Two-dimensional X-ray CT image based meso-scale fracture modelling of concrete

TLDR

The study builds two‑dimensional meso‑scale finite‑element models of concrete from high‑resolution X‑ray CT images, embeds cohesive elements at cement paste and aggregate–cement interfaces, and simulates tension tests on many specimens with statistical analysis. The simulations reveal that load‑carrying capacity and crack patterns vary strongly with the random distribution of phases, that tensile strength declines with increasing void fraction, and that the relative strengths of cement paste and interfaces govern micro‑cracking behavior, which in turn controls macro‑cracking and overall load capacity.

Abstract

Two-dimensional meso-scale finite element models with realistic aggregates, cement paste and voids of concrete are developed using microscale X-ray Computed Tomography images. Cohesive elements with traction–separation laws are pre-embedded within cement paste and aggregate–cement interfaces to simulate complex nonlinear fracture. Tension tests using a large number of images were simulated with statistical analysis. The very different load-carrying capacities and crack patterns demonstrate the effects of random distribution of phases. It is found that the tensile strength decreases as the void fraction increases, and the relative strength of cement paste and interfaces dominates the microcracking behaviour, which in turn affects macrocracking and load-carrying capacity.