Preparation of infiltrating calcium carbonate layer in gypsum substrate using novel calcium precursor: The implication for the protection of the surface weathered carbonate heritages from water erosion damage

Abstract

Surface gypsification is a common problem for calcium carbonate historic construction materials. In this paper, a calcium carbonate protective layer was prepared in gypsum substrate using alcohol solution of calcium hydroxy glycolate. The concentration and penetration depth of alcohol solution of calcium hydroxy glycolate are as high as 2.0 M and 18.0 mm, respectively, which guarantees the sufficient introduction of calcium precursor at single treatment. Additionally, after introducing into gypsum substrate, calcium hydroxy glycolate can be transformed into calcium carbonate layer in the open air only when water was introduced subsequently, indicating that the calcium hydroxy glycolate is completely controllable in application. The results of FT-IR, SEM-EDX, XRD, IC and conductivity demonstrate that the prepared stable calcite layer can prevent the gypsum substrate from water corrosion efficiently. This exploring study provides a new solution for the protection of surface gypsification carbonate materials in the ancient constructions and relics.