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3.2.5 Creep-Rupture Performance of Adhesively-Bonded Roofing Seams

Mark G. Vangel

James J. Filliben

Statistical Engineering Division, CAML

Walter J. Rossiter

Building Materials Division, BFRL

Adhesively-bonded EPDM (a rubber material) is widely used for low-slope industrial roofing. There are two main types of adhesive systems for seams on these roofs: a liquid adhesive, and several varieties of tape adhesive. Liquid adhesive is widely used, but it is volatile and relatively expensive to apply. An objective demonstration that tape adhesives are at least as reliable as the liquid will greatly increase the use of these adhesives. A consortium of NIST, professional roofing trade associations, and roofing adhesive manufacturers was formed, in part, to perform such a study.

The chosen measure of performance for the experimental seams is creep lifetime; i.e. the time-to-failure under a constant load. The figure illustrates mean lifetime as a function of load for three adhesive systems. These means are a summary of data on approximately 600 specimens, and the fitted curves are for a nonlinear model proposed by F. A. Bastenaire (ASTM STP 511, 1972) for fatigue in metals. This experiment suggests that, in terms of creep life, tape seam perform as well as adhesive seams.

The next phase of this experimental program, which will examine the effect of application parameters on creep life, has been designed and the testing is in progress.


Figure 17: Mean Creep-Rupture Lifetime of Adhesively-Bonded Seams

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Date created: 7/20/2001
Last updated: 7/20/2001
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