Estudio numérico computacional discreto de los mecanismos de fisura de una matriz de hormigón en compresión uniaxial

Abstract

In this project a discrete computational numerical model is performed that reproduces with some level of approach the crack behavior of concrete. The concrete is represented as a matrix composed of poly dispersed particles that simulate the aggregate, bonded by an adhesion model that reproduces the cement-sand paste’s function. The contact model defines the interaction of the aggregates, and the Johnson-Kendall-Roberts adhesion model is applied to bond the particles. The simulations are based in fundamental concepts of Discrete Elements Method technology. The fundamental objective of this work is to study the dynamics of the aggregates at the meso scale level, in order to identify the loss of uniaxial capacity mechanisms. Identifying these mechanisms could lead to an improved understanding of the physics that govern the material in compression behavior. The study considered three types of granulometry for gravel particles, with the purpose of analyzing their influence on the mechanical response of the discrete concrete model. Computational numerical experiments of the procedure described in ASTM C39 / C39M-18 were performed through LIGGGHTS software. The post data processing was done in Paraview and Matlab. It is concluded that when the nominal size of the coarse aggregate particles is greater, a lower uniaxial capacity is reached. Further, the largest forces of contact are concentrated in the coarse aggregate particles, and the kinematics of the fine aggregate particles trigger the first micro cracks, that develop into large visible fissures.