Luminous and bonding performance of self-luminescent cementitious coatings based on white cement and geopolymer

Self-luminescent cementitious coating (SLCC) shows great application prospects in newly constructed and existing traffic infrastructure to improve the effective brightness on the pavement. This work investigated the luminance of SLCC binders based on white Portland cement and metakaolin-based geopolymer. The bonding performance with the ordinary Portland cement substrate was also evaluated via the slant shear test. The results showed that a thin layer of hydrolysis reaction product was formed around the phosphor particle embedded in the geopolymer. The relatively higher pore solution alkalinity in geopolymer increased the degree of hydrolysis reaction of phosphor powders, leading to lower luminous properties than the white Portland cement binder. On the other hand, higher bonding performance with the substrate was also observed in the geopolymer binder. A gradual transition of Ca(OH)2 from cement substrate to geopolymer binder promoted the formation of C-ASH type gel in the interfacial transition zone to improve the bonding strength. After three months of weathering exposure, these two SLCC layers were able to tightly adhere to the concrete specimen and exhibit considerable luminescence, demonstrating the good overall performance during the field applications.