Engineering Properties of Concrete Containing Recycled Tire Rubber

Transcription

1 ICCBT2008 Engineering Properties of Concrete Containing Recycled Tire Rubber N. J. Azmi *, Universiti Tenaga Nasional, MALAYSIA B. S. Mohammed, Universiti Tenaga Nasional, MALAYSIA H. M. A. Al-Mattarneh, Universiti Tenaga Nasional, MALAYSIA ABSTRACT The test program was carried out to develop information about the mechanical properties of rubberized concretes. A control Portland cement concrete mix (PCC) is designed using American Concrete Institute mix design methods and crumb rubber contents of 10, 15, 20 and 30% by volume were chosen by partially replacing the fine aggregate with crumb rubber. Totally 15 concrete mixes with three different water cement ratio (0.41, 0.57 and 0.68) were cast and tested for compressive strength, splitting tensile strength, flexural strength and modulus elasticity. The results revealed that although there is a reduction in strength for crumb rubber mixture, but slump values increase as the crumb rubber content increase from 0% to 30%. Meaning that crumb rubber mixture is more workable compare to normal concrete and can be acceptable to produce crumb rubber concretes. The results also indicated that inclusion crumb rubber in concrete reduced the static modulus elasticity. Although there is a reduction in modulus elasticity but the deformability crumb rubber concrete increasing compared to normal concrete. Keywords: crumb rubber, recycled tire, concrete, compressive strength *Correspondence Author: Dr Bashar S. Mohammed, university Tenaga Nasional, Malaysia. Tel: , Fax: bashar@uniten.edu.my

2 Engineering Properties of Concrete Containing Recycled Tire Rubber 1. INTRODUCTION Utilization of industrial waste products in concrete has attracted attention all around the world due to the rise of environmental consciousness. Accumulations of stockpiles of tires are dangerous because they pose a potential environmental concern, fire hazards and provide breeding grounds for mosquitoes that may carry disease (1). Tire pile fires have been an even greater environmental problem. Tire pile fires can burn for months, sending up an acrid black plume that can be seen for dozens of miles (1). That plume contains toxic chemicals and air pollutants, just as toxic chemicals are released into surrounding water supplies by oily runoff from tire fires (1). In order to prevent the environmental problem from growing, recycling tire is an innovative idea or way in this case. Recycling tire is the processes of recycling vehicles tires that are no longer suitable for use on vehicles due to wear or irreparable damage (such as punctures). The cracker mill process tears apart or reduces the size of tire rubber by passing the material between rotating corrugated steel drums (2).By this process an irregularly shaped torn particles having large surface area are produced and this particles are commonly known as crumb rubber (2). A review of the literature revealed that several investigations into rubber concrete have been previously performed. Fattuhi et al. (3) mentioned in his report that the concrete made with low grade rubber concrete had lower compressive strength compared with high grade rubber concrete. These similar observations were also made by Topcu at al (4) and this could be caused by weak interfacial bonds between the cement paste and tire rubber. Tarun et al. (2) have reported that the compressive strength of rubberized concrete can be improve when fine aggregate was fully replaced by fine crumb rubber. He also indicated that if the rubber particles have rougher surface or given a pretreatment, the better and improved bonding may develop with the surrounding matrix, and that may result in higher compressive strength. Piti el al (5) outlined that crumb rubber responses were found to denote greater flexibility and toughness with larger deflection at peak load, longer post-peak load responses and higher fracture energy. This paper presents data on the mechanical properties of concrete incorporating crumb rubber. These data were compared to those of the control concrete mixes, which was prepared separately. The strength parameters investigated included; the compressive strength, flexural, splitting tensile strength of the concretes and the modulus of elasticity. 2. EXPERIMENTAL DETAILS 2.1 Materials Portland Cement Ordinary Portland cement (OPC), which conforms to ASTM Type 1, was used (6) Crumb rubber The crumb rubber used was processing with a granulator and/or cracker mill and having a mm nominal maximum size. 374

3 N. J. Azmi and B. S. Mohammed Aggregates Coarse aggregate from a local commercial quarry with a maximum nominal size of 10 mm was used. The fine aggregate used was natural river sand having a 2.36 mm nominal maximum size. The results of physical properties of crumb rubber, fine aggregate and coarse aggregate are shown in Table 1. Table 1. Physical properties of aggregates Property Fine Coarse Crumb aggregate aggregate rubber Specific gravity Fineness modulus Water absorption (%) Mix proportion Concrete mix proportions used are shown in Table 2. A control Portland cement concrete mix (PCC) is designed using American Concrete Institute mix design method (7). Water content was kept constant at 243 kg/m³ of concrete and the design slump mm was selected for all control mixes. The parameters examined were water to cement ratio and crumb rubber content.these parameter were related to the following variables : crumb rubber content of 10%, 15%, 20%, and 30% by volume of the total fine aggregate has been used to replace fine aggregate in the mixtures and w/c ratios of 0.41,0.57 and Each of the water cement ratio mixture has attained a different values target of 28 days compressive strength of 40, 30 and 20 MPa for water to cement ratio of 0.41, 0.57 and Table 2. Mix proportion for a cubic meter of concrete crumb rubber Cement fine aggregate coarse aggregate water w/c % kg/m³ kg/m³ kg/m³ kg/m³ kg/m³ % % % % % % % % % % % % % % %

4 Engineering Properties of Concrete Containing Recycled Tire Rubber 2.3 Preparation and casting of specimens The total mixes that need to be prepared in this study is about 15 mixing and this included a preparation of 90 cubes samples (100X100X100) mm for compressive strength test, 135 samples of beam (100X100X500) mm for flexural test, 180 samples of cylinders (150 diameter X 300 height) mm for splitting tensile test and modulus elasticity test. All the samples have been prepared for conventional concrete and replacement fine aggregate with crumb rubber for 10%, 15%, 20%, and 30%. The samples were categorized by age of the concrete at the day of testing and the rubber content. For each percent rubber content (10%, 15%, 20%, and 30%), 3 cubes were tested for compressive strength after 7 and 28 days immersed in the water, 3 samples of cylinders were used to test splitting tensile at age 28 days and modulus elasticity at age 28 and 90 days. The 3 samples of beam were tested on flexural strength test at age 7, 14 and 28 days of curing. 3. RESULT AND DISCUSSION 3.1 Properties of Fresh Concrete The results for slump values are given in Figure 1. The results show that the workability of the Portland cement concrete can be improved when adding the crumb rubber content. The mix design for water cement ratio 0.68 gave the highest workability compared to others mix design. The slump value increased approximately about 10% as the crumb rubber content increased from 0% to 30%. Meaning, the crumb rubber concrete specimens have acceptable workability in terms of ease of handling, placement, and finishing. In the current study, the balling effect during the mixing is reported especially when incorporating with 30% replacement of crumb rubber. This is due to the interlocking actions of the wires was apparent before the mixing process. Even though the balling effects the mixing but the mix remained workable (8). Figure 1. The workability of concrete mixes for water cement ratio 0.41, 0.57 and

5 N. J. Azmi and B. S. Mohammed 3.2 Compressive Strength The compressive tests were tested at the ages of 7 and 28 days. The results are shown in Figure 2, 3 and 4. Each value on the bar chart is the average of at least three cube specimens. It is observed that there was a reduction approximately 35% in compressive values when fine aggregate replaced with crumb rubber compared with control mix. This is due to compressive strength Portland cement control mix is dependent greatly on the coarse aggregate, density, size and hardness. Because the fine aggregate was partially replaced by crumb rubber, the reduction in strength is anticipated. Based on the result, the maximum compressive strength value for crumb rubber concrete increased from age 7 to age 28 day, decreased with increasing water cement ratio from 0.41 to 0.68 and decreased with increasing the amount of crumb rubber from 0% to 30%. Even though there was a reduction in compressive strength value but the observation shown that the crumb rubber concrete remained an acceptable workability. Figure 2. Compressive strengths development of concrete mixes at different testing ages for w/c= 0.41 Figure 3. compressive strengths development of concrete mixes at different testing ages for w/c =

6 Engineering Properties of Concrete Containing Recycled Tire Rubber Figure 4. Compressive strengths development of concrete mixes at different testing ages for w/c= Flexural strength The compressive tests were tested at the ages of 7 and 28 days. The results are shown in Figure 5, 6 and 7. Each value on the bar chart is the average of three prismatic specimens. It is shown that the flexural strength decreased with the increased of the crumb rubber content from 0% to 30% in a fashion similar to that observed in the compressive strength. However the reduction in compressive strength was significantly higher than that in flexural strength. The mix design for w/c ratio 0.41 show the highest loss in flexural strength approximately about 20% compared with w/c ratio 0.57 and 0.68 which only loss approximately about 5% to 8% for w/c 0.57 and 0.68 respectively. Figure 5. Flexural strength development of concrete mixes at different testing ages for w/c =

7 N. J. Azmi and B. S. Mohammed Figure 6. Flexural strength development of concrete mixes at different testing ages for w/c = 0.57 Figure 7. Flexural strength development of concrete mixes at different testing ages for w/c = Splitting Tensile strength The splitting tensile strength tests were tested at the ages of 28 days. The results are shown in Figure 8.There was a reduction approximately about 15% in splitting tensile value when crumb rubber content increased from 0% to 30%. The reduction in splitting tensile strength can be attributed to the existence of rubber particles. This phenomena can be explained by the non polarity of the rubber attracts air to its surface and therefore reduces the bong with cementitious matrix (8). It was observed that it was hard to separate the failed specimen with crumb rubber content because the crumb rubber were bridging the gap and keeping the two concrete parts together especially for the mix design with 30% replacement. 379

8 Engineering Properties of Concrete Containing Recycled Tire Rubber Figure 8. Splitting Tensile strengths development of concrete mixes for water cement ratio 0.41,0.57 and 0.68 at age 28 day 3.5 Modulus Elasticity The modulus elasticity tests were tested at the ages 28 days. The results are shown in Figure 9. There was a reduction approximately about 30% in modulus elasticity value when crumb rubber content increased from 0% to 30%. The inclusion of crumb rubber implies defects in the internal structure of the composite material, producing a reduction of strength and decrease in stiffness. The observation shown that there was a large displacement and deformation due to the fact that crumb rubber has an ability to withstand large deformation. This can be explained by the behavior of the crumb rubber particles inside the mix; these particles seem act as spring and caused a delay in widening the cracks and preventing the catastrophic failure which is usually experienced in normal concrete specimens (4). Figure 9. Modulus Elasticity development of concrete mixes for water cement ratio 0.41, 0.57 and 0.68 at age 28 day 380

9 N. J. Azmi and B. S. Mohammed 4. CONCLUSION The results indicated that there was an increasing in slump value when crumb rubber content increased from 0% to 30%. Meaning that the workability of crumb rubber concrete exhibits an acceptable in term of ease of handling, placement and finishing with respect to normal concrete. Although the strength data developed in this study (compressive strength and flexural) and others (splitting tensile test) indicated a systematic reduction in strength with the increased of crumb rubber content but the crumb rubber concrete mixes remained an acceptable workability. The static modulus elasticity of crumb rubber concrete was lower than normal concrete but there was a large displacement and deformation due to the fact that crumb rubber aggregate has an ability to withstand large deformation. Acknowledgement A special thank you to The Ministry of Science, Technology and Innovation (MOSTI) of Malaysia for granting this project under code SF0091. REFERENCE [1]. TIA supports the tire and rubber recycling market through its Tire and Rubber Recycling Advisory Council (TRRAC ). [2]. Tarun R. Naik Properties of concrete containing scrap tire rubber-an overview. Department Of Civil Engineering and Mechanics College of Engineering and Applied Science, The University of Wisconsin-Milwaukee [3]. Fattuhi n, Clark L. Cement based materials containing shredded scrap truck tire rubber. Construction building Mater 1996; 10 (4): [4]. Topcu, I.B., The properties of rubberized concrete, Cement and concrete Research, vol. 25, No. 2, 1995 [5]. Piti Sukontasukkul Properties of concrete pedestrian block mixed with crumb rubber. Department of Civil Engineering, King Mongkut s Institute of Technology North Bangkok: [6]. ASTM C Standard Specification for Portland cement. [7]. American Concrete Institute Standard , standard practice for selecting proportion for normal, heavyweight and mass concretes. [8]. Christos G. Papakonstantinou Use of waste steel beads in Portland Cement Concrete department of civil and environmental engineering, university of Massachusetts Dartmouth, Cement and Concrete Research. 381