Hydrogen-bond-mediated damping enhancement in polymer-modified calcium silicate hydrate

Enhancing the damping capacity of cement-based materials is crucial for mitigating vibration and improving the long-term durability of structures subjected to dynamic loading. In this study, molecular dynamics (MD) simulations were performed to systematically investigate the effects of polyethylene (PE), polyvinyl alcohol (PVA), and polybutadiene (PB) on the mechanical properties and the damping performance of calcium silicate hydrate (C-S-H), the primary binding phase in cement-based materials. Results showed that polymers had little effect on the tensile strength of C-S-H but provided residual strength along the Z direction. Their influence on shear strength was negligible in the XY direction but considerable in the XZ direction. In addition, the hysteretic equivalent viscous damping, storage modulus, loss modulus, and loss factor were calculated from the hysteretic stress–strain curves. A considerable enhancement in the damping performance of C-S-H along the XZ direction was observed, while only limited improvement was found in the XY direction. Among three polymers, PVA exhibited the most pronounced enhancement of the damping performance of C-S-H along the XZ direction, with an approximately 13.68% increase in the loss factor. This improvement was attributed to the abundant hydroxyl groups in PVA, which can form H-bonds with C-S-H.