Concrete powder waste as a substitution for Portland cement for environment-friendly cement production

The use of recycled concrete powder (RCP) as a supplementary cementitious material (SCM) to clinker may be an alternative for reducing emissions associated with Portland cement (PC) and the construction and demolition waste (CDW) disposal problem and is the aim of this study. The compressive strength at 28 and 91 days and CO2 emissions from Portland cement (PC) matrices with RCP replacement at 0%, 7%, 15%, and 25%, comminuted for 0, 0.5, 2, and 6 h were evaluated. The materials were characterized by X-ray diffraction (XRD), thermogravimetry (TG), X-ray fluorescence (XRF), laser granulometry, Blaine fineness, and specific mass. The results indicated the compressive strength of cement with 15% and 25% RCP as filler met the C40 and C32 class requirements of the Brazilian technical standard for cement, with the potential to mitigate CO2 emissions by up to 25%. The use of RCP in cement mortars indicated the potential for reducing binder consumption (kg.C.m  3. MPa  1) by 9% and carbon emissions (kg.CO2.m  3.MPa  1) by 8% at 91 days, showing to be a promising alternative for the production of environment-friendly cement.