Study On Bending Fatigue Properties Of Rubber Concrete

Ordinary cement concrete pavement has high rigidity and high brittleness.It is prone to produce the crack under the alternating load of vehicles,resulting in a reduction of service life.Once local damage occurs,the repair will be very difficult.A lot of research shows that the use of waste tire rubber particles on cement concrete pavement can not only solve the environmental pollution problems,but also improve the performance of concrete pavement in crack resistance,frost resistance,vibration reduction and noise reduction.Based on the current problem of low fatigue life of cement concrete pavement,this paper studies the improvement degree of anti-fatigue performance of rubber concrete.The main research work is as follows:(1)The optimal particle size of the rubber aggregate is preferred.Using C30 as the reference concrete,mixing the rubber particles with the particle size of 10 mesh,30 mesh,50 mesh,and the amount of 5%,10%,15% and 20% respectively.Then the rubber concrete specimens were casted to conduct the cube compressive strength,splitting tensile strength and flexural strength tests.The comparative test results show that,the rubber concrete with 30 meshes has the best performance.So the optimal particle size of the rubber particles is 30 meshes.(2)The constitutive relationship between the axial compression and the axial tension of rubber concrete was studied.The rubber particles of 30 meshes are mixed into the concrete in different amounts to carry out the axial compression tests and the axial tensile tests.The compressive stress-strain curves and tensile stress-strain curves are measured,and the axial compressive and the axial constitutive equations were established.Then the elastic modulus and Poisson’s ratio are calculated to provide a basis for finite element analysis.(3)Experimental research and numerical simulation of rubber concrete bending performance.A four-point bending static load test and ABAQUS static load simulation were carried out to obtain the ultimate load,peak deflection and load-deflection curve.The flexural performance of rubber concrete and ordinary concrete were compare.And the ABAQUS stress ODB result to prepare for the research of bending fatigue performance.(4)Fe-safe analysis of concrete bending fatigue life under constant and variable amplitude loading.The stress cloud image obtained by the finite element simulation of ABAQUS bending static load was imported into the fatigue software Fe-safe.Then,the fatigue parameters and load spectrum were entered to calculate the fatigue life of rubber concrete under the constant amplitude and variable amplitude loading methods,and under different stress levels.As a result,comparative analysis with ordinary concrete and rubber concrete was obtained.The results show that,whether ordinary concrete or rubber concrete,under equal amplitude cyclic loading,the higher the stress level,the lower the fatigue life.The fatigue life of rubber concrete at each dosage is greater than that of ordinary concrete.And the fatigue life increases with the increase of the rubber content.Under the effect of variable amplitude load,the fatigue life of concrete increases with the amount of rubber particle increases.As the level of variable amplitude increases,the fatigue life of rubber concrete decreases.Comparing with the fatigue life of concrete under constant amplitude cyclic load,whether or not rubber powder was added,the fatigue life of concrete was reduced,and the more the amplitude level,the lower the fatigue life under variable amplitude cyclic load.