INVESTIGATION OF MARBLE DETERIORATION AND DEVELOPMENT OF A CLASSIFICATION SYSTEM FOR CONDITION ASSESSMENT USING NON-DESTRUCTIVE ULTRASONIC TECHNIQUE

Abstract

The current paper investigates the influence of artificial thermal weathering on marble for the purpose of developing an improved classification system to assess marble deterioration based on non-destructive ultra-sonic velocity measurements. Different samples of historical Greek and Turkish marble used in Roman ar-chaeological structures in two Jordanian archaeological sites were selected and subjected to four heating cy-cles at different temperatures. The induced changes in the microstructure and physico-mechanical properties of the marble were examined and correlated with ultrasonic wave velocity measurements. Results showed that thermal weathering, particularly at temperatures beyond 200 ˚C, produces considerable microcracking in marble. The developed cracks act to significantly increase the porosity of marble and result in a corre-sponding significant reduction in ultrasonic velocity of marble. Consequently, a simplified relationship be-tween ultrasonic velocity and marble porosity has been proposed and an improved classification system for assessing marble deterioration has correspondingly been developed. This system allows for efficient assess-ment of the condition of archaeological marble objects and structures in a simple and non-destructive way. The results of this paper indicate that the deterioration of marble, regardless of its fabric characteristics, can reliably be assessed based on non-destructive ultrasonic velocity measurements. The consideration of rock fabric parameters, however, helps provide a more comprehensive evaluation and interpretation marble damage.