Compressive strength CO2 emissions from cements produced with concrete waste

Abstract

use of the fine fraction of concrete residue (RCF) as supplementary cementitious material (MCS) to clinker can be an alternative to reduce emissions associated with Portland cement (CP) and the problem of the disposal of construction and demolition waste, being the object of this study. For this, the compressive strength and CO2 emissions of Portland Cement (CP) matrices with replacement in volume of concrete residue (RC) of 0%, 7%, 15% and 25% were evaluated, as a function of the residue processing time (0,0. 5, 2 and 6 h). The materials were characterized by x-ray diffraction (XRD), thermogravimetry (TG), x-ray fluorescence (FRX), laser granulometry, Blaine fineness and specific mass. The results indicate that the compressive strength of cement with 15% and 25% of RCF as a filer meets the requirements for class C40 and C32 of the Brazilian technical standard of CP, with the potential to mitigate emissions per cubic meter by up to 25%. The use of RCF in mortars standardized according to NBR 7215:2019 indicated the potential for reduction ofligant consumption (kg.C. m-³. MPa-1) and carbon emissions (kg.CO 2.m-³. MPa-1) at 91 days by up to 14% and 13%, respectively, indicating that the alternative may be promising in reducing cement emissions.