Experimental Study On Dynamic Mechanical Properties Of Rubber Recycled Concrete

With the acceleration of China’s urbanization process,infrastructure construction is developing at a high speed,generating a large amount of construction waste.China’s annual output of used tires is 233 million,equivalent to 3 million tons of rubber resources.Innovative solutions for the challenges of tire handling problems have been under development.One of the feasible solutions for using waste tire rubber is to mix it into cement-based materials and replace some natural aggregates to prepare rubber recycled aggregate concrete(RRAC).In addition to the static load,concrete structures also need to withstand dynamic loads such as earthquakes,wind,and explosions,which cause concrete to deform at a strain rate much higher than static loads.Therefore,the performance of the structure under dynamic loads is particularly important.This paper mainly studies the hysteretic energy consumption,elastic energy storage,damping ratio,elastic modulus,stress amplitude,and strain amplitude of rubber recycled concrete specimens under an uniaxial compression cyclic loading.At the same time,the first-order natural frequency and damping ratio of the RRAC specimen under flexural vibration were studied when RRAC was undamaged and damaged caused by uniaxial compression cyclic loadings of0.1f_c-0.5f_cand 0.6f_c-0.8f_c.The damage index was defined and the relationship between the damage index and the damping ratio was discussed.The main conclusions are as follows:(1)The results of RRAC mechanical properties test show that the addition of rubber decreases the static mechanical properties of RRAC.When the rubber particle size is 1-2 mm and the rubber content is 10-30%,the average cubic compressive strength,average splitting tensile strength,average axial compressive strength,and average static elastic modulus of RRAC are decreased by 17.3%,7.3%,14.2%and14.7%compared to the RAC group.And when the rubber content is 10%,the cubic compressive strength,splitting tensile strength,axial compressive strength,and static elastic modulus are only decreased by 4.2%,2.4%,1.7%and 2.3%,respectively,compared with the RAC group.When it is 20%,the cubic compressive strength,splitting tensile strength,axial compressive strength,and static elastic modulus are respectively reduced by 23.0%,7.3%,14.7%,and 18.6%.When the rubber content is20%,the mechanical properties decrease significantly.(2)RRAC uniaxial compression cyclic loading test results show that hysteretic energy consumption,elastic energy storage and damping ratio increase with increasing rubber content and particle size.The elastic modulus of RRAC decreases with increasing rubber content and particle size.RRAC’s hysteretic energy consumption,elastic energy storage and damping ratio increase exponentially with the increase of stress and strain amplitude,while the elastic modulus decreases with the increase of stress and strain amplitude.As the loading frequency decreases,the RRAC damping ratio,hysteretic energy consumption,and elastic energy storage tend to increase,while the elastic modulus shows a downward trend.(3)The bending free vibration test results show that in the non-destructive state,the RRAC bending vibration damping ratio increases with increasing rubber content and particle size,and the first-order frequency is opposite.The surface treatment of the rubber particles with silane coupling agent and the addition of an antifoam agent reduce the RRAC damping ratio and increase the natural frequency.The RRAC damping ratio increases and the first-order frequency decreases as the damage index increases.