Analysis Of The Fracture Process Of Concrete With High Volme Fraction Of Rubber Based On Meso-mechanics

Rubber concrete has good application prospects in water conservancy projects both for its superior impact and wear resistance,and recycling role of waste rubber products.However,with the high volme fraction of rubber added,the macro-mechanical properties of concrete such as compressive strength decrease obviously and the fracture mechanism is more complex than that of ordinary concrete.Based on the meso-mechanics method,a fracture numerical model of rubber concrete based on the true microstructure is established to simulate the evolution of the fracture process zone and analyze its fracture mechanism.The main contents and conclusions are as follows:(1)The micro structure of interface and the initial damage of high volme fraction rubber concrete were studied by means of micro-test methods and image processing technology.The results show that: The cracks at the interface between rubber and mortar are significantly larger than those at the interface between coarse aggregate and mortar,and the interface between rubber particles and mortar matrix is almost completely separated.There is no obvious difference in the length of microcracks at the interface between rubber and mortar with different rubber volme fraction.With the increase of rubber volme fraction,the number of microcracks at the interface between coarse aggregate and mortar decreases,but the difference of the average length of microcracks is small.With the increase of rubber volme fraction,the pore content of rubber concrete increases.(2)The meso-scale numerical model of rubber concrete was established.Based on the microstructure test results,the rubber concrete was regarded as a multi-phase composite material composed of mortar matrix,coarse aggregate,rubber particles,interface and initial defects.A meso-scale numerical model of rubber concrete considering the real structure was established to simulate the cube compressive and splitting tensile tests of concrete with different rubber volme fraction.The results show that: The model can simulate the failure process of rubber concrete and predictits strength.With the increase of rubber volme fraction,the compressive strength and splitting tensile strength decrease,and the decrease of compressive strength is greater than that of tensile strength.(3)Based on multiple research scales,a numerical model of rubber concrete fracture was established.For large-scale specimens,the micro damage and meso components were considered in the fracture process area,and the macro homogeneity was considered in other areas.The model of rubber concrete fracture across macro and meso was established.The effect of rubber volme fraction on fracture parameters was simulated.The results show that: With the increase of rubber volme fraction,the fracture toughness tends to increase first and then decrease.The size effect law of fracture performance was analyzed,and the size-independent tensile strength and fracture toughness of rubber concrete were given.