The effects of site modification on the physical properties of stone restoration mortar

Commercially-produced ‘restoration mortars’ are increasingly being used in stone masonry conservation. The convenient ‘mix and go’ approach of these materials is opening up the area of masonry repair to a wider, lesser skilled, consumer base. Pragmatic site practice with restoration mortars often leads to the modification of materials with the aim of providing enhanced workability, fitting with varying weather conditions and project timescales. This work aims to establish the resilience of one such proprietary restoration mortar to variations in its preparation and finishing. The properties of the material, and therefore its performance in service, are significantly influenced by variations in mixing regime, surface finish and pigmentation. Results highlight the impact of workmanship on the material’s properties and the need for a thorough understanding of the product prior to specification, preparation and application.