Composition and compatibility requirements of mineral repair mortars for stone – A review

• The aggregates, binders and their ratios determine the mortar’s properties.
• Developing repair mortars should be with respect to the ranking of its properties.
• Surface repair mortars can be advantageous but are now empirically made or adapted.

When designing repair mortars, it is important to consider all its components such as the binder and the aggregates since they have a great influence on the mortar’s final properties. The binder, and the aggregates' angularity and chemical composition determine the properties of the mortar, properties critical for a good compatibility and durability of a restoration intervention. In this article, some mineral repair mortar design philosophies are approached, followed by the requirements set for a plastic repair mortar for stone. Up to which point is an intervention compatible? An answer was found when examining several articles that discuss the compatibility tolerance plane. This article aims to give the reader a hands-on approach in mineral repair mortar design and how this can be used to make a mineral repair mortar more compatible with the substrate.