The role of moisture in the carbonation of cementitious materials

Abstract

It is well known that water, either in the solid, liquid or gaseous state, plays a prominent role in the behaviour of porous materials like cementitious composites.Carbonation is not an exception.The modification of the macrostructure of different hydrated cement pastes (hcp) due to carbonation is presented and discussed from the point of view of the water content which is a function of the relative humidity.The transport properties of the carbonated hcp for CO 2 and O 2 diffusion were measured with different water content.Finally, the carbonation shrinkage was also measured as a function of the relative humidity.It was found that carbonated materials were much less sensitive to the relative humidity of the surrounding atmosphere than noncarbonated ones.All these results lead to the proposition of a model of a porous system with two levels of porosity.