Multiscale study of enhancing the fracture properties of interfacial transition zone: Insights from molecular dynamics and finite element simulations

Abstract

Cementitious composites are widely used in architecture and construction field, but usually show quasi-brittle failure at macroscale under tensile or bending loads. In contrast, the calcium silicate hydrates (C-S-H) exhibits noticeable ductile response at nanoscale. In this article, we focus on the interfacial transition zone between cement paste and aggregate, which consists of the C-S-H/quartz and the calcium hydroxide (CH)/quartz interface structures. To comprehend how a nanoscale design might improve concrete’s macro mechanical qualities, molecular dynamics and finite element simulations are performed at the nanoscale and macroscale, respectively. The elastic properties, modulus, fracture toughness and critical energy release rate of C-S-H/CH/graphene oxide (GO)/quartz composites are calculated using the molecular dynamics method at nanoscale. These parameters then are used in macro-simulation and calculating mechanical properties of macro concrete structures. The incorporation of GO sheets into the interface results in a 38.40% to 58.06% increase in the fracture toughness of interfacial transition zone (ITZ) systems and an 80% and 9.81% improvement in the tensile strength and tensile modulus of the concrete model, respectively. This fundamental insight into nanoscale interfaces notably allows for more accurate predictions of macroscopic mechanical behavior, paving the way for innovative and enhanced cement-based materials in the future.