Strength characterization and sustainability assessment of coal bottom ash concrete

Coal bottom ash (CBA) which is waste and environment contaminant has been used in grinded and raw form as replacement of Portland cement (PC) and natural fine aggregates (NFA) in concrete. The combined effect of grinding period (GP) (2-10 h), grinded CBA (GCBA) (10-30%), and raw CBA (0-50%) on strength and microstructural characteristics was investigated and optimized along with its sustainability assessment. An enhancement in strength parameters with an increase in GP and replacement of PC and NFA with GCBA and CBA respectively was observed. The microstructural techniques like XRD, SEM, EDS, and FTIR also correlate with the aforementioned behavior. Mathematical models for strength parameters are well fitted and in good agreement with experimental and predicted values. Multi-objective optimization suggested 6.38 h grinding, 24.21% GCBA, and 32.96% CBA as the optimum values. CBA-based optimized mix resulted in 19.79% and 22.6% lower carbon footprints and eco-cost than the control mix.