- Author
- Watanabe, H. | Rossiter, W. J., Jr.
- Title
- Pulse-Echo Ultrasonic Evaluation of the Integrity of Seams of Single-Ply Roof Membranes.
- Coporate
- Takenaka Corp., Tokyo, Japan National Institute of Standards and Technology, Gaithersburg, MD
- Book or Conf
- U.S. National Roofing Contractors Association. Symposium on Roofing Technology, 3rd International. April 17-19, 1991, Montreal, Canada, 72-83 p., 1991
- Keywords
- roofs | membranes | evaluation | seams | adhesives | rubber | ultrasonics | nondestructive tests
- Identifiers
- adhesive-bonding; field inspection; nondestructive testing; pulse-echo method; voids
- Abstract
- This paper summarizes results of a study to develop an ultrasonic pulse-echo method for evaluating the integrity of seams of single-ply roofing membranes. A prototype pulse-echo apparatus (the field scanner), which was designed to scan across seams of roofs while maintaining acoustic coupling to the seam surface, was developed. Results of initial laboratory investigations showed that voids in seams could be distinguished from well-bonded sections using the intensity of the echo from the adhesive layer. This echo was relatively weak for well-bonded seams, and relatively strong for voids. Seams of existing EPDM single-ply membranes were examined by roof-top scanning to evaluate the performance of the field scanner in practive. The findings indicated that the field scanner was sensitive to detecting micro-cavities that could be created in the adhesive layer at the time of seam fabrication, thus resulting in "false positive" readings. The formation of the micro-cavities were attributed to the temperature-induced volatilization of residual solvent remaining in the adhesive layer after its application on the membrane material. It was concluded that, at least in its present form, the field scanner had limited applicability to resolving micro-cavities from voids and delaminations in solvent-adhesive seams. It may be applicable to seams formed using other techniques.