Micromechanics-Based Simulations of Compressive and Tensile Testing on Lime-Based Mortars

TL;DR

This paper develops a micromechanics model to simulate the mechanical behavior of lime-based mortars under compression and tension, accurately predicting their strengths and fracture energy for conservation purposes.

Contribution

It introduces a novel continuum micromechanics model incorporating shrinkage cracking and damageable phases, improving prediction accuracy for lime-based mortar behavior.

Findings

Model predictions align well with experimental data.

Inclusion of shrinkage cracking improves simulation accuracy.

Compliant crushed brick fragments outperform stiff sand particles in mortar performance.

Abstract

The purpose of this paper is to propose a continuum micromechanics model for the simulation of uniaxial compressive and tensile tests on lime-based mortars, in order to predict their stiffness, compressive and tensile strengths, and tensile fracture energy. In tension, we adopt an incremental strain-controlled form of the Mori-Tanaka scheme with a damageable matrix phase, while a simple $J_2$ yield criterion is employed in compression. To reproduce the behavior of lime-based mortars correctly, the scheme must take into account shrinkage cracking among aggregates. This phenomenon is introduced into the model via penny-shaped cracks, whose density is estimated on the basis of a particle size distribution combined with the results of finite element analyses of a single crack formation between two spherical inclusions. Our predictions show a good agreement with experimental data and explain the advantages of compliant crushed brick fragments, often encountered in ancient mortars, over stiff sand particles. The validated model provides a reliable tool for optimizing the composition of modern lime-based mortars with applications in conservation and restoration of architectural heritage.