Characteristics analysis of long afterglow phosphor with SiO2 coating and evaluation its influence on the properties of self-luminescent cement-based materials

The long afterglow phosphors (LP) and reflective powders (RP) can be used in the preparation of self-luminescent cement-based materials (SLCM). However, the hydrolysis instability of LP combined with limited amount of LP and RP in SLCM have a degradation effect on the luminescent performance. This study proposes a solution by modifying the surface of LP as well as increasing the maximum amount of LP and RP to tackle this problem. Based on the modified Andreasen and Andersen model, the mix proportion of SLCM was firstly designed by 51% RP volume and replacing the cement volume (5%, 10%, 15% and 20%) by LP. The water resistance and morphology of LP with and without surface modification were examined. Furthermore, the surface modification and replacement level of LP on the compressive strength, luminescent performance and hydration kinetics were monitored. The phase assemblage, pore structure and morphology were also evaluated using XRD, MIP and SEM-EDS. The characteristics of LP showed that the surface modification not only changed its geometric shape but also improved its hydrolysis stability. Incorporating LP with optimal replacement and SiO2 modification in SLCM promoted the hydration process. The excessive addition of LP with surface modification was still inevitably detrimental to the development of strength, but it was favourable to strengthen the luminescent performance. Microstructure analysis showed that due to the low hydrolysis degree and well hydration process, the optimal replacement and surface modification of LP was more beneficial in pore refinement and microstructure compactness. Overall, incorporation of optimal amount of modified LP and RP in SLCM displayed excellent luminescent performance without compromising the hydration process and strength evolution.