Study On Mechanical Properties And Damage Characteristics Of Rubber Concrete Under Cyclic Loading

In order to enhance the utilization rate of waste rubber in the sustainable development of ecological environment and analyze the application feasibility of rubber concrete in road engineering,the internal damage characteristics of rubber concrete under cyclic loading are studied in the paper.The rubber particles with particle size of 0.85mm,1-3mm and 3-6mm were mixed into concrete materials by replacing sand with 10%of the mass of cementitious materials.The damage characteristics of these three groups of rubber concrete and a group of ordinary concrete were analyzed,and the optimal particle size of rubber particles was obtained.In this paper,the mechanical properties and damage characteristics of rubber concrete(RC)under cyclic loading were studied,including the surface morphology and failure process under loading with different proportions.According to the stress-strain curve,peak strain,residual strain and elastic modulus,the influence of rubber particle replacement rate on the mechanical properties of RC specimens was analyzed.The energy dissipation method was used to analyze the damage of concrete materials in the process of cyclic loading.The test results show that with the increase of particle size,the peak strain and residual strain of RC increase,and the elastic modulus decreases,so the rubber particles with small particle size have better mechanical properties.The damage variable calculated by energy dissipation method can accurately predict the damage process and the damage characteristics in the cyclic process;the larger damage occurs after the first cycle of RC,and the damage variable of concrete increases slowly with the increase of the number of cycles.It shows that the damage of RC under constant amplitude cyclic loading is almost the same in each cycle.Because the ordinary concrete(OC)has better mechanical properties than the rubber concrete in the early stage of the cycle,and there is no large damage variable in the first cycle.In order to compare the comprehensive performance of OC and RC,this paper uses the efficacy coefficient method to evaluate the comprehensive performance of OC and RC,and the result is RC-1>OC>RC-2>RC-3,so the most commonly mixed particle size is 0.85mm.The damage process of concrete under cyclic loading is the process of the original crack propagation,the generation and growth of new cracks.Some studies have shown that the propagation of concrete cracks to damage follows Weibull distribution.Therefore,based on this,the damage constitutive model of rubber concrete under cyclic loading was analyzed,and the proposed damage constitutive equation was verified by the test results.Through the fitting of the constitutive model parameters with the experimental data,the variation law of the fitting parameters was obtained.The correctness of the damage constitutive equation was further verified by combining the theory with the test.The optimal particle size of rubber particles was 0.85mm.Finally,the damage of rubber concrete caused by cyclic loading is visualized by means of scanning electron microscope(SEM).From the microscopic point of view,the optimal particle size of rubber particles was 0.85mm,which was consistent with the conclusion of damage constitutive model,which provides reference value for the application of rubber concrete in actual road engineering.Figure38 table19...