Study On Dynamic Tensile Properties Of Recycled Aggregate Hydraulic Asphalt Concrete At Different Temperatures

With the rapid development of urbanization,the production of a large number of construction waste brings serious problems to the society,economy and ecological environment.At present,crushing and processing waste concrete into recycled aggregate and road base filling is an effective means to solve the problem of waste concrete,although a large amount of construction waste can be consumed.However,the potential engineering and economic benefits of recycled aggregate with relatively good quality are also covered up.Therefore.in order to greatly improve the utilization efficiency and engineering benefit of recycled aggregate in engineering,this paper applies recycled aggregate to hydraulic asphalt concrete and forms recycled aggregate hydraulic asphalt concrete instead of natural aggregate.Combined with the working environment of hydraulic asphalt concrete,in view of its possible structural tension and crack failure and other safety problems,the tensile performance of recycled aaggregate hydraulic asphalt concrete is studied in order to ensure its sufficient strength and impervious performance.the purpose of this paper is to provide a basis for popularizing recycled aggregate to hydraulic asphalt concrete.Based on this,the main research contents of this paper are as follows:（1）The specimens are prepared with the mixture ratio determined by our group throegh single factor test（the replacement rate of recycled aggregate is 50%）,and the direct tensile tests of recycled aggregate hydraulic asphalt concrete specimens are carried out under the conditioners of temperature range of-10～10℃ and strain rate of 10-5～10^-2 s^-1.The effects of temperature and strain rate on mechanical parameters such as tensile strength,elastic modulus,peak strain and failure mode of recycled aggregate hydraulic asphalt concrete are studied.The test results shew that with the decrease of temperature or the increase of strain rate,the tensile strength and tensile modulus of recycled aggregate hydraulic asphalt concrete specimens increase,the peak strain decreases,and the proportion of aggregate fracture in the fracture surface of the specimen increases.Based on the test results,the logarithmic dynamic enhancement factor is used to quantitatively describe the effect of strain rate on the tensile mechanical parameters.The results show that the dynamic enhancement factors of tensile strength and tensile modulus of recycled aggregate hydraulic asphalt concrete increase linearly with the increase of strain rate.And the slope of the fitting curve shows that the higher the temperature,the greater the dynamic enhancement factor.（2）In this paper,the tensile properties of natural aggregate hydraulic asphalt concrete are compared with those of natural aggregate hydraulic asphalt concrete under the same working conditions,and the similarities and differences between them are analyzed.The results show that in the range of temperature 0～10℃ and strain rate 10-5～10^-2 s^-1,the tensile strength and tensile modulus of recycled aggregate hydraulic asphalt concrete are lower than those of natural aggregate asphalt concrete to a certain extent,in which the decreasing amplitude of tensile strength is（26%-49%）and that of tensile modulus is（15%-67%）.（3）According to the mix ratio parameters of recycled aggregate hydraulic asphalt concrete,the numerical model of flexible cluster particles based on cluster is established by PFC3D discrete element software,and the evolution law of meso-mechanical parameters of recycled aggregate hydraulic asphalt concrete model under specific working conditions is analyzed.The effects of different temperature and strain rate on the failure mode,crack evolution,particle displacement development,three-dimensional fabric anisotropy evolution and energy evolution of recycled aggregate hydraulic asphalt concrete model are obtained.The tensile failure mechanism of recycled aggregate hydraulic asphalt concrete was revealed from the mesoscopic point of view.The numerical analysis results are in good agreement with the experimental results and have a high level of accuracy.