Mechanical characterisation of stone masonry of Batticaloa fortress, Sri Lanka

Abstract

Historical fortresses, traditionally constructed with stone masonry, require careful preservation to uphold their cultural significance. Understanding the material and mechanical characteristics of the stone masonry assemblies used in these fortresses is crucial for their conservation. Hence, an inclusive approach was taken to analyse the mechanical attributes of stone masonry utilised in a specific historical fortress in Sri Lanka. This comprehensive method involved two main steps: (a) expert evaluation and (b) non-destructive testing (NDT) techniques. This study incorporated well-established expert evaluation methods tailored for historical masonry, such as the masonry quality index, the geometric index and mechanical characterisation based on the Italian code for construction specifications. Additionally, two NDT methods – rebound hammer and ultrasonic pulse velocity testing – were employed alongside expert evaluations to understand thoroughly the mechanical properties of the stone masonry assemblies. The investigation focused on stone walls in ten different areas of the fortress, all of which were constructed using irregular and pebble stone masonry. The results obtained through NDT methods were then cross-referenced with the expert evaluations. This integrated approach effectively outlined the properties of the stone masonry assemblies, including compressive strength, Young’s modulus and shear modulus, providing a comprehensive characterisation of the structures.