Study on coatings for mitigating calcite scale in tunnel drainage pipes

Calcite blockage in tunnel drainage pipes can cause potential structural safety risks. This study investigated the anti-scaling performance of three coating materials, namely epoxy, silicone, and polytetrafluoroethylene, through indoor tests and in-situ experiments, spanning from macroscopic to microscopic levels. In addition, molecular dynamics calculations were also conducted to assess interfacial interactions between the coating materials and calcite solution contributing to calcite scaling. The results revealed that, compared with PE, the three coating materials exhibited inhibitory effects on the surface-induced heterogeneous nucleation of calcite. This suggests that these materials have the potential to reduce calcite blockage in tunnel drainage pipes. The results from molecular dynamics simulations were compared with the indoor tests and in-situ experiments. It revealed that the binding energy between the coatings and the calcite solution had a significant correlation with the anti-scaling property of the material. The results indicate that polytetrafluoroethylene exhibits the most effective anti-scaling performance. These findings provide a novelty strategic approach to addressing the issues related to calcite blockage in tunnel drainage pipes.