Effect of Used Tire Rubber Powder Addition as Eco-concrete Innovation Through Job Mix Formula on Compressive Strength and Modulus Elasticity of Concrete

Abstract

This article discusses the effect of adding used tire rubber powder as an admixture of fine aggregate using the design method of job mix formula K-250 according to SNI 03-2834-2000. The variation of adding used tire rubber powder is 0%, 2.5%, 5%, 7.5%, and 10% against the acceptable aggregate content weight ratio. The Fas used was 0.58 with 210 l/m³ water. The test methods used are inspection of concrete constituent materials, vicat test, slump test, compressive strength, and modulus of elasticity of concrete. From testing the slump test, compressive strength, and elastic modulus of 28-day-old concrete, the more the level of addition of used tire rubber powder, the value of slump, compressive strength, and modulus of elasticity of concrete decreases. Seen at an average compressive strength of 21.06 MPa has an elastic modulus value of 21564.02 MPa, while at an average compressive strength of 15.13 MPa, the average elastic modulus value is 18268.14 MPa. Both data show that regular concrete is plastic and concrete with an admixture of used tire rubber powder is elastic. The compressive strength value decreased proportionally to the used tire rubber powder addition level, with a percentage decrease of 28% from standard concrete. The theoretical modulus of elasticity decreased by 15% from regular concrete, and the experimental modulus of elasticity increased by 3%. From the stress-strain relationship graph, concrete with used tire rubber powder experienced an increase in strain value of 171% of regular concrete when subjected to a load of 140 kN. The strain value illustrates the elasticity of concrete, where the more significant the strain value in concrete, the more elastic the concrete. It is concluded that concrete with used tire rubber powder is elastic, and regular concrete is plastic. The elasticity of concrete affects the resistance of deformation when damage occurs, so concrete with used tire rubber powder can minimize structural damage because it is more elastic.