Use of glass powder residue as an eco-efficient supplementary cementitious material

Supplementary cementitious materials (SCM) are proven to be an efficient alternative to lowering concrete carbon footprint by partially replacing cement on its mix design. Glass powder residue (GPR) has great potential to improve concrete's mechanical performance, and its durability by suppressing the alkali-silica reaction (ASR). However, those qualities can only be achieved by reducing the GPRs particles sizes below cement to fill the binder gaps. In this context, the main objective of this research was to evaluate the grinding parameters to obtain GPR, resulting from the polishing process in the flat glass industry, with the desired properties as SCM. Grinding time was monitored and correlated with glass particle size distribution (GPSD). Optimum GPSD was crossed with mechanical characteristics and ASR reduction in mortars. GPR was tested in 0%, 10%, 15%, 20% and 25% of partial replacement in Brazilian Portland-Pozzonlan cement in mortars and pastes. Consumption of calcium hydroxide was also observed. Four hours of grinding was shown to be the optimum grinding time to lower the GPSD below cement. Moreover, tests suggest that 20% of grinded GPR can be used as partial cement replacement in mortars without lowering its compressive strength and showed positive mitigation in alkali-silica reaction at 14 days of observation. According to the results for the parameters studied, although mortars with 15% of GPR partial replacement had the highest efficiency and performance index, 20% can be considered the maximum GPR replacement content. Any increase represents a decrease in efficiency and performance. The eco-efficiency is observed with the reduction of energy needed to produce cement, as the level of replacement by GPR increases. Therefore, grinded GPR can be an alternative in the production of more environmentally friendly cementitious materials.