Insights at the neutron irradiation-induced structural homogenization effect of calcium silicate hydrates and degradation mechanism of mechanical properties: a molecular dynamics study

Abstract

Concrete has been widely applied in nuclear facilities, however, knowledge about the degradation mechanisms of cementitious materials due to irradiation is still limited. Therefore, in this work, molecular dynamics was employed to investigate the influence of irradiation energy on the structure and mechanical performance of calcium silicate hydrates (C-S-H, primary hydration products of Portland cement). Simulation results indicate irradiation leads to an isotropic structure transformation of C-S-H. The strength and stiffness of C-S-H along the in-plane direction was substantially reduced by irradiation, regardless of compression or tension loading. It is caused by the shortening of mean chain length of silicate tetrahedra, as well as the increase in the number of cracks and pores. Furthermore, an increase in the ductility of C-S-H is also observed, which is related to reorganizations and re-polymerizations of silicate tetrahedra on high-stress conditions. The mechanisms interpreted here pave the way to designing more irradiation-resistant cement-based materials.

Keywords:

• calcium silicate hydrates
• irradiation
• mechanical performance
• molecular dynamics
• isotropic structure

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

We acknowledge support from the National Natural Science Foundation of China (Grant Nos. 52050128, 51908119, 6512009004A, and U1706222), the Natural Science Foundation of Jiangsu Province (Grant No: BK20190367) and the Fundamental Research Funds for the Central Universities (2242021R41124). We are also grateful to the High Performance Center (HPCC) of Nanjing University for doing the numerical calculations in this paper on its IBM Blade cluster system.