Effect of crumb rubber particle size on the properties of concrete

Abstract

There are billions of old waste tires accumulating every year in both developedanddevelopingcountries.Such a large amount of waste tires needs to be properly disposed of to avoid harming the environment or endangering public health.Utilizing such trash in the production of concrete is a smart and eco-friendly way to deal with this problem. This study looks into the possibility of taking those old tires and using them to replace some of the fine aggregate,such as sand, and coarse aggregate,such as stone, we normally put in concrete. Over the past couple of decades, extensive study has been done on the substitution of aggregate in non-structural rubberized concrete with rubber particles. In more recent years,theeffectofrubberparticlesizestomakerubberized concrete replacing mineral aggregates and their potential for structural application has gain popularity for investigation. In this study, an experimental investigation was done to observe how replacing of fine and coarse aggregates by rubberparticles with varying percentages would affect themechanical and fresh characteristics of concrete by casting and testing 100mm by 200mm concrete cylinders. In this investigation, fourdifferent particlesizes of crumb rubber (CR) wereused such asCR-A (from #8 to #30 mesh), CR-B (from #4 to #8 mesh), CR-C (from #4 to #30 mesh), and CR-D (from 9.5 mm to 19 mm). CR-A, CR-B, and CR-C were usedas a partialreplacement ofsand and CR-D was used in place of stone inthe concrete mix as coarse aggregate at 0%, 5%, 10%, and 15%. Slump, compressive strength, spiltting tensile strength, modulus of elasticity, Poisson’s ratio, ductility, and toughness were evaluated for rubberized concrete and then compared to conventional concrete to understand the behavior of rubberized concrete. According to the tests result, workability, compressive strength, modulus of elasticity, and splitting tensile strength decreased as the amount of rubber particles, both fine and coarse rubber particles increased. Whereas Poisson’s ratio, ductility and toughness were improved significantly. Though splitting tensile strength was found decreased compared to NC, a greater value was observed for 10% replacement in comparison with 5% replacement of sand. It was found from the experimental results that, sand replacement by CR-A, CR-B, and CR-C has better strength compared to stone replacement by CR-D. Among the three fine particles of CR, CR-B showed greater strength in terms of compressive strength, splitting tensile strength, Poisson’s ratio, ductility, and toughness for all percentages of replacement. The ductility of concrete was improved up to 35% and toughness was improved up to 71% compare to NC for up to 15% of CR. The particle size CR-B showed greater improvement in comparison with other sizes of CR. The reduction of compressive strength for CR-B was less than other sizes (9%, 14.5%, and 21.4%) for 5% to 15% replacement of sand. Based on the experimental results, it is suggested that a 5% content of CR-Bcan be utilized in concrete structures, as it showed better strength compared to other CR particles. The material properties of CRC found in the experimental test were then used to calibrate the concrete damage plasticity (CDP) model in FEA by ABAQUS software. The selected CR size and replacement ratio from experimental test was then used to observe the behaviour of CRC members like column and beam with reinforcement. Finite element models of column and beam were validated against experimental results found in literatures. Then the validated models were used for parametric study where six column sectionsand six beam sections of different cross-sectional dimension and reinforcement ratiowere analyzed. From the FEA, it was observed that the capacity of CRC columns with 5% CR-B was less than the NC column but the ductility of CRC columns improved significantly. However, load deformation behaviour of CRC beams with 5% CR-B was found almost similar to NC beams. Therefore, it can be stated that CRC with a 5% CR-B may be used in structures where ductility is essential.