Comparative experimental study of the mechanical and fracture properties of Portland limestone and Corsehill sandstone

Aikaterini Marinelli,Matthew Stewart

doi:10.3221/igf-esis.50.37

Abstract

An experimental investigation of the mechanical and fracture characteristics of Portland limestone and Corsehill sandstone is undertaken, aiming at enhancing understanding of the structural behaviour of these natural building stones commonly used in both new and restoration projects in Edinburgh, Scotland. A series of three-point bending and four-point bending tests on appropriately cut prismatic samples, in the presence of U-shape notches, were performed and results were interpreted following the concepts of crack mouth opening displacement and fracture energy. The critical crack opening displacement could be further investigated as a fracture criterion, independently of the method used for its determination. At a second stage, the effect of specimen shape and size on flexural strength, deflection at mid-span, crack mouth opening displacement and fracture energy was studied for Portland limestone. Despite the scattering of results, trends observed comprise (a) the negative correlation between the flexural strength of Portland limestone and the specimen span length and (b) the positive correlation between fracture energy and specimen size. Conclusions drawn are in good agreement with similar ones for other quasi-brittle materials and contribute to the assessment of the fracture behaviour of full size structural members that are often beyond the range of possible failure testing.

Highlights

Historical buildings and monuments reflect the significance of cultural heritage and indicate the diversity of civilizations, showing the history of the past while revealing local identities
The development of suitable methodologies of experimental investigation for two natural building stones used widely in construction projects in Edinburgh was approached through an experimental study comprising both non-destructive and destructive testing
The further objective of this research was to examine the effect that test specimen size and shape have on several key properties of Portland limestone, including deflection at mid-span at peak load, CMOD at peak load, flexural strength and, in particular, fracture energy

Summary

Introduction

Historical buildings and monuments reflect the significance of cultural heritage and indicate the diversity of civilizations, showing the history of the past while revealing local identities. The built heritage has formed the foundation of many successful regeneration projects in many cities across the United Kingdom (UK). Local historic buildings add to the unique character of a region, help to promote a sense of community and have a significant part in creating a sense of place and differentiation. These places of cultural significance must be conserved for present and future generations in accordance with the principle of inter-generational equity [1].

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