Damage Assessment by Ultrasonic Images in Concrete Subjected to Freeze-Thaw Cycles

This paper reports on damage evaluation of concrete subjected to freeze-thaw cycles using ultrasonic images. The use of automated ultrasonic inspection systems supplies velocity and attenuation maps, providing the spatial variations in velocity and attenuation in concrete specimens with high resolution. Assessment of damage in concrete specimens is conducted defining several parameters extracted from the ultrasonic images obtained before and after the freeze-thaw cycles. These parameters are related to surface scaling and internal cracking. Experimental trials were carried out using different concrete specimens with and without air-entraining agents. Comparisons between the parameters obtained from the ultrasonic images and the failure criterion defined by the standard ASTM C666/C666M-03 are performed. As a result, this work shows the feasibility of using ultrasonic images as an effective tool for evaluating freeze-thaw damage in concrete.