Study of carbonation kinetics of a recycled sand

Abstract

Recycled sand from inert construction waste appears as a possible substitute for concrete production, not least because of the increased demand for sustainable building materials. This work explores the carbonation kinetics of a recycled sand. For this purpose, recycled sands (0/4) were exposed to CO₂ in a controlled carbonation chamber with two main points of interest: (i) a comprehensive study of the carbonation process; (ii) a monitoring of the mass and pH evolution during carbonation and the carbonation products from thermogravimetric analysis (TGA). Firstly, we have noticed a quick mass increase of the sand within the first eight hours of exposure to CO₂, indicating a rapid carbonation of the cementitious matrix; secondly, there are extended pH changes and significant CaCO₃ generation, indicating an extensive and intensive initial carbonation phase. The results were used to deduce the carbonation kinetic of the recycled sand used, which is useful for recycled sands processing strategies prior to their incorporation into concrete.