Ultrasonic equipment aimed to detect grouting homogeneity in geothermal heat exchangers

The purpose of this study is to assess homogeneity and integrity of cementing grout in vertical borehole heat exchangers used for geothermal heat pumps using an ultrasonic non-destructive test. The used testing equipment, TUC (Ultrasonic Test to certificate grouting Continuity), is based on an ultrasonic system able to generate and record wave propagation from the inside of heat exchangers to the surrounding (cementation and soil, possibly). Differences in signal characteristics of the recorded waves along the pipe can indirectly provide useful information to evaluate the successful realization of the well cementation in terms of vertical homogeneity and continuity. Both laboratory and field tests have been evaluated and are hereafter presented to verify tests effectiveness and discuss eventual limitation of the proposed approach.