Influence of aggregate size and volume fraction on shrinkage induced micro-cracking of concrete and mortar

TL;DR

This study investigates how aggregate size and volume fraction influence shrinkage micro-cracking and permeability in concrete and mortar using nonlinear finite element analysis, revealing that larger aggregates and lower volume fractions increase crack width and permeability.

Contribution

It introduces a 2D lattice model to analyze the effects of aggregate size and volume fraction on micro-cracking and permeability, providing new insights into concrete durability.

Findings

Larger aggregate size increases crack width and permeability.

Lower volume fraction increases crack width and permeability.

Micro-cracking behavior depends on aggregate size and volume fraction.

Abstract

In this paper, the influence of aggregate size and volume fraction on shrinkage induced micro-cracking and permeability of concrete and mortar was investigated. Nonlinear finite element analyses of model concrete and mortar specimens with regular and random aggregate arrangements were performed. The aggregate diameter was varied between 2 and 16 mm. Furthermore, a range of volume fractions between 0.1 and 0.5 was studied. The nonlinear analyses were based on a 2D lattice approach in which aggregates were simplified as monosized cylindrical inclusions. The analysis results were interpreted by means of crack length, crack width and change of permeability. The results show that increasing aggregate diameter (at equal volume fraction) and decreasing volume fraction (at equal aggregate diameter), increases crack width and consequently greatly increases permeability.