Synergistic effects of fly ash, ground granulated blast furnace slag, and graphene oxide in low-carbon concrete: modelling, optimization, and sustainability assessment

The most widely used building material in the world is conventional concrete having high carbon footprint and highly dependent on natural resources. To overcome these challenges the present study focuses on the designing and assessing the performance of low-carbon concrete mixes using fly ash (FA), ground granulated blast furnace slag (GGBS) and graphene oxide (GO), various tests were performed to investigate the mechanical properties, microstructural characteristics and sustainable assessment of the developed mixes. Response surface methodology (RSM) was used to design the mixes incorporating 20% FA, varying GGBS (5-15%) and GO (0.02-0.08%). Among the developed mixes, mix with 15% GGBS and 0.05% GO an improvement was observed with an increase of 25.55%, 19.37%, 15.95% and 10.76% for compressive strength, flexural strength, modulus of elasticity and poisson's ratio respectively compared to control mix although addition of GO reduced slump of concrete mixes. FESEM images supported the experimental findings with dense microstructure of mixes with GGBS and GO. Models developed through RSM possessed high R² values and analysis of variance (ANOVA) confirmed significance of the developed models and reliability of the prediction. Sustainability assessment was carried out to evaluate embodied carbon, eco strength index and carbon footprint reduction and it indicated a 28% reduction in embodied carbon for the mix containing 20% FA, 15% GGBFS and 0.02% GO compared with the control mix, highlighting the potential of these materials in producing low-carbon concrete.