Mesoscale modeling and failure mechanism of concrete considering pore structures and actual aggregate shapes

Abstract

This contribution focuses on the modeling and failure mechanism of concrete which is constituted by aggregates, mortar matrix, interfacial transition zones (ITZs) and pore structures. Firstly, actual geometrical shapes of aggregates were obtained by laser scanning technique. Secondly, a random aggregate placement algorithm and a pore structure generation algorithm were proposed to generate 2D concrete models which could realistically reflect the highly heterogenous meso-structure of concrete. Then, zero-thickness cohesive elements with traction - separation laws were embedded in the finite elements to simulate the complex fracture process and nonlinear mechanical characteristics. Finally, uniaxial compression simulations were carried out, and the effect of porosity and aggregate volume content on carrying capacity, elastic modulus and fracture process of concrete were investigated and compared with similar experimental results. The parametric study for cohesive elements is also conducted. Results showed that porosity and aggregate content have a significant influence on the mechanical properties of concrete, the mesoscale model is capable of simulating the failure process and mechanical behavior of concrete. The effect of each cohesive element parameter is clearly identified.