Ultrasonic pulse and resonance method–evaluation of the degree of damage to the internal structure of repair mortars caused by exposure to high temperatures

Abstract

When the repair mortars for the repair of concrete structures are exposed to high temperatures, it results in irreversible changes in their internal structure. These changes can be evaluated both on the basis of the compressive strength and flexural strength, but their evaluation can also be made using dynamic non-destructive methods. The article presents the findings on the use of parameters from the measurement by ultrasonic pulse and resonance method. Changes in the internal structure of repair mortars were evaluated on the basis of the dynamic Young’s modulus of elasticity and relative dynamic modulus of elasticity. The said parameters very well characterize the changes in the internal structure of the repair mortars, and their values decrease with the increasing temperature. Changes in the internal structure of the repair mortars also reduce the compressive strength and flexural strength. The researchers confirmed the suitability of the ultrasonic pulse and resonance method for evaluating the degree of damage to the internal structure of repair mortars exposed to high temperatures.