Evaluation of Natural Building Stones’ Characterizations Using Ultrasonic Testing Technique

Natural building stones are widely used in the construction field in the Middle East and Mediterranean areas. Stones are chosen for their durability, attractiveness, and low cost compared to other construction materials. Building stones come with different natural origins and vary in their mechanical and thermal characterizations. Compressive strength, water absorption, and thermal conductivity of the external walls are significant characteristics in evaluating the structure's durability and sustainability. External walls that are made of natural stones with high thermal conductivity lead to extensive use of energy and raise ongoing costs for cooling and heating. In addition, low compressive strength and high-water absorption adversely affect the long-term durability of natural building stones. This paper aims to establish in-situ evaluation models of compressive strength, thermal conductivity, and water absorption of natural building stones using the non-destructive Ultrasonic Pulse Velocity (UPV) testing technique. Laboratory experimental tests were conducted for ninety-nine specimens of eleven types of natural building stones with dimensions of 50 × 50 × 50 mm. Based on the obtained results, UPV values depend on the mechanical properties of building stones. Ultrasonic pulse velocities of the building stones are directly proportional to their compressive strength and thermal conductivity with a satisfactory correlated relationship. However, UPV values are inversely proportional to water absorption with a non-sufficient correlated relationship. The results emphasize that there are slight differences in the obtained values of compressive strength of natural building stones that are loaded parallel or perpendicular to the natural rift. The study found that Ultrasonic Pulse Velocity testing technique is an easy-to-use, economical, and non-destructive method for a preliminary prediction of the mechanical and physical properties of natural building stones. Compressive strength, water thermal conductivity, and water absorption estimation models are proposed for field evaluation of building stones based on the Ultrasonic Pulse velocities.