Discussion On Interaction And Breaking Mechanism Of Recycled Aggregate Under Impact Load

With the development of China's social economy and the deepening of urbanization,a large amount of construction waste has been generated.According to statistics of relevant departments,China produces more than 3.5 billion tons of construction waste every year.Openair stacking or landfilling is currently the main method of processing construction waste.Simple disposal methods will not only cause environmental pollution,dust,land occupation,but also cause great waste of resources.According to the current building structure in China,bricks Mixed structures account for the highest proportion,so waste concrete and waste clay bricks are the two types of solid waste that account for the most construction waste.How to make full use of waste concrete and waste clay bricks in construction waste is an urgent problem to be solved.Studies have shown that recycled mixed aggregates made from construction waste can be used as roadbed or pavement base materials,and can also be used as gravel pile fillers.Recycled mixed materials are used as the above materials when compacted by vibration or impact In the process,it is necessary to study the crushing and interaction of mixed aggregates,but there is little public information on the impact crushing characteristics of mixed aggregates of recycled concrete and recycled clay bricks in existing studies.The physical and physical properties of recycled concrete and recycled clay brick aggregates The mechanical properties are very different.The interaction between waste concrete and clay bricks during the impact crushing of mixed aggregates is currently difficult to determine.In this paper,the construction waste generated after the demolition of an old building in a college in Taiyuan,Shanxi Province is taken as the research object.The treated 19mm-26.5mm recycled concrete and recycled clay bricks are mixed according to different qualities and then subjected to impact crushing test.The impact energy change and mixing ratio on the crushing characteristics of recycled aggregates were studied.The fractal dimension and relative crushing rate were introduced to characterize the crushing characteristics.(1)The law of fractal dimension change of recycled mixed aggregates under impact load is discussed.The amount of clay brick is positively correlated with the fractal dimension.(2)After the impact crushing of the aggregate,the peak appears at the particle size of 4.75mm-9.5mm.(3)The relationship between the relative breakage rate and the fractal dimension is discussed.The fractal dimension is positively correlated with the relative crushing rate,and the rationality of the fractal dimension as the quantitative index of impact crushing is discussed.(4)The impact of impact energy level on relative crushing rate,volume strain,fractal dimension,etc.After the accumulated energy reaches 9.92 kJ,the growth of relative breakage rate,body strain,and fractal dimension becomes slow.