Laboratory testing of non-standard original historic building materials and related implications for conservation

Abstract

For an assessment or an analysis of a historic building, determination of the material properties is always crucial. However, this is usually a challenging issue because material extraction from a historic building for standard laboratory testing is usually not allowed or the amount of material available for testing is very limited. Lack of comprehensive standards for testing irregularly shaped and non-standard-size specimens, taken from historic buildings, unfortunately compounds the uncertainty. This paper offers a discussion of such issues by using the case study of Odda’s Chapel in Gloucestershire, UK, and describing the systematic examination of a total of six lime mortar and Blue Lias stone samples extracted from this Grade I listed building. The programme of testing and the results obtained are compared with the latest European standards relating to sampling and testing of material of cultural properties. Internal microstructure, hygroscopic sorption and water absorption characteristics, and the density and mechanical properties of the materials are documented and alternative testing techniques are compared. Identification of some of the above-mentioned material properties shows that the agreement between results obtained from the various test methods is considered satisfactory, depending on the testing approach and material heterogeneity.