Deterioration of natural hydraulic lime mortars, II: Effects of chemically accelerated leaching on physical and mechanical properties of carbonated materials

Masonry using lime binders is very common in all regions of the world. Models for the future climate in northern regions predict conditions conducive for the materials used in mass masonry being saturated for longer periods and therefore at higher risk of binder leaching and consequent deterioration. Following work on uncarbonated lime mortars, ammonium nitrate leachant was used to accelerate the deterioration of carbonated mortars containing natural hydraulic lime binders. Leaching of binder significantly reduced the strength of the mortar and slightly increased its sorptivity. The resistance to deterioration increased in the order NHL2 < NHL3.5 < NHL5 binder, in line with the increasing hydraulicity of the binder. Carbonated mortars are more resistant to binder leaching than the corresponding uncarbonated materials.