Influence of supplementary cementitious materials on the performance and environmental impacts of reactive magnesia cement concrete

This paper investigated the performance and environmental impacts of reactive magnesia cement (RMC)-based formulations containing pulverized fuel ash (PFA) and ground granulated blast furnace slag (GGBS). Concrete samples, whose binder component was composed of RMC with 0–50% PFA and GGBS replacement were subjected to carbonation curing for up to 28 days. The performance of each sample was analyzed and compared to corresponding Portland cement (PC)-based samples via porosity, water sorptivity, compressive strength and thermal conductivity measurements. The performance results were supported with the assessment of the environmental impact of each sample throughout their production and utilization phases. Samples in which 50% of the binder component was replaced by PFA indicated the highest strength development, reaching strengths as high as 60 MPa at 28 days, which were 33% higher than those of the corresponding RMC control sample. The advantageous strength gain demonstrated by RMC-PFA samples was associated with a reduction in sample porosity due to the filler effect of PFA as well as the formation of strength providing phases through the hydration and carbonation reactions. The use of both PFA and GGBS decreased the environmental impacts of RMC formulations, which was reflected as lower CO₂ emissions, as well as reduced damage on human health and eco-system quality when compared to RMC and PC samples. The environmental efficiency calculations involving a combination of the net CO₂ emissions and mechanical performance of each sample revealed the benefits of supplementary cementitious materials within RMC formulations.