According to the characteristics of complex meso-structure composition and high heterogeneity of recycled concrete,a five-phase random convex polygon aggregate model including new and old mortar,new and old interfacial transition zone and natural aggregate was established by using Monte-Carlo principle,and the uniaxial compression simulation was carried out by combining with the plastic damage model of concrete.On the basis of verifying the rationality of the model,the failure mechanism of recycled concrete under uniaxial compression is studied,and the relationship between the failure of recycled concrete and the stress distribution is analyzed.The effects of the interface transition zone and mortar properties on the compressive strength of recycled concrete are discussed by adjusting the relevant parameters.The results show that the large-size aggregate and its shape play a key role in the failure of RAC.The concentration of tensile stress and shear stress is the main reason for the failure of RAC.The cumulative damage on the meso-level forms the macro-damage of RAC.The analysis shows that the priority of improving the compressive strength of RAC is new mortar,old mortar,new interfacial transition zone and old interfacial transition zone.
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