UTILIZATION OF SONIC TESTS TO EVALUATE DAMAGED AND REPAIRED MASONRIES

When dealing with conservation of existing buildings, the detection of damaged areas of the walls and the evaluation of the level of damage are needed before deciding on the type and extent of repair. After rehabilitation, the effectiveness of the repair also has to be determined. Research has been carried out by the authors on the application of pulse velocity tests to the evaluation of the integrity of historic masonry structures and of the efficacy of masonry strengthening by injection techniques. Sonic tests appear to be more suitable than ultrasonic tests to detect large voids, flaws, cracks and delaminated bed joints, to evaluate walls of great thickness and to obtain clear waveforms for further processing. There being direct empirical correlations between masonry strength and sonic pulse velocity, limited by a high degree of scatter in the data, a rough guide for masonry quality is proposed based on different levels of pulse velocity values. The measurement of local effectiveness of masonry repair by injection is also proposed by using as a parameter the product amplitude by frequency of the fundamental wave.