Pulse-Echo Ultrasonic Evaluation of the Integrity of Seams of Single-Ply RoofingMembranes: Results of Field Investigations and Recommendations

摘要

The report describes the second and final phase of a study to develop anultrasonic NDE method for evaluating the integrity of seams of single-ply roofing membranes. The results of the laboratory evaluation of a prototype pulse-echo apparatus (the field scanner) were positive in that voids could be distinguished from well-bonded sections of the specimen using the intensity of the echo from the adhesive layer. In the Phase 2 study, seams of existing EPDM single-ply membranes were examined by roof-top scanning to evaluate the performance of the field scanner in practice. This was followed by laboratory tests to confirm and explain observations made during the field tests of the seams. The field scanner was sensitive to micro-cavities, which could be generated in adhesive layers. This resulted in a number of 'false positive' readings. The formation of the micro-cavities was attributed to the temperature-induced volatilization of residual solvent remaining in the adhesive layer after its application on the membrane material.