Preparation and Performance of Nano-Silica-Modified Epoxy Resin Composite Coating for Concrete Subjected to Cryogenic Freeze–Thaw Cycles

Concrete is prone to deterioration and increased permeability under cryogenic freeze–thaw cycles. In this study, a novel method was proposed to prepare a nano-silica-modified epoxy resin composite coating with excellent anti-permeability. The effects of layer composition, a resin layer modified with different nanoparticles, and different nano-silica dosages on the oil impermeability of coated concrete were studied. The mechanical properties and chemical stability of the composite coating were also evaluated. The results showed that the composite coating composed of a nano-silica-modified resin layer, bonding layer, and surface layer presented good resistance to oil penetration under cryogenic freezing cycles. Moreover, nano-silica seemed to be a better choice for resin modification than nano-TiO2 and graphene. Macroscopic and morphological observation also confirmed a reduction in cracks and the integrity of the composite coating for concrete protection. Therefore, the coated concrete presented good mechanical properties and chemical stability. This study provides a guide for the preparation of composite coating concrete used for mountainous highway bridges and liquefied natural gas tanks.