples were taken from Newnans Lake, Sweet water Branch, and Lake Santa Fe and then tested for contaminant levels that fe ll within the ranges of the CHEMets water testing kits used in this research. After finding it difficult to loca te stormwater with adequate contaminant levels, it became necessary to fabricate polluted stormw ater. To do so, two 13 L. water samples were taken from Lake Santa Fe a nd altered with Miracle-Gro LiquaFeed Plant Food and Hi-Yield Nitrate of Soda, the chemical compositions of which are given in Tables 3-11 and 3-12. The stormwater effluent testing procedure is broke n into two parts: initial testing and water composition change over time.

PAGE 30

30 Table 3-11. Miracle-Gro LiquaFeed Plant Food chemical composition by weight Total Nitrogen (N) Urea Nitrogen 12% 12% Available Phosphate (P2O5) 4% Soluble Potash (K2O) 8% Manganese (Mn) Chelated Manganese (Mn) 0.05% 0.05% Zinc (Zn) Chelated Zinc (Zn) 0.05% 0.05% Table 3-12. Hi-Yield Nitrate of Soda chemi cal composition by weight Total Nitrogen (N) Nitrate Nitrogen 16% 16% Initial Testing Before beginning the tests for pervious conc rete filtration properties, the fabricated stormwater and distilled water were test ed for pH, temp erature (C), nitrate (NO3, ppm.), phosphate (PO4, ppm.), and dissolved oxygen (DO, ppm.). Concrete samples A, C, D, F, G, I, J, and L were then tested for their water filtration characteristics by attaching the clear PVC pipe from the falling head permeameter to the top of each sample with a gasket and placing the sample in a five gallon bucket. Two liters of the fabricated stormwater were poured into the PVC pipe and allowed to percolate through each sa mple, which is demonstrated in Figure 3-4 below. After about 30 seconds, the stormwater effluent was tested for pH, temperature (C), nitrate (NO3, ppm.), phosphate (PO4, ppm.), and dissolved oxygen (DO, ppm.). To test for NO3, PO4, and DO, CHEMetrics, Inc. CHEMets test kits (www.chemetrics.com) were used and the manufacturers in structions followed exactly. The NO3 kit (CHEMets K-6904) follows APHA Standard Method 4500-NO3 E, ASTM D 3867-04, Nitrite-Nitrate in Water, Test Method B, and EPA Methods for Chemical Analysis of Water and Wastes, Method 353.3. The PO4 kit (CHEMets K-8510) follows APHA Standard Method 4500-P D, while the DO kit (CHEMets K-7512) follows ASTM D 888-87, Dissolved Oxygen in Water, Test Method A. The pH was

PAGE 31

31 measured with colorpHast non-bleeding pH-indicator test stri ps submerged in the stormwater effluent for 2-10 minutes, until there was no further color change. Water Composition Change Over Time To analyze the effect of pervious concrete on contaminated stormw ater over time, samples B, E, H, and K were selected for their average porosities and permeability rates to be submerged in the fabricated stormwater for a period of thr ee days. Each of samples B, E, H, and K were first tested for their effects on a control effluent by allowing distilled wate r to filter through the system and by measuring the pH, temperature (C), nitrate (NO3, ppm.), phosphate (PO4, ppm.), and dissolved oxygen (DO, ppm.), utilizing the met hods described in the initial testing section above. Then, three liters of fabricated stormwat er were poured over each sample and allowed to soak for three days. The effluent was tested for each of the five properties on the first and third days. A. B. Figure 3-4. Stormwater testing proce dure. A) concrete sample att ached to clear PVC pipe with a gasket, B) pouring fabricated stormwater over sample, effluent collecting in bottom bucket.

PAGE 32

32 CHAPTER 4 DATA ANALYSIS This chapter presents the results fo r the harden ed concrete and stormwater filtration tests. The specific gravity, volume of voids, porosity, permeability, and compressive strength of each concrete specimen are analyzed for patterns between mix designs and compaction methods. The stormwater filtration results show the initial and extended effects of stormwater filtration by pervious concrete. Hardened Concrete Test Data Specific Gravity, Volume of Voids, and Porosity The results of the tests for specific gravity, volum e of voids, and porosity of each concrete specimen are given in Table 4-1. The data for ea ch of the four mix designs indicate that mix number one made with Portland cement had the hi ghest average porosity, while mix number four made with Portland cement, blast furnace slag, and fly ash had the lowest average porosity. In Table 4-2, the results of the specific gravity, volume of voids, and porosity tests are broken down by compaction method. The data from the compac tion sets were less conc lusive. The average porosity of each compaction method is very similar to the others. Table 4-1. Specific gravity, volume of voids, a nd porosity of pervious concrete specimens Sample Vt (cm3) Ms (g) Vs (cm3) Vv (cm3) P (%) Avg. P / Mix design (%) A 2780 4764 2118 662 23.81 24.76 B 2780 4749 2143 637 22.91 C 2780 4525 2014 766 27.55 D 2780 4848 2347 433 15.58 19.88 E 2780 4751 2196 584 21.01 F 2780 4563 2139 641 23.06 G 2780 4776 2197 583 20.97 21.60 H 2780 4781 2183 597 21.47 I 2780 4681 2158 622 22.37 J 2780 4890 2272 508 18.27 19.41 K 2780 4709 2139 641 23.06 L 2780 5039 2310 470 16.91

PAGE 33

33 Table 4-2. Concrete sample porosity by compaction method Compaction method Sample Porosity (%) Av erage porosity per compaction method (%) Vibration A 23.81 19.6575 D 15.58 G 20.97 J 18.27 Proctoring B 22.91 22.1125 E 21.01 H 21.47 K 23.06 Rodding C 27.55 22.4725 F 23.06 I 22.37 L 16.91 Permeability The results of the permeability tests using the falling head perm eameter are given in Appendix A. Those values were averaged and the average time for each trial was used to calculate the hydraulic conductivity, k, in inches per second for each sample, which are shown in Table 4-3. The hydraulic conductivity for the samples ranges from 0.23 in./sec. to 0.66 in./sec. Mix design four had the lowest average permeability at 0.33 to 0.38 in./sec., while mix design one had the highest at 0.45 to 0.51 in./sec. The process of compaction by vibrating offered the least hydraulic conductivity with a range of 0.31 to 0.36 in./sec. The proctoring and rodding compaction techniques were more closely related in that the average permeability of each ranged from 0.41 to 0.47 in./sec. and 0.44 to 0.51 in./sec., respectively. Figure 4-1 shows the average permeability of each sample by mix design, according to compaction method. From the average permeability graph, it is noted that the proctor method of compaction produced the most consistent permeability rate. There were no other real trends among the mix designs and compaction methods in regard to hydraulic conductivity.

PAGE 34

34 Table 4-3. Permeability data for pervious concrete samples by mix design and compaction method 12 in -> 2 in 22 in -> 2 in A t (sec) k (in/sec) A t (sec) k (in/sec) Mix 1 A 10.75 22.4 0.48 14.39 34.5 0.42 B 10.75 26.0 0.41 14.39 39.7 0.36 C 10.75 16.9 0.64 14.39 25.7 0.56 Mix 2 D 10.75 40.4 0.27 14.39 62.0 0.23 E 10.75 21.0 0.51 14.39 32.6 0.44 F 10.75 16.3 0.66 14.39 25.0 0.58 Mix 3 G 10.75 32.1 0.33 14.39 49.2 0.29 H 10.75 24.2 0.44 14.39 37.1 0.39 I 10.75 24.5 0.44 14.39 37.5 0.38 Mix 4 J 10.75 31.0 0.35 14.39 47.1 0.31 K 10.75 21.3 0.50 14.39 33.0 0.44 L 10.75 38.8 0.28 14.39 59.7 0.24 Vibration A 10.75 22.4 0.48 14.39 34.5 0.42 D 10.75 40.4 0.27 14.39 62.0 0.23 G 10.75 32.1 0.33 14.39 49.2 0.29 J 10.75 31.0 0.35 14.39 47.1 0.31 Proctoring B 10.75 26.0 0.41 14.39 39.7 0.36 E 10.75 21.0 0.51 14.39 32.6 0.44 H 10.75 24.2 0.44 14.39 37.1 0.39 K 10.75 21.3 0.50 14.39 33.0 0.44 Rodding C 10.75 16.9 0.64 14.39 25.7 0.56 F 10.75 16.3 0.66 14.39 25.0 0.58 I 10.75 24.5 0.44 14.39 37.5 0.38 L 10.75 38.8 0.28 14.39 59.7 0.24 Table 4-4. Average hydraulic conductivit y by mix design and compaction method k (in/sec) 12 in -> 2 in 22 in -> 2 in Overall Mix 1 0.51 0.45 0.48 Mix 2 0.48 0.42 0.45 Mix 3 0.40 0.35 0.38 Mix 4 0.38 0.33 0.36 Vibration 0.36 0.31 0.34 Proctoring 0.47 0.41 0.44 Rodding 0.51 0.44 0.48

PAGE 35

35 Figure 4-1. Average permeability of each mix design by compaction method Compressive Strength One half of the 24 pervious concrete specimens were su lfur capped and tested for compressive strength at 14 days. However, sa m ple L was improperly capped the first time so it was returned to the FDOT to be repaired and was not tested for compressive strength until 28 days after fabrication. Therefore, the data obtained for the 14-day co mpressive strength of sample L was uncharacteristically high. Eight of the second set of samples were saturated and tested at 28 days using neoprene caps. Wang et al. (2009) studied the eff ect of saturation on the compressive strength of traditi onal concrete and concluded that the compressive strengths of saturated concrete samples are lower than those of dry concrete samples. The results of the compressive strength tests given in Table 4-5 su pport the theory that saturated samples have lower compressive strengths. In general, the concrete mixes that included blast furnace slag had higher compressive strengths than the other two mixes. Also notable is that each compaction method resulted in relatively consistent compressi ve strength values ac ross all mix designs. Rodded sample L is the only specimen that fall s outside of these rang es. The compressive

PAGE 36

36 strengths of each sample are given by mix de sign and compaction method in Figure 4-2, which depicts the trends mentioned above. Table 4-5. Compressive strengths of pervi ous concrete specimens at 14 and 28 days Compressive strength (psi) Satu rated compressive strength (psi) 14 days 28 days A 1044 566 B 809 C 566 604 D 1175 948 E 1192 F 966 735 G 1096 919 H 818 I 940 790 J 1166 726 K 887 L 1818* 1022 Figure 4-2. Fourteen-day compressive strength of pervious conc rete specimens organized by mix design and compaction method Stormwater Filtration Data Before filtering stormwater through the pervious concrete samples, the di stilled water, and fabricated stormwater mixes 1 a nd 2 were tested for temperature, pH, dissolved oxygen, nitrate,

PAGE 37

37 and phosphate levels. That information is given in Table 4-6. The data from the control tests were then used to assess how pe rvious concrete changes the composition of stormwater when the water percolates through its pores Samples A, B, E, H, and K were tested using the first fabricated stormwater, polluted water 1, while the remaining samples (C, D, F, G, I, J, L) were tested using polluted water 2. The composition and change of the stormwater effluent after flowing through each sample is given in Table 4-7. At the end of the ini tial testing phase, the stormwater effluent tended to increase in alkalin ity, decline in dissolved oxygen levels, and show little, if any, decline in n itrate and phosphate levels. The increase in alkalinity could be due to a few factors. The concrete samples were coated in a fine layer of lime af ter soaking in limewater solution. Limewater and the Portland cement used in each mix design are highly alkaline materials that likely had an effect on the pH of the stormwater effluent. The decline in dissolved oxygen is not necessarily desirable as dissolved o xygen levels below 3 ppm. begin to stress most warm water species of fish. The nitrate and phos phate results do not allow for any statements to be made about the nitrate and phosphate fi ltering capacity of pervious concrete. For the second phase of the stormwater filtra tion tests, samples B, E, H, and K were allowed to soak in the polluted water 1 soluti on for three days to determine the effects of pervious concrete on stormwater composition over time. The samples were tested initially and then on the third day for characte rization levels. Table 4-8 gives the composition and change of the distilled water and stormwat er effluents on days one and th ree after flowing through each concrete sample. The composition data for day one follow the same patterns as described in the discussion of the first phase of results: primar ily more alkaline, and a decline in dissolved oxygen and phosphate levels. The data for the da y three compositions are much different. The pH of the stormwater was still 9.5 for every sample, but there were dramatic changes in

PAGE 38

38 dissolved oxygen, nitrate, and phosphate levels The dissolved oxygen levels rose, and the nitrate and phosphate levels de creased by significant levels. Almost all of the phosphate was removed from the stormwater effluent by the third day. The nitrate levels declined by nearly 50 percent. These results are shown graphically in Figure 4-3. The da ta indicate a decline in nitrate and phosphate levels, as well as an incr ease in dissolved oxygen over time. Table 4-6. Initial water compositions Temp. (C) pH DO (ppm) NO3 (ppm) PO4 (ppm) Distilled water 26 6.5 6 0 0 Polluted water 1 30 6.5 7 3 6 Polluted water 2 29 6.5 7 2 5 Table 4-7. Initial stormwater e ffluent composition and change Temp. (C) pH pH DO (ppm) DO NO3 (ppm) NO3 PO4 (ppm) PO4 Polluted water 1 30 6.5 7 3 6 A 30 9.5 +3 6 -1 3 0 6 0 B 28 9.5 +3 6 -1 3 0 6 0 E 24 9.5 +3 6 -1 3 0 5 -1 H 26 9.5 +3 8 +1 3 0 5 -1 K 26 9.5 +3 7 0 3 0 5 -1 Polluted water 2 29 6.5 7 2 5 C 28 9.5 +3 8 +1 1.75 -0.25 4 -1 D 29 9.5 +3 6 -1 1.75 -0.25 5 0 F 29 9.5 +3 7 0 1.75 -0.25 4 -1 G 29 9.5 +3 6 -1 1.5 -0.5 4.5 -0.5 I 29 9.5 +3 7 0 1.75 -0.25 5 0 J 29 9.5 +3 6 -1 1.25 -0.75 4 -1 L 29 9.5 +3 6 -1 1.75 -0.25 5 0 Table 4-8. Stormwater effluent composition and change over time Sample B Sample E Sample H Sample K Distilled water effluent Temperature (C) 28 26 27 28 pH 10 10 10 10 pH +3.5 +3.5 +3.5 +3.5 DO (ppm) 6 6 8 8 DO 0 0 +1 +1 NO3 (ppm) 0 0 0 0 NO3 0 0 0 0

PAGE 39

39 Table 4-8. Continued PO4 (ppm) 0 0 0 0 PO4 0 0 0 0 Day 1: Polluted water effluent Temperature (C) 28 24 26 26 pH 9.5 9.5 9.5 9.5 pH +3 +3 +3 +3 DO (ppm) 6 6 8 7 DO -1 -1 +1 0 NO3 (ppm) 3 3 3 3 NO3 0 0 0 0 PO4 (ppm) 6 5 5 5 PO4 0 -1 -1 -1 Day 3: Polluted water effluent Temperature (C) 20 20 20 20 pH 9.5 9.5 9.5 9.5 pH +3 +3 +3 +3 DO (ppm) 11 7 12 6 DO +4 0 +5 -1 NO3 (ppm) 1.75 1.25 1.75 1.75 NO3 -1.25 -1.75 -1.25 -1.25 PO4 (ppm) 0.2 0.2 0.8 0.8 PO4 -5.8 -5.8 -5.2 -5.2 Figure 4-3. Stormwater efflue nt properties over time for samples B, E, H, and K

PAGE 40

40 CHAPTER 5 CONCLUSIONS AND RECOMMENDATIONS Conclusions After examining the data presented in the hard ened concrete and stor mw ater filtration test sections above, some conclusions can be ma de about the relationships between compaction methods, permeability, and compressive strength of th e pervious concrete specimens. In regard to permeability, only the procto r method of compaction offered consistent hydraulic conductivity rates for each mix design. Th e concrete specimens that were compacted through vibration tended to have the lowest permeability and the highest compressive strength at 14 days after fabrication. Compaction by proc toring and rodding also produced consistent compressive strength results across mix designs, with roddi ng creating the lowest compressive strength results. Overall, it is likely that the pervi ous concrete specimens co mpacted by vibration would serve as the best stormwater filters due to their low porosity and hi gh compressive strength. The initial stormwater filtration tests did not produce results th at allowed for any conclusions to be made about the relationship between compaction methods and filtration ability. The ongoing filtration tests that examined only those specimens compacted by proctor hammer did give contaminant data that were consistent enough to conclude that pervious concrete is an effective method of reducing nitrate and phosphate levels in stormwater runoff. Dissolved oxygen levels in the effluent incr eased after contact with the pervious concrete for three days. The contaminant levels were consistent between the four mix designs so no conclusions could be drawn about the effect of mineral admixtures on the filtration abil ity of pervious concrete. The test results of the stormwater fi ltration procedure suggest that pervious concre te has the potential to positively affect the chemical composition of st ormwater released from the pervious concrete system.

PAGE 41

41 Recommendations As this research ind icates, there is reason to believe that pervious concrete does affect contaminant levels in stormwater runoff. It is recommended that th e following methods be explored in further research on the stormwater filtration properties of pervious concrete: Try a variety of other aggregate sources and sizes to determine if aggregate differences affect the composition of stormwater effluent. Expand the water testing parameters to include other common stormwater contaminants. Utilize more reliable test methods for determin ing the concentration of a given water quality measure. Consult with or use the serv ices of a water management laboratory. Increase the number of concrete specimens ma de for each mix/compaction method to at least three to better test for consistency among specimens. Use cores from field-poured and compacted pervious concrete because field methods are difficult to replicate in the laboratory.

PAGE 42

42 APPENDIX A PERVIOUS CONCRETE TEST SPECIMENS The pervious concrete specimens A through L are shown in Figure A-1 below. The photographs depict the bottom of eac h sample to show the effect of the compaction methods on the porosity. The photos are arranged by mix design, running from the top to the bottom of the page, and by compaction method, from left to right. From left to right, the compaction methods are: vibration, proctoring, and rodding. Figure A-1. Concrete specimens by mix design and compaction method

PAGE 43

43 APPENDIX B PERMEABILITY TRIAL DATA To test the permeability of each concrete sp ecimen, three trials were run per sample. Time values were recorded for the water to fall from 22 in. to 2 in., and from 12 in. to 2 in. during each trial. The permeability test values for each of the three trials per concrete specimen are given in Table B-1. The average time values were used in the calculation of the hydraulic conductivity, k, in Tables 4-3 and 4-4. Table B-1. Time values for permeability trials 1st Trial (sec.) 2nd Trial (sec.) 3rd Trial (sec.) Average (sec.) 12 in -> 2 in 22 in -> 2 in 12 in -> 2 in 22 in -> 2 in 12 in -> 2 in 22 in -> 2 in 12 in -> 2 in 22 in -> 2 in A 22.4 34.6 22.4 34.5 22.3 34.5 22.4 34.5 B 25.4 39.0 26.2 39.7 26.5 40.3 26.0 39.7 C 16.8 25.6 17.0 25.8 16.8 25.7 16.9 25.7 D 40.9 62.5 40.1 61.7 40.2 61.8 40.4 62.0 E 21.2 32.9 21.0 32.2 20.9 32.6 21.0 32.6 F 16.5 25.1 16.3 25.0 16.2 24.9 16.3 25.0 G 32.2 49.4 32.1 49.2 31.9 49.1 32.1 49.2 H 24.1 36.8 24.2 37.0 24.4 37.5 24.2 37.1 I 24.7 37.4 24.5 37.4 24.4 37.6 24.5 37.5 J 31.3 47.2 30.9 47.0 30.8 47.0 31.0 47.1 K 21.6 33.2 21.2 32.7 21.2 33.0 21.3 33.0 L 38.7 59.5 38.8 59.7 38.9 59.8 38.8 59.7

PAGE 44

44 APPENDIX C COMPRESSION TEST GRAPHS Included in this section are the compression te st graphs created by the hydraulic testing machine as each sample was being crushed at a ra te of 0.05 in/min. The graphs plot the stress (psi) versus time (sec). Figure C-1. Sample A comp ressive strength test Figure C-2. Sample B comp ressive strength test

PAGE 45

45 Figure C-3. Sample C comp ressive strength test Figure C-4. Sample D comp ressive strength test

PAGE 46

46 Figure C-5. Sample E comp ressive strength test Figure C-6. Sample F comp ressive strength test

PAGE 47

47 Figure C-7. Sample G comp ressive strength test Figure C-8. Sample H comp ressive strength test

PAGE 48

48 Figure C-9. Sample I compressive strength test Figure C-10. Sample J co mpressive strength test

PAGE 49

49 Figure C-11. Sample K comp ressive strength test

PAGE 50

50 LIST OF REFERENCES Dierkes, C., Holte, A., and Geiger, W.F. ( 2007). Heavy Metal Retention with a Porous Pavement Structure. Final Report of the Ready Mix Concrete Research and Education Foundation Silver Springs, Md., (Nov. 12, 2008). Higgins, S., Workman, S., and Coleman, R.J. (2007) Pervious Concrete as a Flooring Material for Horse Handling Areas. University of Kentucky Cooperative Extension Service. HydroDynamics, Inc. (2007). Sediment Loading. Erosion and Sediment Control Designer and Reviewer Manual Tallahassee, Fl., 3-4. Kosmatka, S.H., Kerkhoff, B., and Panarese, W. (2008). Design and Control of Concrete Mixtures Portland Cement Association, Skokie, Ill. Luck, J.D., Workman, S.R., Coyne, M.S., and Higgi ns, S.F. (2008). Solid Material Retention and Nutrient Reduction Properties of Pervious Concrete Mixtures. Biosys. Eng., 100, 401408. Majersky, G.M. (2008). Filtration a nd life span analysis of a pervious concrete filter. MS thesis, University of Colorado Denver, Denver, Co. National Ready Mix Concrete Association (NRMCA ). (2008). Pervious Concrete Pavement for Green, Sustainable Porous & Perm eable Stormwater Drainage. (Sept. 13, 2008). National Research Council (NRC). (2008). Urban Stormwater Management in the United States The National Academies Press, Washington, D.C. Park, S.B., Mang, T. (2004). An Experimental Study on the Water-Purific ation Properties of Porous Concrete. Cement and Concrete Research 34, 177-184. Stormwater Management Academy, University of Central Florida (UCF). (2007). Public education programming guidance manuals. How to Implement a Volunteer Water Quality Program (Apr. 15, 2009). University of Wisconsin-Extension and Wiscons in Department of Natural Resources. (1997). Polluted Urban Runoff: A source of concern (Apr. 15, 2009). United States Environmental Protection Agency (EPA). (2009A). Surf Your Watershed. (Apr. 29, 2009). United States Environmental Protection Agency (EPA). (2009B). STORET, EPAs largest computerized environmental data system. < http://www.epa.gov/storet/> (June 27, 2009).

PAGE 51

51 United States Environmental Protection Agency (EPA) (1999). Porous Pavement. EPA 832-F99-023: Storm Water Technology Fact Sheet. Wang, H., Jin, W., and Li, Q. (2009). Satura tion Effect of Dynamic and Tensile and Compressive Strength of Concrete. Advances in Structural Engineering 12(2), 279-286. Wotton, R.S. (2002). Water Purification Using Sand. Hydrobiologia, 469, 193-201.

PAGE 52

52 BIOGRAPHICAL SKETCH Sarah Mace Farmerie was born in An n Ar bor, Michigan to Jennie Mace and William Farmerie. After a move to Durham, North Carolina, Sarahs family settled in Ocala, Florida, where she graduated from high school in the International Baccalaureate Program. In 2001, Sarah began her undergraduate education at Washington University in St. Louis, where she explored engineering, arch itecture, graphic design, and Chinese. After four years in St. Louis, she earned her Bachelor of Arts in internationa l relations with a concentration in East Asian studies. In 2007, Sarah began graduate studie s in the M.E. Rinker, Sr. School of Building Construction at the University of Florida. She earned her Master of Science in Building Construction in August 2009. After graduation, she continued her studies toward a doctorate in building construction at the University of Florida.