Experimental Research On Mechanical Properties Of Waste Steel Fiber Rubber Modified Recycled Aggregate Concrete

The steel fiber rubber particles, from smashed waste rubber tire, join to Recycled Aggregate Concrete (RAC)can solve the problems both environmental pollution and resource shortage. At the same time, the rubber particles can improve the ductility of RAC, steel fiber can develop the function of in cracking resistance, reinforcing strength and reinforcing toughness on the RAC, the Waste Steel Fiber Rubber modified Recycled Aggregate Concrete (WSR-RAC) has widespread use prospect.This paper is based on RCA, adding rubber or waste steel fiber rubber or original steel fiber rubber to RAC, with two dominant parameters both the replacement rate of recycled coarse aggregate (30%,60%) and admixture's content (0%,2%,5%,8%,11%) as variables, to study the basic mechanical properties of modified RAC by comparative text in three types modified RAC. Making a total of 27 groups 162 150mm×150mm×150mm cubes for cube compressive strength and splitting tensile tests and the text were carried out; also making a total of 27 groups 81Φ150mm×300mm cylinders for axial compressive test and the text were carried out. The main work includes the following four aspects:(1) The mix ratio of RAC was determined and the performance of new mix-concrete was tested. The density change of three types modified RAC which conserved after 28 days were analyzed;(2) The cubic compressive performance of three types modified RAC were researched. The effects of recycled coarse aggregate with different replacement rate and different admixture with different content were investigated on basic mechanical properties and failure characteristics of RAC, and the contrast of three types modified RACrs compressive performance were analyzed;(3) The tensile properties of three types modified RAC were researched. The effects of recycled coarse aggregate with different replacement rate and different admixture with different content were investigated on tensile splitting strength, failure characteristics and the ratio of tensile-compressive strength and compressive-strength of RAC, and also the contrast of three types modified RAC's tensile properties were analyzed; at the same time the conversion relations between splitting tensile strength and cube compressive strength of RAC were established.(4) The cylinder axial compressive performance of three types modified RAC were researched and the stress-strain curve of three types modified RAC were obtained. And also the effects of recycled coarse aggregate with different replacement rate and different admixture with different content were investigated on modified RAC's axial compressive strength, elastic modulus, peak strain and ultimate strain. The normalization stress-strain full curves of three types modified RAC were fit by using nonlinear regression's method and the relationship between the parameters in the curve equation under different replacement rate of recycled coarse aggregate and different admixture with different content were determined.