To evaluate the potential of fly ash (FA) and ground granulated blast furnace slag (GGBFS) as supplementary cementitious materials (SCMs) in terms of sustainability and functional performance, both concrete and mortar samples were prepared with GGBFS or FA at moderate to high replacement ratios (35%, 50%, and 65%) and were tested for compressive strength, ultrasonic pulse velocity (UPV), chloride–ion penetration and migration, carbonation, and sorptivity, and the results of these tests were then used with the relative sustainability assessment of building technologies (MARS‐SC). At 28 days, the 35% GGBFS/65% ordinary Portland cement (OPC) mix achieved the highest compressive strength (~15% above plain OPC) with balanced durability, increasing GGBFS to 50–65% traded early strength for lower chloride ingress (lowest rapid chloride penetration test RCPT/rapid chloride migration test RCMT at 65% GGBFS). Plain OPC showed the best carbonation resistance, while sorptivity was highest for the 65% FA mix and lowest for the 65% GGBFS mix. Heat‐map summaries showed environmental performance improving with higher SCM content (rising from 0.44 for OPC to 0.66 for the 65%‐GGBFS mix), functional performance peaking at the 35% GGBFS mix, and economic dimension increasing with replacement level. The aggregated sustainability score (NS) identified the 35% GGBFS mix as optimal (NS = 0.74), Portland composite cement (PCC) (Type II A‐M) as the second‐best option (NS = 0.60), and the 65% FA mix as the poorest‐performing (NS = 0.42). Overall, a moderate GGBFS replacement (35%) was the most sustainable option, providing well‐balanced strength, durability, and embodied environmental impacts with suitable trade‐offs.
Harun et al. (Thu,) studied this question.