Luminous and Bonding Performance of Self-Luminescent Cementitious Coatings Based on White Cement and Geopolymer: A Comparative Study

Abstract

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 performed a comparative study on 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 the geopolymer binder had lower luminous properties than the white Portland cement binder. The relatively higher pore solution alkalinity in geopolymer enhanced the degree of hydrolysis reaction of phosphor powders. 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-A-S-H type gel in the interfacial transition zone to improve the bonding strength. These two SLCC layers were able to tightly adhere on the concrete specimen and exhibit considerable luminescence after 3 months of weathering exposure, indicating to the good overall performance during the field applications.

Keywords: Self-luminescent, Cementitious coating, geopolymer, Luminous performance, Bonding performance