Effects of Zn substitution on the mechanical and thermal transport properties of calcium silicate hydrate: a molecular dynamics study.

CONTEXT: Calcium silicate hydrate (C-S-H) was selected as the model system in this study. Pristine C-S-H and Zn-substituted C-S-H models, in which Zn replaced Si at either Q1 or Q2 sites, were constructed to investigate structural stability, tensile behavior, and thermal conductivity. The results show that Zn doping reduces the stability of the system. Q1 doping formed a more stable local coordination region, whereas Q2 disrupted silicate-chain continuity. Zn doping weakens the mechanical properties of C-S-H, with more pronounced reductions in the Y and Z directions. Zn doping lowers thermal conductivity in all directions, with Q1 affecting Z-direction interlayer transfer and Q2 affecting Y-direction chain transfer. METHOD: Molecular dynamics simulations (MD) were performed to study Zn-doped C-S-H. After energy minimization and NPT/NVT equilibration, structural characteristics were analyzed. Uniaxial tensile and non-equilibrium heat transfer simulations were then conducted to evaluate mechanical properties and thermal conductivity.