Nanoscale insights into concrete fracture via reactive molecular dynamics simulations

A major threat to the structural integrity of concrete structures is the fracture brought on by wear and tear, especially for the structures subjected to repeated stresses such as pavements, bridges, and building components. To ensure the durability and serviceability of concrete structures, it is essential to understand the atomic-level mechanisms that control crack formation. Atomistic modeling is a powerful technique for exploring complex interatomic interactions and offers a way to thoroughly examine material behavior. This method makes it easier to comprehensively investigate the initiation and propagation of cracks as well as the resulting microstructural changes. The study aims to analyze the fundamental parts of concrete, concentrating on Calcium-Silicate-Hydrate (CSH) and mineral aggregates (silica). Using molecular dynamic simulations, a mortar-mineral aggregate composite model is developed and tested under tensile loading. The LAMMPS software is utilized to carry out these simulations, which provided insightful information about the underlying mechanisms governing the crack propagation. The model successfully captures the stress-strain behavior of CSH, silica and their interface. Silica has the highest tensile strength due to its layered structure followed by CSH and interface. The effect of varying strain rates on the fracture parameters reveals the dominance of crack bridging mechanisms at lower strain rates. Thus, the MD simulations have the potential for in-depth analysis of structural response and service life of structures.