Pervious Concrete Mix Design

Wang et al, submitted to NRMCA Concrete Technology Forum: Focus on Pervious Concrete, May 24-25, 2006, Nashville, TN

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Development of Mix Proportion for Functional and Durable Pervious Concrete

Wang, K.1, Schaefer, V. R.2, Kevern, J. T.3, and Suleiman, M.T.4

Abstract Portland cement pervious concrete (PCPC) mixes made with various types and amounts of aggregates, cementitious materials, fibers, and chemical admixtures were evaluated. Porosity, water permeability, strength, and freezing-thawing durability of the concrete were tested. The results indicated that the PCPC made with single-sized coarse aggregates generally had high permeability but not adequate strength. Addition of a small amount of fine sand (approximate 7% by weight of total aggregate) to the mixes significantly improved the concrete strength and freezing-thawing resistance while maintaining adequate water permeability. Addition of a small amount of fiber to the mixes increased the concrete strength, freezing-thawing resistance as well as void content. Based on these results, performance-based criteria are discussed for proportioning functional and durable PCPC mixes. Introduction Portland cement pervious concrete (PCPC) is increasingly used in the United States because of its various environmental benefits such as controlling storm water runoff, restoring groundwater supplies, and reducing water and soil pollution (Youngs 2005 and Kajio et al. 1998). Due to the permeability requirement, PCPC is typically designed with high void content (15-25%). Single-sized aggregate is commonly used to achieve such void content (Tennis et al. 2004). Because of the high void content, PCPC generally has low strength (800-3000 psi), which not only limits its application in cold weather regions but also is responsible for various distresses in and failures of the related structures. Lately, PCPC has been considered for some pavements in cold weather regions (such as Iowa and Minnesota). However, limited research has been conducted to characterize PCPC mix proportions and to investigate its serviceability under cold weather conditions. The present study was conducted to fill this gap and to spur PCPC applications. In this paper, PCPC mixes were designed with various types and amounts of aggregates, cementitious materials, fibers, and chemical admixtures. Porosity, water permeability, strength, and freezing-thawing (F-T) durability of the concrete samples were tested. The effects of these materials and mixture proportions on the PCPC performance/ properties were explored. The following sections describe the detailed experiments, test results, and major findings.

1 Assistant Professor, Civil, Construction, and Environmental Engineering, Iowa State University, Ames, IA,[email protected] 2 Professor, Civil, Construction, and Environmental Engineering, Iowa State University, Ames, IA, [email protected] 3 Research Assistant, Civil, Construction, and Environmental Engineering, Iowa State University, Ames, IA, [email protected] 4 Research Assistant Professor, Civil, Construction, and Environmental Engineering, Iowa State University, Ames, IA, [email protected]


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Experimental Work Materials. Type I/II cement was used in all mixes, and the cement had a fineness of 384 m2/kg and a specific gravity of 3.15. A single-sized limestone (3/8LS, which passed the (12.5 mm) sieve but retained on the 3/8 (9 mm) sieve), and two single-sized river gravels (3/8RG, which passed (12.5 mm) sieve but retained on 3/8 (9 mm) sieve, and #4RG, which passed 3/8 (9 mm) sieve but retained on No.4 (4.75 mm) sieve) were used as coarse aggregate. The properties of the coarse aggregate are summarized in Table 1, where unit weight and voids tests were performed based on ASTM C29, and the specific gravity and absorption tests were performed based on ASTM C127.

Table 1: Properties of coarse aggregates

Aggregate 3/8RG #4RG 3/8LS 3/8LS*

Unit weight (lb/ft3) 102.6 99.6 86.5 88.8

Voids (%) 37.3 38.5 43.5 44.2

Abrasion mass loss (%) 14.4 14.4 46.1 32.9

Specific gravity 2.62 2.62 2.45 2.55

Absorption 1.1 1.1 3.2 3.2 Note: 3/8LS* was from the same source but received at a different time and used for Mix 3A only

To improve concrete strength, a small amount of river sand was incorporated in the PCPC mixes. The sand had a fineness modulus of 2.9, specific gravity of 2.62, and absorption of 1.1%.

To improve the cement-aggregate bond and the F-T durability, a styrene butadiene rubber (SBR) latex was used. The SBR latex is approved by the Federal Highway Administration for latex modified concrete use in bridge deck overlays (Ramakrishnan 1992). The SBR used had a solid content of 48% and pH of 10. Various amount of polypropylene fiber is also used in selected PCPC mixes.

Air entraining agent (AEA) and high-range water reducer (HRWR) were used in the mixes that did not contain latex. The specific gravity and pH were 1.01 and 10 for the AEA (Everair plus) and 1.07 and 7.8 for the HRWR (Glenium 3400 NV), respectively. Mix Proportions. The mix design was divided into two parts. Part I was designed to investigate the effects of aggregate size and type on the void ratio and strength of pervious concrete, and Part II was to investigate the effects of sand, latex, fiber and admixtures (AEA and HRWR) on PCPC properties. All concrete mix proportions used are summarized in Table 2. The slump of the mixtures was between 0 in. to in. (0 cm and 1.27 cm ).


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Table 2: Mix proportions

Specimen Preparation. To improve the bond between cement paste and aggregate, the following mixing procedure was used:

1. A small amount of cement (


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Test Methods. In the present study, unit weight and slump tests were performed for fresh concrete based on ASTM C 138 and C143, respectively. PCPC Void ratio was tested at 7-days, compressive strength at 7, 21, and or 28 days, splitting tensile strength and water permeability at 28 days. Compressive strength tests were performed according to ASTM C39. Splitting tensile strength tests were performed based on ASTM C496.

The void content of the PCPS samples was determined by taking the difference in weight between a sample oven dry and under water and using Equation 1 (Park and Tia, 2004).

)]100(%)Vol

WW([1Vw

12r

= (1) Where: Vr = total void ratio, %; W1 = weight under water, lb (kg); W2 = oven dry weight, lb (kg); Vol. = volume of sample, ft3 (cm3); and w = density of water, lb/ft3 (kg/cm3).

Permeability of the PCPC samples was determined using the falling head permeability test apparatus illustrated in Figure 1. A sample was confined in a membrane and sealed in a rubber sleeve. Four different water heights, which represented the values that a pavement may experience, were applied to the sample, and the time for the water to drain out of the sample was then recorded. For each water height, the permeability coefficient (k) was determined using Equation 2. The average value resulting from the different water heights was defined as the permeability coefficient of the sample.

=

2

1hh

LNAtaLk (2)

Where k = coefficient of permeability, cm/s; A = cross sectional area of the standpipe, in.2 (cm2); L = length of sample, in. (cm); A = cross sectional area of specimen, in.2 (cm2); t = time in seconds from h1 to h2: h1 = initial water level, in. (cm); and h2 = finial water level, in. (cm).

Figure 1: Water permeability test setup Selected concrete mixes, with adequate void ratio and 7-day compressive strength, were further tested for freeze-thaw resistance using ASTM C666 procedure A, in which the samples were


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frozen and thawed in wet conditions. The test was completed when the sample reached 300 cycles or 15% mass loss. Mass loss was tested every 20 to 30 cycles. Results Effect of Coarse aggregate Type and Size on PCPC Properties. Table 3 presents the properties of the PCPC mixes designed in the Part I study, where different types and sizes of coarse aggregates were used in a typical PCPC mix (Table 2). As observed in Table 3, when single-sized coarse aggregate was used, the desirable void content (15%) was easily achieved. For the given mix proportion, PCPC made with river gravel had lower void content but high compressive strength than that made with limestone. For given river gravel, smaller size aggregate reduced the void content but increased 7-day compressive strength of the PCPC. However, in this group (the PCPC without sand), the highest strength was only 2500 psi (17.3 MPa ) at 28 days - the strength of the PCPC made with #4RG.

Table 3: Properties of PCPC mixes without sand (w/c=0.27, cement content 355.8 kg/m3) Compressive Strength (psi)

Mix C. Agg.

Unit Weight (lb/ft3)

Void Content

(%) 7-day 21-day 28-day

Splitting Strength

(psi)

Water Permeability

(in./sec) 1 3/8RG 116.9 28.8 1771 - - - -

2 #4RG 117.5 25.3 2100 2385 2506 287 0.10

3 3/8LS 104.1 33.6 1396 1663 1722 205 0.57 Notes: 1 kg/m3 =0.0624 lb/cf, 1 MPa=145 psi; 1 cm/sec=1417.3 inch/hour. Effect of Sand on PCPC Properties. It was observed in the Part I study that under vibration, some cement paste was accumulated at the bottom of the samples, which implied that the cement content used in the mixtures might be higher than necessary. Therefore, in the Part II study, cement content of PCPC was reduced from 600 lb/yd3 to 571 lb/yd3, while the water-to-cement ratio (w/c) was kept the same. River sand was used to replace approximate 7% (by weight) coarse aggregate in order to improve the concrete strength. Table 4 presents the properties of the PCPC mixes with the sand replacement.

Table 4: Properties of PCPC mixes with sand (w/c=0.27, cement content 338.4 kg/m3) Compressive Strength (psi)

Mix C. Agg.

Unit Weight (lb/yd3)

Void Content

(%) 7-day 21-day 28-day

Splitting Strength

(psi)

Water Permeability

(in./hr) 1A 3/8RG 130.9 20.5 3262 -- -- -- 694

2A #4RG 127.7 18.3 3299 3380 3661 421 142

3A 3/8LS 119.8 23.0 3229 -- -- -- 326 When compared with Mixes 1, 2 and 3 (Table 3), mixes 1A, 2A, and 3A (Table 4) all had significantly improved strength. Especially, the 7-day compressive strength increased from 1,390-2,100 psi (9.6-14.5 MPa) to 3,220-3,290 psi (22.2-22.7 MPa). This early-age strength improvement may have a great impact on the F-T durability of PCPC in field. It should be noted that the differences in the properties of mixes 3 and 3A might partially result from the different 3/8LS properties (see Table 1).


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Although the void content was reduced due to the introduction of fine sand in the mixtures, all void content values listed in Table 4 were still within an acceptable range (>15%) for PCPC applications. In other words, although the permeability of Mix 2A decreased from 354 in./hour to 141.7 in/hour (from 0.25 cm/sec to 0.1 cm/sec) when compared with Mix 2, this permeability value is still higher than the maximum requirement to drain the maximum 25 year-24 hour storm across the United States (i.e., 12 inch (30.5 cm) (USDA 1986). Effect of Latex on PCPC Properties. To improve the PCPC properties, approximate 10% latex solid (by weight of cement) was used into selected mixes. Due to the consideration of the material cost, the latex was used to replace the same amount of cement. As a result, the cement content of the PCPC mixes reduced from 571 lb/yd3 to 520 lb/yd3. Water-to-cement ratio (w/c) also reduced from 0.27 to 0.22 for the latex modified PCPC to reach given slump. Table 5 presents the properties of the PCPC mixes made with the sand and latex. Probably due to the less cement used, the PCPC mixes with latex (Table 5) had lower compressive strength than the mixes without latex (Table 4). However, even though less cement was used, the PCPC mixes with latex still had higher splitting tensile strength than the mixes without latex. This indicates that the addition of latex in PCPC might improve the concrete cracking resistance.

Table 5: Properties of PCPC mixes with sand and latex (w/c=0.22, cement content 308.2 kg/m3)

Compressive Strength (psi) Mix C. Agg.

Unit Weight (lb/yd3)

Void Content

(%) 7-day 21-day 28-day

Splitting Strength

(psi)

Water Permeability

(in./hour) 1B 3/8RG 127.3 20.2 2641 -- 2924 -- 340

2C #4RG 126.8 19.0 2969 3313 3349 453 255

3B 3/8LS 117.4 25.7 2483 -- -- -- 666

Table 6 presents the effect of amount of latex on PCPC properties, where latex was again used for cement replacement, rather than addition. As observed in the table, the void content of the PCPC decreased with the increased amount of latex replaced for cement. The optimal amount of latex appeared to be 10% based on the consideration of the concrete strength and permeability.

Table 6: Properties of PCPC mixes with different amount of latex (w/c=0.22)

Mix Latex Solid

(lb/yd3)

Cement Content (lb/yd3)

Unit Weight (lb/ft3)

Void Content

(%)

Compressive Strength

(psi)

Splitting Strength

(psi)

Water Permeability

(in./hour) 2D 29 542 120.3 26.0 1307 -- --

2C 52 520 126.8 19.0 2969 453 255

2E 86 485 132.2 14.1 2735 -- 57

Effect of Fiber on PCPC Properties. Table 7 presents the effect of fiber addition on PCPC properties, where Mixes 2F and 2G had no sand and Mix 2H had 7% sand for coarse aggregate replacement. Generally, addition of the fiber in PCPC slightly increased the void content and significantly increased the permeability of the concrete. More importantly, it


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improved the splitting tensile strength of concrete, which in turn enhanced the concrete F-T durability.

Table 7: Properties of PCPC mixes with fiber (w/c=0.27, cement content 308.2 kg/m3) Compressive Strength (psi)

Mix Fiber

(lb/yd3) Unit

Weight (lb/yd3)

Void Content

(%) 7-day 21-day 28-day

Splitting Strength

(psi)

Water Permeability

(in./hour) 2F .05 120.4 18.9 2587 2941 3106 348 383

2G 1.5 119.4 22.1 2601 2765 3106 358 964

2H 1.5 122.5 19.0 2988 3220 3849 353 425

F-T Durability Test Results. As mentioned before, only selected concrete mixes that had adequate void ratio and 7-day compressive strength were tested for F-T durability using ASTM C666 procedure A. Due to its high permeability, field PCPC is rarely in a saturated condition. The investigators have noted that ASTM C666 method may not appropriately simulate the field PCPC condition. However, it is believed that this simple, rapid test method simulates the extreme case that PCPC might experience, and the method is suitable for a comparison study of the PCPC F-T durability.

Table 8: Summary of F-T test results Mix Descriptions F-T cycles to failure 1A 3/8 RG-7% sand 136 2 #4 RG 153

2A #4 RG-7% sand >300, 2.1%weight loss at 300 cycles 2C #4 RG-7% sand-10% latex replacement 216 2F #4 RG -0.30 kg/m3 fiber 201 2G #4 RG -0.89 kg/m3 fiber 181 2H #4 RG-7% sand-0.89 kg/m3 fiber Test is in progress; less weight loss than sample Mix 2A 3 3/8 LS 196

3A 3/8 LS-7% sand 110 3B 3/8 LS-7% sand-10% latex 110

Table 8 summarizes the F-T test results of the PCPC mixes presented in the paper. Among these mixes, Mix 2H (with #4RG, 7% sand, and 1.5 lb/yd3 fiber) is currently showing the highest F-T resistance, which had 0.4% weight loss after subjected to about 180 F-T cycles. Mix 2A (with #4 RG, 7% sand) is the second to the highest, which had 0.8% weight loss at 180 F-T cycles and 2.3% weight loss at 300 F-T cycles. Mix 2C (with #4RG, 7% sand, and 10% latex replacement) comes to the third, which reached 15% weight loss at 216 F-T cycles. These results imply that when properly designed and constructed, PCPC can have an excellent serviceability under cold weather conditions. Discussion Relationships among the PCPC Properties. Figures 2-7 illustrate the relationships among the PCPC properties tested. Most of the relationships are similar to those of conventional concrete.


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0

500

1,000

1,500

2,000

2,500

3,000

3,500

4,000

0.1 0.2 0.3 0.4 0.5 0.6

Aggregate Size (in.)

7-da

y C

ompr

essi

ve S

tren

gth

(psi

) 1/2 inch sieve

3/8 inch sieveNo. 4 sieve

Void Ratio (%)

10 15 20 25 30 35U

nit W

eigh

t (kN

/m3 )

16

17

18

19

20

21

22

Uni

t Wei

ght (

pcf)

105

110

115

120

125

130

135

140Unit Weight (kN/m3) = 24.19 - 0.2177 * Void Ratio

R2 = 0.92

Figure 2: Relationship between unit weight and void content

y = 13.257e0.1579x

R2 = 0.6522

0

500

1000

1500

2000

2500

3000

10 15 20 25 30 35

Void Content (%)

Wat

er P

erm

eabi

lity

(in./h

r)

Figure 3: Relationship between permeability and void content

Figure 4: Relationship between coarse aggregate size and PCPC 7-day Strength (River Gravel)


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Void Ratio (%)

10 15 20 25 30

7-da

y co

mpr

essi

ve s

treng

th (M

Pa)

10

12

14

16

18

20

22

24

26

28

7-da

y co

mpr

essi

ve s

treng

th (p

si)

1500

2000

2500

3000

3500

4000

4.75 mm (No. 4), RG9.5 mm (3/8 in.), RG4.75 mm (No. 4) PGBest FIt

Strength (MPa) = 33.45 - 0.725 * void ratioR2= 0.73

Void ratio (%)

20 22 24 26 28 30 32 34 36

7-da

y co

mpr

essi

ve s

treng

th (M

Pa)

8

12

16

20

24

28

7-da

y co

mpr

essi

ve s

treng

th (p

si)

1500

2000

2500

3000

3500

4000

9.5 mm (3/8 in.)Best Fit

Strength (MPa) = 49.95 - 1.181 * Void ratio

R2 = 0.97

(a) river gravel and pea gravel (b) crushed limestone

Figure 5: Relationship between void content and 7-day compressive strength

R2 = 0.68

100150200250300350400450500

1000 2000 3000 4000

28-day Com pressive Strength, ps i

28-d

ay S

plitt

ing

Stre

ngth

, ps

i

Figure 6: Relationship between compressive and splitting strength

0

50

100

150

200

250

300

350

1000 2000 3000 4000

28-day Com pressive Strength, ps i

# of

F-T

Cyc

les

to F

ailu

re

0

50

100

150

200

250

300

350

100 200 300 400 500

28-day Splitting Strength, psi

# of

F-T

Cyc

les

to F

ailu

re

(a) F-T durability vs. compressive strength (b) F-T durability vs. splitting strength

Figure 7: Relationship between strength and F-T durability


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Figure 2 shows that unit weight of the PCPC studied decreased linearly with void content. Figure 3 illustrates that the permeability of the concrete increased exponentially with the concrete void content. As a result, the unit weight test can serve as a simple, quick quality control test in field to ensure proper void content or permeability of the concrete. Figures 4 and 5 demonstrate the relationships between aggregate size, void content, and 7-day compressive strength of PCPC. There is a trend (Figure 4) that 7-day compressive strength of PCPC decreases with increased coarse aggregate particle size, which is similar to what is observed in conventional concrete and largely due to the weak interfacial transition zone between the cement paste the large size aggregate. Because of the reduced effect cross section area, the 7-day compressive strength of PCPC also decreases with the void content of the concrete (Figure 5).

Figure 6 illustrates an acceptable linear relationship (R2=0.74) between the 28-day compressive and splitting tensile strength of the PCPC tested. If all the test data are considered, there is no clear relationship between the concrete strength and F-T durability (Figure 7). However, if one data point is taken away (Mix 3, in hollow), Figure 7b demonstrates a good relationship between the PCPC splitting/tensile strength and F-T durability. Therefore, the splitting tensile strength test results can serve as preliminary evaluations for the F-T resistance of PCPC. PCPC Mix Design Criteria and Considerations. The mix design criteria and procedure for PCPC are under development. In the consideration of PCPC function (permeable) and application (carrying traffic loads and exposed to a mild or cold weather condition), permeability, strength, and F-T durability of PCPC should be considered simultaneously in the concrete mix design. Table 9 summarizes the related PCPC properties from literature.

Table 9: PCPC properties from literature Void Ratio

Unit Weight lb/ft3

Permeability in/hour

28-day Compressive

Strength

Flexural Strength Reference

(%) (kg/m3) (cm/sec ) psi (MPa) psi (MPa)

United States

15 to 25 100 - 125

(1602 -2002) 288 -756

(0.203-0.533) 800 -3000 (5.5 -20.7)

150- 550 (1.03 -3.79) Tennis et al. 2004

15 to 35 NA NA NA 363- 566

(2.50 -3.90) Olek and Weiss 2003

International

19 NA NA 3771 (26.0) 638 (4.4) Beeldens et al. 2003

20 to 30 118- 130

(1890-2082) NA 2553 -4650 (17.6-32.1)

561 825 (3.87- 5.69 ) Beeldens 2001

NA NA NA 2756 (19.0) NA Tamai and Yoshida 2003

11 to 15 NA 36-252

(0.025-0.178) NA 606- 1085

(4.18 -7.48 ) Kajio et al. 1998

18 to 31 NA NA 1595-3626 (11.0 -25.0) NA Park and Tia 2004

NA = not available


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Based on the results from available literature and the present study, the performance-based mix design criteria for PCPC in a cold weather climate are proposed as follows:

(1) water permeability: 140 in./hour (0.1 cm/sec ) (2) compressive strength at 28 days: 3000 psi (20 MPa ) (3) F-T durability (based on ASTM C666-Procedure A): 5% after 300 F-T cycles.

These preliminary mix design criteria should be verified in field, and other important durability issues, such as clogging and wearing resistance, may be considered in the mix design in future. In order to meet the above permeability criterion, larger than 140 in/hour (0.1 cm/sec ), selecting coarse aggregate with proper void content is very important. Based on the present study, the void content of raw coarse aggregate should be higher than 35%. In the present study, a raw coarse aggregate, #4RG, had void content of 38.5%. The void content of the PCPC made with this aggregate was 25.3%, decreased approximate 10% when compared with raw aggregate. After replacing 7% of the coarse aggregate with sand (for strength and durability improvement), the corresponding PCPC had another deduction in the void content by 10%. As a result, the PCPC mix (Mix 2A: #4 RG with 7% sand) had void content of 18.5% and permeability of 140 in./hour (0.1 cm/sec ). This sequential deduction of void content may provide engineers with an insight to aid selection of raw aggregate materials in PCPC mix design. There are many factors affecting concrete strength, such as concrete materials, w/c, mixing and consolidation methods, some of which (such as consolidation) are discussed by authors in a separate paper. To meet the PCPC strength criterion above, using small amount of sand (7% weight of total aggregate in the present study) is recommended for the concrete permeability and cost considerations. The recommend w/c is 0.27 or lower; however, it can be further reduced if workability of the concrete is improved. The cement content should be just enough to coat the aggregate particles with a thin layer. In the present study, cement content of 570 lb/cy (338 kg/m3 ) was used for most mixes. The calculated average paste thickness around aggregate particles in these PCPC mixes is approximate 0.008 (200 micrometer). Excessive cement may seal the voids between aggregate particles and significant reduces permeability of the concrete. However, cement content may vary when different aggregate is used. For conventional concrete, F-T resistance of concrete largely depends on aggregate quality, concrete air void system (especially the void spacing factor) and strength (especially the strength of the interfacial transition zone between aggregate and cement paste). It is well accepted that concrete with void spacing factor of 0.008 (200 micrometer) generally has good F-T resistance. In PCPC, void system may be less important due to the open structure of the material. As mentioned above, the calculated average paste thickness around aggregate particles in the most PCPC mixes studied is approximate 0.008 (200 micrometer), which indicates that requirement for AEA might be arbitrary. However, it was observed under microscope that the paste thickness in some regions of the PCPC was often larger than the average value. Therefore, AEA is still recommended for the PCPC application under a cold weather condition until further research is conducted. Figure 7 has shown that PCPC F-T durability increases with concrete strength, especially the splitting tensile strength. Addition of micro-fiber or latex generally increases concrete tensile strength, and it therefore is recommended for the PCPC in the cold weather climate region. (Note that some latex modified PCPC in the present study did not perform well during the F-T tests,


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which is probably because the latex was used for cement replacement, rather than addition.) Based on the present study, the recommend 28-day splitting tensile strength value for the PCPC in the cold weather climate region is 360 psi (2.5 MPa) and higher. Concluding Remarks In the present paper, effects of concrete materials (coarse aggregate, sand, cementitious materials, fibers, and latex) and mix proportions on PCPC functional properties (permeability and strength), quality control properties (void content and unit weight), and F-T durability are evaluated. The relationships between these properties are explored. The PCPC mix design criteria and considerations are discussed. The study concludes that when properly designed and constructed, PCPC can have an excellent serviceability under cold weather conditions. Proper strength and F-T durability of PCPC can be achieved by use small amount of sand and micro-fibers in the concrete. References Beeldens, A,. Van Gemert, D., and Caestecker, C. (2003). Porous Concrete: Laboratory Versus Field

Experience. Proceedings 9th International Symposium on Concrete Roads, Istanbul, Turkey. Kajio, S., Tanaka, S., Tomita, R., Noda, E., and Hashimoto, S. (1998). Properties of Porous Concrete with

High Strength, Proceedings 8th International Symposium on Concrete Roads, Lisbon, pp 171-177.

National Ready Mixed Concrete Association (NRMCA). (2004). Freeze-Thaw Resistance of Pervious

Concrete. Olek, J., and Weiss, W. J., (2003). Development of Quiet and Durable Porous Portland Cement Concrete

Paving Materials. Final Report SQDH 2003-5 Center for Advanced Cement Based Materials, Purdue.

Park, S., and M. Tia. (2004). An experimental study on the water-purification properties of porous concrete. Cement and Concrete Research 34,177-184

Ramakrishnan, V. (1992) Latex-Modified Concrete and Mortars, NCHRP Synthesis 179,

Transportation Research Board, National Research Council, Washington, D.C. Tamai, M., and Yoshida, M. (2003). Durability of Porous Concrete. Paper presented at the Sixth

International Conference on Durability of Concrete, American Concrete Institute. Tennis, P.D., Leming, M.L., and Akers, D.J. (2004). Pervious Concrete Pavements, Special Publication

by the Portland Cement Association and the National Ready Mixed Concrete Association. United States Department of Agriculture (USDA). (1986). Technical Release 55: Urban

Hydrology for Small Watersheds. Youngs, Andy. (2005). Pervious Concrete Its for Real. Presentation at Pervious Concrete and Parking

Area Design Workshop, Omaha.

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Pervious Concrete Mix Design