Experimental Study On Fracture Property Of Steel Fiber-reinforced Rubberized Concrete

In this paper,a new type of environmental friendly high-performance composite concrete material—steel fiber reinforced rubberized concrete(SFRRC)was studied.Mixing rubber particles which are made of the crushing waste tire into concrete can reduce the rubber tyre pollution and improve concrete fracture toughness,impact resistance,fatigue resistance,but can not get rid of the disadvantage of low flexural strength and tensile strength.Incorporation of steel fibers can play its enhancements on toughness,tensile and flexural characteristics,solves the issues of decline of concrete basic mechanical properties causing by the mixing of rubber.While both can play a synergistic effect,thereby obtaining a new high-performance green concrete material with excellent mechanical properties,which has high significance and application prospects.Based on the ordinary concrete,the steel fiber content(0.5%,0.75%,1%)and rubber replacement rate(5%,10%,15%)were used as the variables to modify the properties of ordinary concrete.Through the basic mechanical test,SEM test and three point bending fracture test,the author focused on studying the basic mechanical properties and fracture properties of SFRRC.The main research work has been done as follows:(1)30 groups of 90 specimens with the dimension of100mm×100mm×100mm and 18 groups of 54 specimens with the dimension of 100mm×100mm×400mm were made,and the compressive resistance strength,split-tensile strength and bending strength test were given at different ages and with different fibers content.According to the test result,the steel fiber's effects of this test on mechanical properties of concrete were analyzed.(2)16 groups of 48 specimens with the dimension of150mm×150mm×150mm,8 groups of 24 specimens with the dimension of 100mm×100mm×400mm and 5 groups of 30 cylinder specimens with the dimension of ?150mm×300mm were made,and the mechanical properties test and SEM test of SFRRC were carried out.The influence of different fibers content and different rubber replacement rate on SFRRC's basic mechanical properties were studied,which has been given a microcosmic explanation by observing the interfacial transition zone(ITZ)between steel fiber,rubber particle and hardened cement paste(HCP).(3)9 groups of 27 pre-cracked beams with the dimension of100mm×100mm×400mm were made,and the fracture properties of SFRRC were carried out.In this test,the three-point bending notched beam's load-deflection(P-?)curves and load-crack mouth opening displacement(P-CMOD)curves were measured,double-K fracture parameters of SFRRC are calculated.According to the comparison which was with different steel fibers content and different rubber replacement rate,the effects of steel fibers and rubber particles are researched on SFRRC's fracture properties,the fitting formula of double-K fracture parameters development at different ages was measured.