Study on the influence of dry ice phase change behavior on the micropore structure and hydration properties of mining grouting materials based on experiments and molecular simulations

In order to study the temperature-regulating and retarding effect of phase change materials on cement-based materials, we selected dry ice as the phase change material and prepared a phase change thermal storage grouting material (PCGM) using dry ice, cement, and fly ash. Our findings from temperature conduction, scanning electron microscopy (SEM), X-ray diffractometer (XRD), and thermogravimetric testing demonstrate that dry ice can effectively diffuse into the pore structure of cement-based materials. Furthermore, we explored the influence mechanism of dry ice content and ambient temperature on the hydration performance of grouting materials using molecular dynamics simulation. The results reveal that the diffusion coefficient of CO2 increases with the rise in ambient temperature, while it slightly decreases with the increase in dry ice content, albeit not significantly. Water molecules tend to be adsorbed on the surface of the calcium silicate hydrate matrix, forming a layered structure. This phenomenon leads to reduced mobility of water molecules near the surface of the calcium silicate hydrate matrix.