Enchantment of architectural luminescent-glass mortar (ALM) properties with encapsulation of white-color powder

Architectural luminescent-glass mortar (ALM) possesses the ability to trap light in daytime and convert into visible light at night, can be used as a decorative building material. However, previous studies demonstrated that a transparent adhesive material used to mix with luminescent powder (LP) for coating on the surface of glass aggregate could significantly degrade the mechanical properties and UV aging resistance of ALM. To address these issues, this study proposes to use white-color powders (including white cement, metakaolin, ground granulated blast-furnace slag, calcium carbonate, quartz and glass powder) to envelop the luminescent glass coated with adhesive, for the purpose of eliminating the direct negative impact of the adhesive used in the production of ALM. The compressive strength, glow light performance and UV aging resistance of ALM were investigated. Results revealed that the use of white powders to encapsulate the luminescent glass led to a 20% increment of 28-d compressive strength (similar to 60 MPa) of ALM and improved the UV aging resistance as well as reducing the luminance decay value of about 15%. Microstructural analysis demonstrated that the encapsulation of white powders thickened the interfacial transition zone (ITZ) between glass aggregate and cement matrix due to the dispersion and dilution of the adhesive. Additionally, the white powder significantly densified the edge of the ITZ near the cement matrix, which was known to be the main reason for the performance improvement of ALM. The whiteness of white powders also played a crucial role in the glow light performance of ALM. Calcium carbonate (CC)-modified ALM exhibited the highest initial luminance and longest afterglow time (more than 8 h) due to LP extruded closer to the glass. As a result, it was more easily excited and emitting light through the glass directly without being attenuated by the adhesive layer.