Unraveling concrete's interfacial transition zone vulnerability under erosive environments: A molecular dynamics study

Abstract

The Interfacial Transition Zone (ITZ) in concrete is considered to be the weakest region of the mechanical properties of concrete, owing to the prevalence of microcracks induced by various external factors. These microcracks facilitate the ingress of corrosive solution into the ITZ through pores or crevices, ultimately impacting its mechanical integrity. This study aims to investigate the effects of different erosive environments on the mechanical properties of concrete ITZ and to analyze the intrinsic weakening mechanism via molecular dynamics simulations. The effects of different water contents and different ionic solutions are individually discussed in this study. Simulation results demonstrate a distinct trend in the mechanical properties of ITZ, exhibiting an initial increase followed by a decrease with the rise of water content under various conditions. Moreover, the magnitude of the mechanical properties of ITZ exhibits a hierarchy under different ionic solution conditions, ranked as follows: dry >10 wt% Na2SO4+NaCl >5 wt% Na2SO4 > 5 wt% NaCl >5 wt% Na2SO4+NaCl > H2O. The mechanical properties of ITZ are significantly influenced by its internal chemical bonds, which are susceptible to erosion from the infiltrating solution, resulting in the rupture of original chemical bonds and consequent reduction in ITZ's mechanical strength.