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Abstract
This investigation was a limited study of seams in an EPDM rubber membrane of the roof of the new "Wheeled Vehicle Facility" building at Aberdeen Proving Ground, Maryland. The study was initiated at the request of the Corps of Engineers to provide data that could contribute to a database on the characterization of newly prepared field seams. The investigation was beneficial to NIST because it complemented laboratory research on test methods for evaluating seams of vulcanized rubber roof membranes. Field specimens were taken from the roof and analyzed for peel strength & surface condition of the rubber. At the time of the inspection, the application of the EPDM rubber membrane was considered to CoE personnel to be proceeding satisfactorily. Peel tests indicated that the field seams had low bond strengths in comparison to the strengths achieved by cleaned control specimens prepared on the roof using the same procedure and the same adhesive/rubber system. Both the field specimens and cleaned controls, for the most part, failed cohesively during peel testing. Unlike the cleaned controls, the adhesive layers of the delaminated field seams were found to contain numerous void areas. These voids may contribute to low strength of the adhesive layer, because they represent areas of little or no bond. In addition, because the control seams were cured primarily under lab conditions, a question was raiser whether the rates of adhesive cure in the field & lab were different. Scanning electron microscopy (SEM) analysis of uncleaned control specimens and also small areas of the field specimens that failed adhesively during peel testing showed platelet particles, typical of the release agent, present on the surfaces of both the rubber strip and the corresponding adhesive layer. This finding indicated that, in these cases, some peeling during testing occurred through the layer of release agent on the rubber surface.
This investigation was a limited study of seams in an EPDM rubber membrane of the roof of the new "Wheeled Vehicle Facility" building at Aberdeen Proving Ground, Maryland. The study was initiated at the request of the Corps of Engineers to provide data that could contribute to a database on the characterization of newly prepared field seams. The investigation was beneficial to NIST because it complemented laboratory research on test methods for evaluating seams of vulcanized rubber roof membranes. Field specimens were taken from the roof and analyzed for peel strength & surface condition of the rubber. At the time of the inspection, the application of the EPDM rubber membrane was considered to CoE personnel to be proceeding satisfactorily. Peel tests indicated that the field seams had low bond strengths in comparison to the strengths achieved by cleaned control specimens prepared on the roof using the same procedure and the same adhesive/rubber system. Both the field specimens and cleaned controls, for the most part, failed cohesively during peel testing. Unlike the cleaned controls, the adhesive layers of the delaminated field seams were found to contain numerous void areas. These voids may contribute to low strength of the adhesive layer, because they represent areas of little or no bond. In addition, because the control seams were cured primarily under lab conditions, a question was raiser whether the rates of adhesive cure in the field & lab were different. Scanning electron microscopy (SEM) analysis of uncleaned control specimens and also small areas of the field specimens that failed adhesively during peel testing showed platelet particles, typical of the release agent, present on the surfaces of both the rubber strip and the corresponding adhesive layer. This finding indicated that, in these cases, some peeling during testing occurred through the layer of release agent on the rubber surface.
Date
10/1989
10/1989
Author(s)
W Rossiter Jr; J Seiler Jr; P Stutzman
W Rossiter Jr; J Seiler Jr; P Stutzman
Page(s)
30
30
Keyword(s)
adhesive bonding; bond strength; EPDM rubber; field inspection; seams; scanning electron microscopy; SEM; surface; low slope roof
adhesive bonding; bond strength; EPDM rubber; field inspection; seams; scanning electron microscopy; SEM; surface; low slope roof