Mesoscale models and uniaxial tensile numerical simulations of concrete considering material heterogeneity and spatial correlation

Abstract

Concrete is a typical heterogeneous material with initial defects. Its internal structure is very complex and has unique mechanical and physical properties. At the mesoscale, concrete is regarded as a heterogeneous composite material composed of multiphase. A new procedure named “mesh – placement – identification – assignment” (MPIA) was proposed to establish the mesoscale model and assign material properties to each phase. The innovation of this work is that the assigned material properties can and effectively characterize the heterogeneity (randomness), continuity, and correlation of each phase in concrete. Weibull’s statistical distribution function was used to describe the heterogeneity of material properties, and the spatial correlation coefficient was introduced to consider the correlation and continuity of materials in space. Considering the ITZs as a part of mortar, the concrete is regarded as a two-phase composite material composed of aggregate and mortar. The proposed model named Concrete Mesoscale Concretization Model (Double CM) can effectively characterize the transition and transformation of mechanical properties from the surface of aggregate to the mortar interior. The uniaxial tensile simulation results show that the tensile strength of concrete can be improved by increasing the homogeneous degree, increasing the aggregate content, and using crushed stone aggregate. The increase of the spatial correlation coefficient will result in the concentrated distribution of the weak parts in concrete and decrease the tensile strength of concrete.