Self-healing lime mortars: an asset for restoration of heritage buildings

Natural hydraulic lime-based mortars are recommended for retrofitting operations in historical buildings, primarily because of their high chemical, physical and mechanical compatibility with the existing mortars; moreover, their autogenous and engineered self-healing capacities make them a suitable material for the aforementioned interventions. The authors’ group has undertaken a comprehensive investigation on the topic, developing tailored methodologies for the assessment and characterization of the healing capacity of lime based mortars at the material and structure subassembly level, and have addressed a constitutive modelling approach which incorporates the effects of healing scenario on the response of lime based mortars. At the material level the methodology was based on pre-damaging specimens, at different ages and levels of damage (70% of the compression strength in pre-peak regime; 90% of the compression strength in post-peak regime), curing them under different exposure conditions for the healing to occur, and retesting them after scheduled “healing period” to evaluate the recovery of physical and mechanical properties. At the sub-assembly level the same concept was applied to brick-mortar specimens, to evaluated the effects of healing on the brick-mortar bond, meant a crucial to the structural behaviour of the masonry render. The paper summarizes the main results obtained with a focus on the scalability of the healing results from the material to the subassembly to the structural level, as required for engineering applications.