Valorization of Crushed Fly Ash Brick Waste as a Low‐Carbon Binder for Sustainable Concrete Production

The construction industry significantly contributes to global CO 2 emissions, with cement production being a major factor. Concurrently, large quantities of crushed fly ash brick (CFAB) waste accumulate due to manufacturing defects. In this study, CFAB powder was developed as a supplementary cementitious material (SCM) by partially replacing cement in concrete mixes at 5%, 10%, and 15% by weight. Mechanical testing revealed that 5% CFAB replacement improved 28‐day compressive and flexural strengths by 21% and 33%, respectively, which was attributed to enhanced pozzolanic activity and the formation of calcium silicate hydrate (C–S–H) phases, as confirmed by scanning electron microscopy (SEM), energy‐dispersive X‐ray spectroscopy (EDAX), X‐ray diffraction (XRD), and Fourier transform infrared spectroscopy (FTIR) analyses. Higher replacement levels reduced strength due to dilution effects. These findings demonstrate that CFAB can serve as a reactive low‐carbon binder, promoting sustainable concrete production and waste valorization aligned with circular economy goals.