Performance of silane -based surface treatments for protecting degraded historic concrete

Abstract Surface treatment is an effective way to protect existing historic concrete architectures from decay. Silane-based products could be considered as efficient protective materials to improve the concrete durability. However, preservation damages like appearance alteration and expansion stress of surface coatings have been reported. In addition, the long-term effect of silane coating has not been fully studied. In order to evaluate the efficiency of surface treatments and select appropriate materials for protecting historic concrete, three commercial silane-based products were applied on concrete specimens. The properties of the surface treatments on concrete in terms of appearance alterations, contact angles, compressive strengths, penetration depths and pore size distributions were investigated. An accelerated aging test was carried out in order to obtain a comprehensive understanding of the long-term preservation performance of commercial coatings. The results suggested that the three commercial products all showed protective features with little appearance change. However, some materials may lead to the white salt crystallization on the concrete surface, and strong hydrophobicity can easily generate tension and finally accelerate the concrete decay.