Mechanochemical transformation of waste bricks: A study on grinding optimization and pozzolanic activity

Optimizing the grinding conditions for waste brick powders can substantially enhance their pozzolanic reactivity, making them effective supplementary cementitious materials (SCMs). This study investigated various milling parameters, such as material filling ratio (MFR) and grinding duration, to assess their impact on the reactivity and performance of waste brick powders. The results identified an optimal MFR of 0.8 and a 60-min grinding duration, which produced a strength activity index (SAI) of 97 % and a compressive strength of 46.9 MPa after 28 days. Analytical techniques, including X-ray diffraction (XRD), Frattini tests, and thermogravimetric analysis (TGA), confirmed the enhanced pozzolanic activity of the optimized samples, evidenced by significant calcium hydroxide consumption and reduced particle size. Further, isothermal calorimetry and scanning electron microscopy (SEM) observations highlighted improvements in reactivity and microstructural integrity. The findings demonstrate that by carefully optimizing grinding parameters, waste bricks can be effectively transformed into high-performance SCMs, contributing to sustainable construction practices.