Fracture toughness of calcium-silicate-hydrate grains from molecular dynamics simulations

TL;DR

This study uses molecular dynamics simulations to determine the fracture toughness and related properties of calcium-silicate-hydrate grains, revealing their ductile fracture behavior at the atomic scale, which informs the design of tougher cement.

Contribution

First-ever calculation of fracture toughness and related properties of C-S-H grains at the atomic scale using molecular dynamics simulations.

Findings

C-S-H exhibits ductile fracture behavior at the nanoscale.

Values for fracture toughness, critical energy release rate, and surface energy are reported.

Understanding nanoscale fracture properties aids in designing tougher cement materials.

Abstract

Cement is the most widely used manufacturing material in the world and improving its toughness would allow for the design of slender infrastructure, requiring less material. To this end, we investigate by means of molecular dynamics simulations the fracture of calcium-silicate-hydrate (C-S-H), the binding phase of cement, responsible for its mechanical properties. For the first time, we report values of the fracture toughness, critical energy release rate, and surface energy of C-S-H grains. This allows us to discuss the brittleness of the material at the atomic scale. We show that, at this scale, C-S-H breaks in a ductile way, which prevents from using methods based on linear elastic fracture mechanics. Knowledge of the fracture properties of C-S-H at the nanoscale opens the way for an upscaling approach to the design of tougher cement.