RILEM TC 203-RHM: Repair mortars for historic masonry. The role of mortar in Masonry: an introduction to requirement for the design of repair mortars

Mortar has been in use for many thousands of years and is integral to most masonry construction. Is use is widespread in every culture where masonry is constructed. It is present in the majority of the global built cultural heritage, and is therefore a major consideration in building conservation. The effettive design of a motar for repairing masonry depends on a clear understanding of its function. The main functional uses of mortars in masonry are classified as bedding, ointing, grout, render, plaster, flooring and mortars for surface repair. The requirements that each type of mortar must meet in service depend on its environmental exposure and its role in the masonry element that it is found within (e.g. issue such as historic authenticity, aesthetics, resistance to moisture ingress, structural integrity, and service life). Technical requirement such as adhesion, strength, elasticity, water and vapour transmittance, drying behaviour, thermal dilatation, ability to deal with salt contamination and freeze-thaw cycling, and its aesthetic properties can be quantified. Mortars properties can be adjusted by varying ingrdients and their proportions, to meet the deffering technical requirements.