EVALUATION OF STRENGTH, PERMEABILITY AND VOID RATIO OF PERVIOUS CONCRETE WITH CHANGING W/C RATIO AND AGGREGATE SIZE

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1 International Journal of Civil Engineering and Technology (IJCIET) Volume 7, Issue 4, July-August 2016, pp Article ID: IJCIET_07_04_023 Available online at ISSN Print: and ISSN Online: IAEME Publication EVALUATION OF STRENGTH, PERMEABILITY AND VOID RATIO OF PERVIOUS CONCRETE WITH CHANGING W/C RATIO AND AGGREGATE SIZE Tejas Joshi Research Scholar, Civil Engineering Department, Institute of Technology, Nirma University, Ahmedabad , Gujarat, India Dr. Urmil Dave Professor, Civil Engineering Department, Institute of Technology, Nirma University, Ahmedabad , Gujarat, India ABSTRACT Pervious concrete strength and permeability mainly depend on aggregate size and proportion of the materials. This paper discusses various combination of pervious concrete with different aggregate size and watercement ratio. Three aggregate sizes 6-10mm, 10-20mm and 50% mix of both sizes are taken. Water-cement ratio of 0.30, 0.35 and 0.40 were used for each aggregate size. The objective of this investigation is to study the effect of variation in aggregate size and water-cement ratio on pervious concrete. For the measurement of permeability testing setup is developed based on falling head method. The experimental investigation was carried out to evaluate the density, compressive strength and permeability and void ratio. The compressive strength pervious concrete showed an increase in water/cement ratio increased. The compressive strength of pervious concrete is less than conventional concrete. The void ratio is to be found in range of 25% to 32%, which is sufficient for pervious concrete. Similarly, permeability of pervious concrete decrease using small size of aggregate. Based on study it was found that with using 0.3 w/c ratio and Mix (50%) aggregate gives better result for pervious concrete. Key words: Aggregate Size, Water Cement Ratio, Void Ratio, Compressive Strength, Permeability

2 Evaluation of Strength, Permeability and Void Ratio of Pervious Concrete with Changing W/C Ratio and Aggregate Size Cite this Article: Tejas Joshi and Dr. Urmil Dave, Evaluation of Strength, Permeability and Void Ratio of Pervious Concrete with Changing W/C Ratio and Aggregate Size. International Journal of Civil Engineering and Technology, 7(4), 2016, pp INTRODUCTION Pervious concrete is also named as porous concrete or permeable concrete. In pervious concrete, carefully controlled amount of water and cementitious materials are used to create a paste that forms a thick coating around aggregate particles. A pervious concrete mixture contains little or no sand which create a substantial void content in it. Using sufficient paste to coat and bind the aggregate particles together creates highly permeable system with interconnected voids which drains quickly. The proper utilization of pervious concrete is a recognized Best Management Practice by the U.S. Environmental Protection Agency (EPA) for providing first-flush pollution control and storm water management 1.1. LITERATURE REVIEW ACI [1] recommended that the falling head method developed by Neithalath could be used to determine the water permeability of pervious concrete. Typical void ratio for pervious concrete is 18-35% (ACI, 2010; Tennis et al 2004)[1,2]. This range is considered ideal to provide enough strength, while allowing for sufficient hydraulic conductivity. Void ratio was shown to increase with a decrease in aggregate to cement ratio Park & Tia, [3]. The void content is defined as the total percentage of voids present by volume in a specimen. As porosity increases, permeability increases and compressive strength decreases and vice versa. The void content is generally between 15-25% and permeability is generally between 2-30 mm/s. [4] The densities are in the order of 1600 Kg/m 3 to 2000 Kg/m 3 [4] is common with the typical compressive strength in the range of 2.8 MPa to 28 MPa.[4] 1.3. NEED OF STUDY Pervious concrete is an answer for taking out storm water runoff. The high level of porosity in pervious concrete adequately minimizes runoff. The design of each pervious concrete mixture is unique based on the performance requirements. Therefore, this study includes different parameters to develop a pervious concrete mixture proportion. With all the possibilities from varying w/c ratio and aggregate size with fixed cement content. Experimental results are to be useful for development of pervious concrete. 2. MATERIALS AND METHODS 2.1. Ordinary portland cement Ordinary Portland cement, as per Indian Specifications IS 8112:1889 [6] was used for this investigation. The physical properties of are presented in Table Aggregate Locally available 6mm-10 mm and 10mm-20 mm crushed aggregates have been used as coarse aggregates. Two sizes of crushed angular aggregate were used in this editor@iaeme.com

3 Tejas Joshi and Dr. Urmil Dave investigation. They were tested as per Indian Standard Specifications IS 383:1970 [7]. Their physical properties are given in Table 2. Table 1 Physical properties of ordinary Portland Cement Properties For 53 grade OPC Result Specification in IS Achieved 12269:1987 Fineness in m 2 /kg 351 Min 225 Soundness By Le chatelier method in mm 0.4 Max 10 Initial setting time in minutes 35 Min 30 Final setting time in minutes 240 Max days compressive strength in MPa Min 27 7 days compressive strength in MPa Min days compressive strength in MPa Min 53 Specific Gravity Table 2 Physical properties of coarse aggregate Sr. No. Properties Coarse Aggregate 1 Specific Gravity Unit weight (kg/m 3 ) MIX PROPORTION Proportions of pervious concrete mixture was done to produce concrete having adequate workability, strength, permeability and void ratio. The mix proportions for pervious concrete mixture cement content was 375 kg/m 3 and Cement: Aggregate ratio 1:4 is kept constant for all mixes. For experimental investigation as shown in Table 3 three set of aggregate sizes are taken such as 10-20mm, 10-6mm and in the third set both aggregates in equal proportion are used. In each set three water-cement ratio 0.30, 0.35 and 0.40 are used. These mixture were used throughout the study. 4. EXPERIMENTAL PROGRAM 4.1. Preparation of Specimens Pervious concrete specimens were prepared using 150 mm x 150mm x 150mm moulds. The specimens cast were demoulded after 24 hours and kept in normal curing for the required age such as 7 and 28 days. Table 3 Pervious concrete Mix proportions for Different Size of Aggregate Mix Name Aggregate Size Water/cement Ratio Mix Mix mm 0.35 Mix Mix Mix mm 0.35 Mix Mix mm (50%) Mix mm (50%) 0.35 Mix Cement Content Aggregate 375 kg/m kg/m editor@iaeme.com

4 Evaluation of Strength, Permeability and Void Ratio of Pervious Concrete with Changing W/C Ratio and Aggregate Size 4.2. Compressive Strength Test The compressive strength of pervious concrete has been evaluated on hydraulic testing machine. For the compressive strength test, cubes of size 150mm x 150mm x 150 mm are tested in compression in accordance with the test procedures given in IS : [8] Permeability Test For the measurement of the permeability of pervious concrete instrument is suggested by the ACI-522R [1]. The falling head method was used to measure the water permeability. Figure 1 shows the schematic diagram of the permeability test setup. 300 mm water heads were adopted for measuring permeability of pervious concrete. For measuring permeability of pervious concrete cylinder of size 150 x 150 mm are casted. Cylinders are casted in the PVC pipe. In this study permeability of pervious concrete is measured at the end of the 28 days. Permeability of pervious concrete is calculated using equation 1. A1l h k = log A t h Where, k = water permeability A 1 =cross-sectional area of the specimen (150mm) A 2 = cross-sectional areas of the tube (150mm) l = length of the specimen (150 mm) t = time =17.75s h 1 = the initial water head (300mm) h 2 = the final water head (1 mm) (1) log = mm / s Figure 1 Falling Head Apparatus editor@iaeme.com

5 Tejas Joshi and Dr. Urmil Dave 4.4. Void Ratio The void content was determined according to the ASTM C1688 [5]. The void content is defined as the total percentage of voids present by volume in a specimen. The void content of pervious concrete is calculated using equation 2. Void content (%) = 100 (2) Where, D = (M c -M m )/V m (Density) M c = mass of measure filled with concrete M m = net mass of concrete by subtracting mass of measure V m = volume of measure T = Ms/Vs (Theoretical Density) Ms = total mass of materials batched Vs = total absolute volume of materials *Sample calculation For making 3 cubes by using 250 kg/m 3 cement content with and 0.3 w/c, following are the requirements. Cement = kg. Aggregates = 16.9 kg. Sand = 0 kg. Water = 1.12 kg. This sample calculation includes 6-10 mm size of aggregates with 375 kg/m 3 cement content, 0.3 w/c ratio. The values below are the average of 3 cubes. M c -M m = kg V m = 0.15 x 0.15 x 0.15 m 3 = m 3 D = 5.265/ = 1880 kg/m 3 D = 1560 kg/m 3 T=( )/((3.725/(3.15*1000))+(16.9/(2.71*1000))+(0/(2.66*1000))+ (1.12/(1*1000))) T = 2531 kg/m 3. Void content (%) = (( )/2531)*100 = 38.4% Density Density of pervious concrete has been evaluated by ratio of weight of cube to the volume of cubes. D = weight of cube/ volume of cube 5. RESULTS AND DISCUSSIONS Table 4 shows the experimental results for Pervious Concrete at the age of 7 days for density, compressive strength and void content for combination of different aggregate size respectively. Table 5 includes the experimental results for Pervious Concrete at the age of 28 days respectively for density, compressive strength, permeability and void content respectively editor@iaeme.com

6 Evaluation of Strength, Permeability and Void Ratio of Pervious Concrete with Changing W/C Ratio and Aggregate Size Table 4. 7 days results for pervious concrete Cement (kg/m 3 ) 375 Aggregate mm 10-6 mm (50%)mm and 10-6mm50% w/c Compressive Strength (MPa) Void Content (%) Density (kg/m 3) Cement (kg/m 3 ) 375 Aggregate mm 10-6 mm (50%) mm and 10-6mm (50%) Table days results for pervious concrete w/c Compressive Void Density Permeability Strength (MPa) Content (%) (kg/m 3) (mm/s) Effect of w/c ratio on compressive strength of pervious concrete The compressive strength of pervious concrete increases with increase in w/c as shown Figure 2. Maximum increase in compressive strength was achieved by using 0.4 w/c ratio and aggregate size used mix in grading. Figure 2 shows the maximum compressive strength MPa achieved using w/c ratio is 0.4. Table 4 and 5 summarises the compressive strength of pervious concrete mixes. In Table 5, the pervious concrete showed the significantly lower strength as compared to the normal concrete. As expected, pervious concrete resulted in lower compressive strength due to its high void content compare to control concrete editor@iaeme.com

7 Tejas Joshi and Dr. Urmil Dave Figure 2 Effect of w/c on pervious concrete compressive strength 5.2. Effect of w/c ratio on void content of pervious concrete (28 days) Figure 3 Effect of w/c on pervious concrete void content The influence of void ratio on pervious concrete is shown Figure 3. It has been observed that with increase in w/c ratio, void content of pervious concrete reduce. The void ratio of pervious concrete is influenced by grading of aggregate and compaction method. The void content in pervious concrete is mainly large size of air void. Figure 3 shows that combined aggregate size gives more void ratio and compressive strength Effect of w/c on Permeability for Pervious Concrete (28days) The water permeability under 300 mm water head summaries Table 5. Figure 4 shows that w/c ratio is increased and permeability decreased for pervious concrete. It has been observed that mm aggregate size gives higher values of permeability. Figure 4 showed that permeability found in range of 12.14mm/s to 20.93mm/s. The water permeability of pervious concrete is significantly influenced by pore structure which is affected by compaction and grading editor@iaeme.com

8 Evaluation of Strength, Permeability and Void Ratio of Pervious Concrete with Changing W/C Ratio and Aggregate Size Figure 4 Effect of w/c on permeability of pervious concrete 5.4. Effect of w/c on Density of Pervious Concrete Figure 5 Effect of w/c on density of pervious concrete Density of pervious concree was achieve in experimental investigation ranges from 2000 to 2240 kg/m 3.Figure 5 shows that 0.4 w/c ratio gives maximum density values of pervious concrete. It has been observed that with increase in w/c ratio, density of pervious concrete increases. Density of pervious concrete is depend on w/c ratio and method of compaction. 6. CONCLUSION The following conclusionss are drawn based on the experimental investigations carried out on pervious concrete. It was found that with using 0.3 w/c ratio and Mix (50%) aggregate gives better result for pervious concrete. For that particular mix void content 35.12% were found. It has been observed that density increased lead to increase in compressive strength of the pervious concrete editor@iaeme.com

9 Tejas Joshi and Dr. Urmil Dave It has been concluded that larger size of aggregate reduces the compressive strength of pervious concrete. Mixing of smaller and bigger size of aggregate gives better compressive strength than a single size of aggregate. In mix aggregate smaller aggregate fill the gap between the bigger aggregate in pervious concrete and might cause the increase in compressive strength. REFERENCE [1] ACI Commmittee 522 (2006). Pervious concrete, ACI International, Farmington Hills. [2] Tennis, P.D, M.L. Leming, and D.J. Akers, Pervious concrete pavements. Portland cement Association, Skokie, Illinois, & National Ready Mixed Concrete Association, Silver Spring, Maryland, [3] Sung-Bum Park, and Mang Tia (2013), An experimental study on the waterpurification properties of porous concrete, Cement and Concrete Research P.NO [4] NRMCA. (2004). "What, why, and how? Pervious concrete, Concrete in Practice Series. CIP 38. [5] ASTM C1688 Standard Test Method for Density and Void Content of Freshly Mixed Pervious Concrete. [6] IS 8112:1989. Specifications for 53grade Portland cement, New Delhi, India: Bureau of Indian Standards. [7] IS: Specification for Coarse and fine aggregate from natural sources for concrete, New Delhi, India: Bureau of Indian Standards. [8] OSENI O. W. and AUDU T.M., The Effects of Percentage Compositon of Millet Stem Ash (MSA) and Water Cement Ratio on The Properties Composite Concrete, International Journal of Civil Engineering and Technology, 7(1), 2016, pp [9] S. Rajesh Kumar, Characteristic Study On Pervious Concrete, International Journal of Civil Engineering and Technology, 6(6), 2015, pp [10] T.C. Nwofor and D.B. Eme, Appraisal on The Strength of Concrete Produced with Varying Aggregate Size, International Journal of Civil Engineering and Technology, 7(3), 2016, pp [11] Bhavneet Singh, Bleeding In Concrete, International Journal of Civil Engineering and Technology, 4(2), 2015, pp [12] K. Krishna Bhavani Siram and K. Arjun Raj, Concrete + Green = Foam Concrete, International Journal of Civil Engineering and Technology, 4(4), 2013, pp [13] IS: Methods of tests for strength of concrete, New Delhi, India: Bureau of Indian Standards editor@iaeme.com