Non Invasive Measurements of Moisture in Full-Scale and Brick Masonry Models After Simulated Flooding: Effectiveness of GPR

Within the framework of a European Commission project entitled Cultural HEritage against Flood (CHEF), a research was carried out in Milan on full-scale stone and brick masonry models by means of a simulated flood to investigate the effects of floods on historic and masonry buildings. The objective was to evaluate the post-flood moisture content and the drying process through non-destructive or minor-destructive techniques. Several non-destructive testing (NDT) were applied (thermography, sonic tests, radar) and were compared with the powder drilling test. Thermography and radar tests were the most useful; the attention is here more concentrated on radar tests which revealed interesting results. A high frequency GPR system was used to perform measurements on selected points of the models at selected intervals during the drying period. Radar velocity, radar amplitude in transmission and in reflection mode, radar waveform distortion and spectra were analyzed as a function of time after flooding and were compared to moisture content assessed by the powder drilling method. Measurements of radar velocity and radar waveform distortion were found meaningful and in agreement with the expected drying process.