Experimental Study on Properties of No-fine Concrete

Transcription

1 Research Paper Volume 2 Issue 10 June 2015 International Journal of Informative & Futuristic Research ISSN (Online): Experimental Study on Properties of No-fine Paper ID IJIFR/ V2/ E10/ 055 Page No Subject Area Key Words No-Fine, Porosity, Compressive Strength, Aggregate Size Civil Engineering Received On Reviewed On Published On Md. Abid Alam 1 Shagufta Naz 2 Assistant Professor, Department of Civil Engineering, Integral University, Lucknow-Uttar Pradesh M.E. Student Department of Civil Engineering, Integral University, Lucknow-Uttar Pradesh Abstract No-fine concrete has been in use in many countries over more than a century. Its higher porosity helps in percolating rain water directly to ground and thereby helps in recharging groundwater aquifer. In this study, 3 batches of no-fine concrete each with two different sizes of aggregate were prepared to find the mix that generated high compressive strength and study the effect of percentage of fine aggregate on the compressive strength of no-fine concrete. The purpose of this project is to analyze the feasibility of producing highly sustainable no-fine concrete mixtures and evaluating the effect of fine aggregate on their properties. No-fine concrete is produced by using ordinary Portland cement, coarse aggregates, and water. This concrete is tested for its properties, such as slump value, porosity and compressive strength. However 10 to 20% fine aggregate is used to partially replace coarse aggregate. The results showed that porosity has significant effect on compressive strength of no-fine concrete. Replacement of coarse aggregate with fine aggregate up to 20% had significant effect on the porosity and compressive strength of the no-fine concrete. 1. Introduction Today in the present world we are very much fond of sustainable and eco-friendly means of construction. Particularly in a country like India where flooding and waterlogging problems are the major environmental issues sustainable development has become a necessity. Various sustainable Copyright IJIFR

2 and eco-friendly means are being implemented to tackle these problems where No-fine concrete pavement is one among them. Working on rain-drain concept No-fine concrete allows a significant amount of storm water to seep into the ground, thereby recharging the groundwater and reducing the storm water runoff. No-Fines is a light-weight concrete produced by omitting the fines from conventional concrete. No-fines concrete (sometimes referred to as porous or open-textured concrete) is a concrete consisting of cement, coarse aggregate and water. It has its origin in late 1940s and now been widely used in United States, Japan and Europe because of its various environmental benefits such as controlling storm water runoff, restoring groundwater supplies and reducing water and soil pollution. Apart from this it has the potential to reduce urban heat island effects and can be used to reduce acoustic noise in roads. No-fines concrete is generally made with aggregate/binder ratio of 6 : 1 to 10 : 1. Coarse aggregates used are normally of size passing through 20 mm and retained on 10 mm. The water/cement ratio for satisfactory consistency varies between a narrow range of 0.27 and The 28-days compressive strength ranges from 5.6 to 21.0 Mpa, with porosity ranging from 14 to 31%, and permeability coefficient varies from 0.25 to 6.1 mm/s (Schaefer et al. 2006). The effects of aggregate-cement ratio, aggregate sizes and type of binder material on strength of No-fine concrete have been reported in the past (Tennis et al. 2004; Malhotra 1976; Meininger 1988; Otani et al. 2005). Pioneering research on No-fine concrete has been carried out worldwide for the past few decades to make it suitable for major pavement application works. This paper discusses the results of an experimental study on No-fine concrete by varying two different sizes of coarse aggregate, along with the variation of 0, 10 and 20% fines. The investigated properties are slump, porosity and 28-days compressive strength. The results obtained are used to develop interrelationship among porosity and compressive strength for two different sizes of coarse aggregate. 2. Experimental Programme 2.1 Materials Ordinary Portland cement of 53 grade was used throughout the experimental investigation conforming to recommendations stated in IS 4031(1999). The normal consistency and initial setting time of cement was 29% and 32 minutes respectively. Locally available coarse sand was used as fine aggregate. The test procedures as mentioned in IS-383(1970) were followed to determine the physical properties of fine aggregate as shown in Table 1. Two single sized crushed stone aggregates ranging from 12.5 mm to 2.36 mm and 20 mm to 6.3 mm (10mm and 20mm sizes) were used in nofine concrete mixes. The tests carried out conform to IS-383: (1970) as tabulated in Table 2. As per recommendation of IS: 456 (2000), the water to be used for mixing and curing of concrete should be free from deleterious materials. Therefore potable water was used in the present study in all operations demanding control over water quality. Table 1: Physical Properties of fine aggregate Physical Properties Observed values Recommended values Grading Zone 1 - Fineness modulus Specific Gravity

3 Table 2: Physical Properties of coarse aggregate Physical Properties Observed values Recommended values 10mm aggregate 20mm aggregate Fineness Modulus Aggregate crushing value (%) Not more than 45% Aggregate impact value (%) Not more than 45% 2.2 Methodology The mix proportioning procedure for No-fine concrete was done according to Guide for selecting proportions for no slump concrete reported by ACI committee 211.3R-02.The method is based on the volume of paste necessary to bind the aggregate particles together while maintaining the necessary void content. Once the paste volume is determined and the desired w/cm is selected, the cement and water quantities can be calculated. When fine aggregate is used, the paste volume should be reduced by 2% for each 10% fine aggregate of the total aggregate for well-compacted No-fine concrete, and by 1% for each 10% fine aggregate of the total aggregate for lightly compacted Nofine concrete. These reductions are necessary to maintain the same percent voids by volume. 2.3 Mix Proportioning The basic mix proportion for no-fine concrete is binder materials, coarse aggregate and water: 1.0:7.0:0.35 respectively. Mix 1 contained 100% Portland cement. Mix 2 had 90% of the Portland cement and 10% fine aggregate by weight. Mix 3 had 80% of the Portland cement and 20% fine aggregate by weight. Three Control mixes corresponding to two aggregate sizes are proportioned by the absolute volume method. A total of 6 mixes were studied. Water/binder ratio of 0.35 and theoretical void content of 20% was used for all no-fine concrete mixes. Details of these mixes are presented in Tables 3. Mix No. W/C Cement (Kg/M 3 ) Table 3: Mix details of No-Fine concrete Fine Aggregate Water Content(Kg/M 3 ) Coarse Aggregate % Kg/m 3 % Kg/m 3 M M M M M M Mixing of, Casting and Curing of test Specimens Mixing was done by machine mixing. Initially the dry mix constituents of the mix namely cement, fine aggregate and coarse aggregate was mixed for two minutes in the mixer and then the water were added and mixing continued for another 2 minutes. The total mixing time was kept at 4 minutes until 3689

4 a homogeneous mixture was obtained. Compaction was achieved by hand using the standard tamping rod ensuring the filling of the mould in layers with appropriate blows and also ensuring the same method followed for all the mixes. All specimens were de molded after 24 hours and stored in water until the age of testing. 2.5 Test methods Fresh No-fine concretes were tested for slump which is a quick measure of workability. However the hardened concrete was tested for porosity and compressive strength discussed below Slump Test The slump test was done in accordance with the IS As the No-fine concrete falls under the category of no slump concrete therefore it shows poor workability. However the slump of the No-fine concrete has no correlation with its workability Porosity Test The porosity of the hardened concrete was calculated from the oven-dry and saturated Weights, using the following equation based on earlier study (Park and Tia 2004). ( ) Where, P = porosity (%) W1 = weight under water W2 = oven dry weight Vol. = volume of sample, = density of water (a) Oven dried weight (b)weight under water Figure 2 (a, b): Porosity test Compressive Strength Test Compressive strength test was performed according to ASTM C 39. Cubes of specimen of size 150 mm x 150 mm x 150 mm were prepared for each mix. After 24 hours the specimens were demoulded and cured in water for 28 days until testing. For specimens with uneven surfaces, capping was used to minimize the effect of stress concentration. The compressive strength reported is the average of three results obtained from three identical cubes. 3690

5 3. Results And Discussion Table 4 shows the porosity and compressive strength for all the six concrete mixes. The porosity varies as the aggregate size increases but shows a decreasing trend when some fines were added to it. The concrete has zero slump value as the concrete completely collapse when the mould of frustum of cone is raised vertically. Similar variations in concrete strength were obtained when tested after 28- days. Table 4 : Porosity and Compressive strength of No-fine concrete Mix Porosity range (%) Compressive strength Mean porosity Mean strength (Mpa) No. (Mpa) (%) M M M M M M Effect of aggregate size and percentage of fines on slump value of concrete The result shows that No-fine concrete has zero slump value as the concrete completely collapse when the mould of frustum of cone is raised vertically. However the addition of 10% and 20% fine aggregate has no significant improvement in the slump value. The slump value shows the similar result when no-fine concrete is casted with 20 mm size coarse aggregate. 3.2 Effect of aggregate size and percentage of fines on porosity of concrete The porosity of No-fine concrete (Mix 1 & Mix 4) is and 0.35 which is the highest among the no-fine concrete having two different aggregate sizes. No-fine concrete with 10% fines (Mix 2 & Mix 5) had the porosity of 0.24 and 0.28, while concrete with 20% fines (Mix 3 & Mix 6) showed the porosity of 0.18 and For the No-fine concrete with 0% fine aggregate, the porosity is affected by aggregate sizes. With increase in %age of fine aggregate the porosity of No-fine concrete decreases. Similar trend of result were obtained for no-fine concrete with 20 mm size aggregate. Fig. 3 shows the effect of fine aggregate on porosity of no-fine concrete. Figure 3: Effect of % age of fine aggregate on porosity on No-fine concrete 3691

6 3.3 Effect of aggregate size and percentage of fines on compressive strength of concrete Compressive strength for all no-fine concrete mixes increases with the increase in fine aggregate content. The compressive strength of no-fine concrete also varies with the size of coarse aggregate in the concrete mixes. Fig. 4 shows the effect of aggregate size and percentage of fine aggregate on compressive strength of No-fine concrete. Figure 4: Effect of %age of fine aggregate on compressive strength of No-fine concrete 3.4 Relationship between porosity and compressive strength of No-fine Figure 5 and 6 shows the relationship between porosity and compressive strength for all no-fine concrete mixes. The result shows that with increase in the porosity there is corresponding decreases in the compressive strength. Thus porosity of No-fine concrete affects the compressive strength. With the addition of percentage fine aggregate in the mix, porosity decreases and thus the strength is increased. The following empirical equations for 28-day compressive strength are obtained for nofine concrete with 10 mm and 20 mm aggregates. These equations could be used for the mix design of no-fine concrete. The correlation coefficient for these two equations was 0.99 and 0.96, indicating a high degree of correlation between compressive strength and porosity depending on the size of aggregate. Where (For 10 mm coarse aggregate) (For 20 mm coarse aggregate) = 28-day compressive strength (MPa) P = the porosity of the pervious concrete mix (%) 3692

7 Figure 5: Relationship between porosity and compressive strength of no-fine concrete However a general relationship between porosity and compressive strength was obtained by combining the results of all 6 mixes of no-fine concrete regardless of the coarse aggregate size. Following empirical equation was obtained for No-fine concrete. Where = 28-day compressive strength (MPa) P = the porosity of the pervious concrete mix (%). Figure 6: Relationship between porosity and compressive strength of all in aggregate no-fine concrete 3693

8 4. Conclusions Based on the experimental study on no-fine concrete, the following conclusions could be made: I. The slump of No-fine concrete is found to be zero irrespective of aggregate size and addition of fine aggregate. II. The porosity of No-fine concrete is largely affected by the size of coarse aggregate used in concrete mix. mix containing 20 mm size aggregate shows higher porosity in comparison to concrete mix containing 10 mm size aggregate. The addition of fine aggregate to concrete mix lower the porosity because this fills the void spaces between the aggregate resulting in decreased porosity. III. The compressive strength of No-fine concrete largely depends upon the size of coarse aggregate used in the concrete mix and the percentage of fine aggregate used in the mix. Lower value of compressive strength was obtained for 20 mm size aggregate mix. However the inclusion of fine aggregate results in comparatively good strength. The relationship between compressive strength ( ) and porosity (P) are given by the following empirical equations: For 10 mm aggregate No-fine concrete: For 20 mm aggregate No-fine concrete: For all-in aggregate No-fine concrete: References [1] Malhotra, V.M. (1976). No- fines concrete-its properties and applications. Journal of the American concrete institute,73(11), [2] Meininger, R.C. (1988). No-fines pervious concrete for paving. concrete international,10(8), [3] Tennis.Paul.D, Michael L. Leming, David J. Akers, (2004). Pervious concrete pavements, special publication by Portland cement association and The National Ready Mixed Association,USA,2004. [4] Park, S. and M. Tia. (2004). An experimental study on the water-purification properties of porous concrete. Cement and Research 34, pp [5] Otani, T., Sato, Y., Kiyohara, C., Murakami, M., & Mitsui, Y.(2005). An equation for predicting the compressive strength of porous concrete. Journal of Structural and Construction Engineering, 590, [6] Schaefer, V. R., Wang, K., Suleiman, M. T., & Kevern, J. T. (2006). Mix design development for pervious concrete in cold weather climates, Final Report, center for transportation research and education, Iowa State University, February 2006, 85p. [7] ACI Committee 522, (2006).Pervious concrete. Report No.522R-06, American concrete institute.detroit,usa,2006,25p. [8] Aoki, Y., Sriravindrarajah, R., & Khabbaz, H. (2008). Environmentally friendly sustainable pervious concrete. In Proceedings of the 20th Australasian conference on the mechanics of structures and materials, Toowoomba, Australia, December [9] Sriravindrajah.R, Wang.N.D.H and Ervin.L.J.W et al. (2012). Mix design for pervious recycled aggregate concrete. International Journal of concrete structures and materials, volume-6, Number- 4,pgs ,December [10] Alam M.A (2014) Experimental investigation on pervious concrete for sustainablae development. M.Tech Dissertation Z.H college of Engg. & Tech. A.M.U Aligarh