Characterisation and damage analysis of old mortars

The scope of Rilem Committee TC167-COM is the characterisation of old mortars, with respect to their repair. For damage analysis of historic buildings, the characterisation of the old mortars may represent an essential part of the investigations. This statement can also be inverted, keeping in mind the scope of the committee and more specifically the second part ‘with respect to their repair’. It is essential to have knowledge of the condition of the old mortar and of the causes of any decay that has occurred (VAN HEES et al., 2000). The aim of this article is to underline the importance of knowledge on the factors that influence the way in which degradation of materials- and especially mortars in monuments - occurs. The most common forms of degradation of mortar in monuments, as well as the type of investigation, which is necessary to understand the cause of the damage, are described. On the basis of the assessed decay form and decay process, the most adequate repair method and the most suitable repair mortar can be chosen. The diagnosis of the damage is very often forgotten in practice, even though this is a fundamental step to guarantee a compatible and durable restoration. Such negligence can lead to major incompatibility problems in the case of repair mortar application. The approach discussed in this document can result in a better understanding of the causes of incompatibility and in guidelines for compatible repair mortars, based on the specific conditions of the individual monument. This article describes the approach, as proposed by Rilem TC167-COM .