RILEM TC 277-LHS report: lime-based mortars for restoration–a review on long-term durability aspects and experience from practice

For conservation interventions of historic masonry generally lime-based mortars such as pure air lime mortars, lime-pozzolan mortars, natural hydraulic lime mortars and ternary mortars (lime-pozzolan-cement) are used. The main reason is that their hygric and mechanical (strength and ductility) performance are easy to adapt to most existing historic masonry (compatibility requirements). Although the basic appropriateness of lime-based mortars for restoration is undisputed, there are also some limitations in the application of these mortars. In this report a review is given of the theoretical backgrounds and further of laboratory research developments in the field of lime-based binders and mortars over the past decades. Furthermore, practical experiences in positive and negative sense (damage cases) are elaborated. Drawbacks and points of attention are being dealt with, which are essential for a durable application of lime-based mortars for the conservation of historic masonry. In genera...