A numerical chemo-micromechanical damage model of sulfate attack in cementitious materials

Abstract

The sulfate attack (SA) of cementitious materials widely exists, which severely reduces the mechanical properties and durability of cementitious materials. However, few numerical SA damage models of cementitious materials have been comprehensively developed. The understanding and simulation of the chemo-mechanical behavior of cementitious materials are beneficial to better modeling, predictions and designs of underground structures. In this research, a numerical chemo-micromechanical damage model under the SA and loading is proposed to explore the cracking process of the cementitious materials based on the discrete element method (DEM). Some inherent characteristics of the chemical attack can be well considered in the proposed numerical model. The local damage effect can be simulated, as well as the sulfate corrosion degree and the material component. The performance of this proposed model is confirmed and validated by available experimental results. We examine the dependence of the strength and the elastic moduli of the cementitious material on: (a) the content of ettringite, (b) the distribution of ettringite, (c) the mechanical properties of the cementitious matrix, (d) the void ratio of the cementitious materials, (e) the confining pressure, and (f) the expansion coefficient of sulfate corrosion products. The softening and fluctuating phenomena are witnessed in the stress-strain curves. The failure mode of cementitious materials with the SA is different from that of specimens without the SA. The damage parameters of cementitious materials under the SA are examined in depth. The numerical results reveal that the proposed damage model is feasible and valuable in the modeling, predictions, applications and durability of chemo-mechanical sulfate attack problems in cementitious materials.