Efficient utilization of waste CRT glass in low carbon super-sulfated cement mortar

Abstract

This study developed a novel low carbon super-sulfated cement (SSC) mortar prepared with multiple types of solid wastes, including phosphogypsum and cathode ray tube (CRT) panel glass. The properties of this cement mortar were compared with the OPC/river sand counterpart with respect to durability and environmental performance. The pozzolanic reaction between the active surface of the CRT glass and matrix in the SSC improved the interface performance. The SSC mortar also showed lower water sorptivity associated with the denser microstructures, the finer pore size, and the lower connectivity of pores when compared to the conventional counterpart. Moreover, the high bulk electrical resistance of SSC mortar inhibited ions transport and further improved the durability. Meanwhile, the high sulfate environment and superior uptake ability to alkali ions of the generated C-A-S-H can effectively mitigate the alkali silica reaction-induced expansion in SSC mortar, even when 100% CRT glass aggregates were incorporated. However, the higher volume of mesopores in SSC than in OPC caused a higher drying shrinkage. The SSC provided a more promising outlet for the recycled CRT glass compared to OPC cementitious system in terms of environmental impacts (leaching and carbon footprint). The joint use of low carbon SSC and CRT glass can not only reduce 80% CO2 emissions by realizing the valorization of multiple types of solid wastes but also achieve better durability over the OPC system.