Sustainable ternary cement blends with high-volume ground granulated blast furnace slag-fly ash

Coal fly ash and granulated ground blast furnace slag (GGBS) are more widely used as supplementary cementitious materials in cement production. This study investigates the influence of high-volume ordinary Portland cement (OPC) replacement with fly ash and/or GGBS on the flow, compressive strength and environmental impacts of the resulting binary and ternary blends. Experimental results showed that the use of ternary blends enhanced the flow characteristics, specifically with the incorporation of 20% to 30% fly ash. Overall, partially replacing OPC in the ternary and binary blends reduced the early-age compressive strength, while an improvement to the later-age strength was observed. Nevertheless, beyond 28 days, the inclusion of 20% and 30% of fly ash in the ternary blends exhibited the highest compressive strength. The results from life cycle assessment (LCA) revealed that the OPC is the key contributor to the environmental impact where 50% and 70% OPC replacement reduced on average 44% and 61% of the total impacts, respectively, regardless of the blending system. As such, effectively the eco-mechanical performance of blends was improved. The 70% ternary blends gave superior eco-mechanical performance (lowest GWP/strength ratio) in the presence of 10% and 20% of fly ash. This study also showed that the artificial neural network model can be developed and adequately used to predict the properties of the OPC blends (i.e. eco-mechanical performance). [GRAPHICS] .

Automated summary

Coal fly ash and granulated ground blast furnace slag are widely used as supplementary cementitious materials. This study found that incorporating 20-30% fly ash in ternary blends can improve flow characteristics. While partially replacing cement may reduce early-age compressive strength, it can improve later-age strength, with ternary blends containing 20% and 30% fly ash exhibiting the highest compressive strength after 28 days.