Effects of heat-treatment on physical and mechanical properties of limestone

Abstract

The susceptibility of buildings to fire makes it crucial to examine the physical and mechanical (P&M) properties of building stones under high temperature, which is necessary to predict and evaluate the safety and stability of stone structures. In this study, uniaxial compression (UC) and Brazilian splitting (BS) tests were performed on heat-treated limestone specimens and digital image correction (DIC) techniques were utilized to measure specimen deformation. Correlation analysis (CA) and principal component analysis (PCA) were conducted on the mechanical parameters obtained from the UC and BS tests, resulting in the establishment of three principal components (y1c, y2c and y1t) that comprehensively reflect the compressive and tensile properties; these were then utilized to analyze the sensitivity of mechanical properties to temperature changes. Furthermore, based on prior experimental data regarding the fundamental physical parameters of granite, one principal component (y1w) that comprehensively reflects fundamental physical characteristics was established and utilized to predict the uniaxial compression strength (σc) and tensile strength (σt). The results indicate that the compressive properties (σc, Poisson's ratio, elastic modulus and principal compressive strain) and tensile properties (σt and tensile strain) are all affected by temperature changes; as tensile strength is sensitive to temperature changes, special attention should be paid to fire and high temperature of stone buildings with the components subjected to the tensile stress; basic mechanical properties (σc and σt) can be well predicted by a principal component (y1w) which provides a new idea for calculating indirectly the residual mechanical properties of building stones after high temperature or fire.