Numerical study of the influence of drying on properties governing the carbonation mechanism of concretes with low clinker content

This paper presents a numerical study of the coupling between cement hydration and drying of concretes with high amount of fly ash or blast-furnace slag and concretes with Portland cement or blended cements. The study, conducted with the MLS by FEMMASSE® code, aims at assessing the influence of drying on concrete properties governing carbonation kinetics, i.e. porosity, Portlandite content and liquid water saturation degree. These properties were found not uniform according to the depth within the concrete material. In the cover zone, high substitution concrete should have a higher carbonation risk than Portland cement concrete because of the slow hydration kinetics combined with the suspending effects of drying on hydration. Therefore, high substitution concrete should require a longer period of curing than Portland cement-based concretes.