Mesoscopic Analysis And Numerical Simulation Of Mechanical Properties For Recycled Concrete Composite Materials With Interface

Concrete is a kind of complicated multiphase heterogeneous material, and thehomogeneous properties are assumed in the traditional macroscopic mechanical model, andthe mechanical parameters for this model are determined by the experimentation to satisfy theneed of the project. However, it is difficult to describe crack initial, propagation andcoalescence in concrete materials, which is caused by the damage process from mesoscopic tomacroscopic level under external load. In this paper, the recycled concrete is regarded asthree-phase composite materials including coarse aggregate, cement mortar matrix andbonding interface, and the macroscopical mechanical properties of recycled concrete areinvestigated by a mesoscopc mechanical method.Modulus of elasticity is a basic mechanical parameter for concrete, which is closelyassociated with the mechanical properties of concrete structure or component. Combining thedrawing function of AUTOCAD to the software of ANSYS with a strong grid processing andcomputational function，the representative volume element for different diameter of aggregatewith random distribution in the soft and hard matrix is established. The effective elasticmodulus for the three-phase composite material with random aggregate、matrix and perfectinterface is calculated by using the homogenization theory. The effects of the shape, size, anddistribution characteristics of the aggregates on the macroscopic mechanical properties areanalyzed. The influence of elastic modulus of random aggregate and the matrix on themechanical properties of recycled composites is investigated.Compressive strength is one of the most important and essential mechanical parametersfor concrete. Concrete is a kind of complex composite material, and the internal stressdistribution is not uniform under uniaxial compress for different aggregates, and the largertensile stress is produced by the occurrence of the stress concentration in the material, whichis the main reason for concrete compress failure. By using the mesoscopic damage mechanicstheory，a micro-structure model is established for the recycled concrete with randomaggregates in this paper. A damage constitutive equation for recycled concrete material isestablished to consider the influence of material parameters, such as the tensile strength of theaggregates and the interface, the damage parameters for each phase, and the size of the element and so on. The finite element software ANSYS is performed to calculate the effectivemechanical properties for recycled concrete materials with mesoscopic damage under uniaxialloads, and the failure process is simulated by the cube specimens under uniaxial compression,and the results are compared well with the existed experiment results.