“…So far, a number of various approaches devoted to solving different problems have been proposed. Ultrasonic waves are most commonly used for crack detection [ 1 , 2 , 3 , 4 , 5 , 6 , 7 ], monitoring the hardening process [ 8 , 9 , 10 , 11 ], as well as for the quality assessment of the adhesive connection between concrete cover and reinforcement [ 12 , 13 , 14 , 15 , 16 ]. The method of scanning the surface opening cracks in reinforced concrete structures using transient elastic waves was developed by Liu et al [ 1 ].…”