Elastic constants of nano-scale hydrated cement paste composites using reactive molecular dynamics simulations to homogenization of hardened cement paste mechanical properties

Abstract

Calcium-silicate-hydrates, portlandite and ettringite are the main hydrated cement paste phases. The study of these phases might lead to a better understanding of the mechanical properties of hardened cement paste. In this work, molecular dynamics simulations were used to simulate different composites of these main phases. The objective were to obtain their elastic constants and to use them as a reference to calculate the homogenization of simplified hardened cement paste using Mori-Tanaka scheme. The results of calcium-silicate-hydrate/calcium-silicate-hydrate, calcium-silicate-hydrate/portlandite and calcium-silicate-hydrate/ettringite composites with three different orientations and configurations were obtained via molecular dynamics simulations using a software called LAMMPS. The homogenization of simplified hardened Portland cement paste gave the value of Young’s modulus in the range from 10.1 GPa to 15.1 GPa. This method might be able to determine Young’s modulus of normal hardened cement paste by the calculations of elastic constants of different composites with other hydrated and unhydrated phases.