Third International Conference on Construction In Developing Countries (ICCIDC III) Advancing and Integrating Construction Education, Research & Practice July 4-6,2012Bangkok, Thailand Investigation of Pervious Concrete Made with Locally Available Materials Ariful Hasnat (University of Asia Pacific, Dhaka, Bangladesh, arifulhasnat@gmail.com) Tarek Uddin Mohammed (University of Asia Pacific, Dhaka, Bangladesh, tarek@uap-bd.edu) Mohammad Naim Hossain (Anan Construction,Dhaka, Bangladesh, naimhossain27@yahoo.com) Nabeel Rahman (Multiplan Development Limited, Dhaka, Bangladesh,nabeel2929@gmail.com) Hidenori Hamada (Kyushu University, Fukuoka, Japan,h-hamada@doc.kyushu-u.ac.jp) Abstract Due to the construction of buildings and other infrastructures in the major cities in Bangladesh, it is found that the uncovered ground area for infiltration of rain water to ground water reservoir is reduced significantly. On the other hand, continuous sucking of ground water from underground reservoir results in depletion of ground water level year by year. This environmental problem can be reduced by application of porous concrete on parking areas, walkways, and roads for light vehicles, etc. With this background, this study on pervious concrete has been planned. Cylinder concrete specimens of diameter 100 mm and height 200 mm were made with locally available coarse aggregates(1 st class brick aggregate, crushed stone aggregate, and recycled brick aggregate). Variables include type of aggregate and gradation of aggregate. Cement content was 300 kg/m 3 and water-to-cement ratio was 0.33. Test items include void in aggregate, unit weight of aggregate, specific gravity of aggregate, compressive and tensile strength of pervious concrete at 28 days and permeability of water through the pervious concrete. The experimental results revealed that compressive strength as well as tensile strength of pervious concrete is inversely proportional to the permeability. Within the scope of this investigation, pervious concrete with compressive strength range from 650 to 1700 psi and permeability from 60 to 15 mm/sec can be made. The results clearly indicated that pervious concrete can be used on parking, walkways, and roads for light weight vehicles. Keywords Compressive Strength, Gradation, Permeability, Pervious Concrete, Tensile Strength. 1. INTRODUCTION According to definition specified by ACI 522 committee, pervious concrete refers to a zero-slump, opengraded material consisting of portland cement, coarse aggregate, little or no fine aggregate, with or without admixtures and water. Use of uniform coarse aggregate and little or no fine aggregate gives pervious concrete much higher porosity and permeability than conventional concrete, which enables 548
quick drainage of stormwater (Tennis et al, 2004). Therefore, pervious concrete is a very effective stormwater management tool to reduce the volume of stormwater runoff and the concentration of pollutants. The earliest record of use of pervious concrete is in the United Kingdom, where two houses were constructed using coarse gravel and cement (Malhotra, 1976). Due to the construction of buildings and other infrastructures in the major cities in Bangladesh, it is found that the uncovered ground area for infiltration of rain water to ground water reservoir is reduced significantly. On the other hand, continuous sucking of ground water from underground reservoir results in depletion of ground water level year by year. This environmental problem can be reduced by application of pervious concrete on parking areas, walkways, and roads for light vehicles, etc. With this background, this study on pervious concrete has been planned. 2. EXPERIMENTAL WORK 2.1 Materials Three types of locally available aggregate ((1 st class brick (FB), crushed stone (CS), and recycled brick aggregate (RB)) were used in this study. The properties of these aggregate are summarized in Table 1. Pervious concrete used in this study was prepared using 10 different aggregate gradations. The cement used in this study was CEM II/A-M as per BDS EN 197-1. Tap water was used for all mixture. All mixture had a water-to-cement ratio 0.33 and cement content 300 kg/m 3. The mixture proportions are summarized in Table 2. Thirty different cases were investigated by varying type of aggregate (CS, FB, and RB) and gradation of coarse aggregate. Mixture ID 100#3/8 indicates 100% of coarse aggregate (CA) is retained on 3/8 sieve. Similarly mixture ID 50#4 50#8 indicates 50% of CA is retained on #4 sieve and 50% on #8 sieve. Table 1: Summary of Aggregate Properties Items ASTM Type of Aggregate Specifications FB CS RB Specific gravity (SSD) C127 2.02 2.67 2.20 Absorption capacity (%) C127 25.81 7.35 18.82 Loss Angeles abrasion (%) C131 (Grade B) 41.6 36.8 41.0 Table 2: Mixture Proportions of Pervious Concrete Aggregate Type FB CS RB Mixture ID Unit Content (kg/m 3 )* TV Unit Content (kg/m 3 )* TV* Unit Content (kg/m 3 )* TV C W CA * % C W CA % C W CA * % 100 #3/8 1064 27.1 1553 21.6 992 34.7 100#4 1042 28.2 1470 24.7 895 39.1 100#8 967 31.9 1452 25.4 1010 33.8 75#3/8 25#4 1125 24.1 1657 17.7 1085 30.4 75#4 25#8 1071 26.7 1528 22.5 981 35.2 300 99 300 99 300 99 25#3/8 75#8 1068 26.9 1585 20.4 1082 30.6 25#4 75#8 1014 29.6 1484 24.2 1010 33.8 50#3/8 50#4 1082 26.2 1567 21.1 981 35.2 50#3/8 50#8 1093 25.7 1578 20.7 1103 29.6 50#4 50#8 1039 28.3 1499 23.6 996 34.5 * C=Cement, W=Water, CA=Coarse aggregate, and TV=Theoretical void. 549
2.2 Mixing, Casting, and Curing of Concrete A 200 liter pan type concrete mixer was used for mixing concrete. Based on the amount of concrete needed for casting cylinders and other specimens, the amount of materials (cement, water, CA) needed are calculated and measured by using a digital weight balance. SSD coarse aggregates (CA) were used. Cylinder concrete specimens (100 mm x 200 mm) were made as per ASTM C192. The freshly consolidated concrete specimens were kept under wet jute bags for one day. After one day, the samples were demolded from the mould and kept under wet jute bags. Before one day of testing, the concrete samples were kept under water. Before testing, the samples were removed from the water and water from the surface was wiped out and then tested for necessary investigations. A total of 180 concrete cylinder specimens were made for this study. 2.3 Testing Methods Compressive and split-tensile tests were performed on the relevant specimens as per ASTM C39 and ASTM C496, respectively. To measure void in concrete, the cylinder specimen was immersed in water jar marked with a scale and the increased volume of water was measured. The air bubbles were removed by gently shaking the cylinder. The interconnected porosity was calculated by using the following equation: Where, V 0 is the percentage of void in concrete, V 1 is the volume of cylinder with void and V 2 is the volume of increased water container due to immersion of cylinder.since pervious concrete has a large interconnected pore network, the conventional methods that are used to evaluate the hydraulic conductivity of normal concrete are not directly applicable. To estimate the hydraulic conductivity of pervious concrete, a falling head permeability cell has been designed (Hossainet al, 2010). The coefficient of permeability (k) was calculated by using the following equation: Where, a and A are cross sectional areas of the cross-section of the sample and the tube respectively and L is the length of the specimen, h 1 and h 2 is the initial and final head, and t is the time required for water to fall from initial head to final head. (1) (2) 3. RESULTS AND DISCUSSION Unit weight of concrete for different mix proportions are shown in Figure 1.The results revealed that the unit weight of pervious concrete varied with respect to the gradation of CA and the type of aggregate. It is observed that pervious concrete made with CS shows higher unit weight with an average of 1885 kg/m 3 compared to FB and RB pervious concrete. Pervious concrete made with FB varied from 1380 kg/m 3 to 1730 kg/m 3 with an average value of 1520 kg/m 3. Pervious concrete made with RB varied from 1450 kg/m 3 to 1600 kg/m 3 with an average value of 1510 kg/m 3. According to ACI 213R-87 concrete which has unit weight equal or below 1840 kg/m 3 is categorized as light weight concrete which indicates that pervious concrete made with FB or RB can also be categorized as light weight concrete. Percetage void of pervious concrete with different type of aggregate is shown in Figure 2(a). The percentage void of pervious concrete varied widely. It is observed that, pervious concrete with large size aggregtae shows more interconncected void than other mixes. It is also observed that, pervious concrete made with RB shows higher interconnected pores, it is due to blunt edge of the RB. Further research is necessary to give a conclusion with this respect. Percentage void of pervious concrete made with CS 550
varied from 10% to 27% with an average 20%. Percentage void of pervious concrete made with FB varied from 12% to 28% with an average of 20%. Percentage void of pervious concrete made with RB varied from 12% to 31% with an average of 21%. According to ACI 522-06 the typical void content of pervious concrete can range from 15% to 35%. Most of the mix proportions (Table 2) satisfy the ACI specification. Permeability of pervious concrete made with different type of aggregate is shown in Figure 2(b). Similar to percentage void, permeability of pervious concrete made with RB is higher in most of the cases. Permeability of pervious concrete made with CS varied from 15 mm/sec to 59 mm/sec with an average 31 mm/sec. Permeability of pervious concrete made with FB varied from 16 mm/sec to 51 mm/sec with an average of 27 mm/sec. Permeability of pervious concrete made with RB varied from 17 mm/sec to 49 mm/sec with an average of 30 mm/sec. Compressive strength ofpervious concrete made with different type of aggregate is shown in Figure 3(a). According to ACI 522-06, compressive strength of pervious concrete varies from 400 psi to 4000 psi. Present research indicates that compressive strength of pervious concrete made with CS varied from 760 psi to 1740 psi with an average 1130 psi. Compressive strength of pervious concrete made with FB varied from 630 psi to 1000 psi with an average 820 psi. Compressive strength of pervious concrete made with RB varied from 800 psi to 1000 psi with an average 900 psi. Pervious concrete made with CS shows higher compressive strength compared to FB and RB. RB shows higher average compressive strength compared to FB. It is due to the rough and porous texture of recycled aggregate which gives good bonding with cementecious matrix (Jiusu, 2011). Figure 1: Unit Weight of Pervious Concrete Made with Different Aggregates Figure 2: Pervious Concrete Made with Different Aggregates (a)percentage Void (Left), (b) Permeability (Right) 551
Same as compressive strength, pervious concrete made with CS shows higher tensile strength compared to other two aggregates (FB and RB) as shown in Figure 3(b). Tensile strength of pervious concrete made with CS varied from 150 psi to 245 psi with an average 200 psi. Tensile strength of pervious concrete made with FB varied from 130 psi to 210 psi with an average 170 psi. Tensile strength of pervious concrete made with RB varied from 125 psi to 200 psi with an average 170 psi. The variation of tensile strength and compressive strength for different type of aggregates are shown in Figure 4. Relationships between compressive strength and tensile strength of pervious concrete for different aggregates are also shown in Figure 4. It is observed that, pervious concrete made with FB and CS has similar relationship with respct to compressive strength and tensile strength. The variation of permeability and compressive strength for different type of aggregates are shown in Figure 5.Relationships between permeability and compressive strength of pervious concrete made with diiferent aggregatesare shown in Figure 5. It is observed that, compressive strength is inversely related to permeability of pervious concrete. Unusual result is observed in permeability and compressive strength relationship for pervious concrete made with RB. Further research is necessary on this matter. Figure 3: Pervious Concrete Made with Different Aggregates (a) Compressive Strength (Left), (b) Tensile Strength (Right) Figure 4: Relationships between Compressive Strength and Tensile Strength of Pervious Concrete Made with Different Aggregates 552
Figure 5: Relationships between Compressive Strength and Permeability of Pervious Concrete Made with Different Aggregates 4. CONCLUSIONS The following conclusions are made based on the scope of this study: (1) Percentage void of pervious concrete can be increased or decreased by changing the gradation and type of aggregate, (2) All investigated cases meet the specifications of ACI with respect to strength, percentage void and permeability, (3) Recycled aggregate (RB) can be a good choice for making pervious concrete, (4) Pervious concrete can be used on parking, walkways, and roads for light weight vehicles like passenger car, rickshaw, and auto rickshaw. 5. ACKNOWLEDGEMENTS The data accumulated in this report have been accumulated from several undergraduate thesis papers. The authors acknowledge the efforts of the students to gather the laboratory and field data related to this study. This study was conducted with the financial supports from the University of Asia Pacific (UAP), Dhaka, Bangladesh under a project on Sustainable Development of Construction Works in Bangladesh. 6. REFERENCES ACI 522-R(2006). American Concrete Institute, Farmington Hills, USA. ACI 213-R (1987). American Concrete Institute, Farmington Hills, USA. Hossain, M. N., Rahman, N., Mamun, A. A., and Iftekhar, M. (2010). A study on pervious concrete for application in Bangladesh, B.Sc. Thesis, University of Asia Pacific, Dhaka, Bangladesh. Jiusu, L. (2011). Theoretical compressive strength of pervious recycled aggregate concrete. Energy Procedia, Vol. 11, pp. 3547-3552. Malhotra, V.M. (1976). No-fines concrete-its properties and applications. ACI Journal, Vol. 73, No. 1, pp. 628-644. Tennis, P. D., Leming, M. L., and Akers, D. J. (2004). Pervious concrete pavements, Portland Cement Association and National ReadyMixed Concrete Association, pp. 4. 553