An important factor affecting the performance of seams of EPDM membranes is their ability to remain bonded over the membrane's expected service life. Time-to-failure tests provide a means of characterizing the behavior of joints under constant load over time.

Note 1-Table 1 is based on the results of an industry government consortium study on creep-rupture resistance (time-to-failure) of EPDM adhesive joints. ^, Referral to Footnotes 5 and 6 provides typical time-to-failure data, developed under the conditions in Table 1, for EPDM joints fabricated in the laboratory with nonreinforced EPDM roof membrane material, butyl-based tapes, and liquid adhesives. It is noted that the peel load specified in this practice is 9.8 N [2.2 lbf]. The peel load under which the tests described in Footnotes 4 and 5 were conducted was 9.3 N [2.1 lbf]. A load of 9.8 N [2.2 lbf] corresponds to 1 kgf [2.2 lbf], and dead weights of 1-kg [2.2-lbm] mass are available through laboratory equipment supply houses. Similarly, a load of 29.4 N [6.6 lbf] corresponds to a dead weight of 3-kg [6.6-lbm] mass.

Time-to-failure tests complement other mechanical tests such as strength for characterizing joints of EPDM roof membranes, and can be incorporated in specifications for adhesives for joining EPDM roof membrane material.

This practice, which is specific to EPDM joints, complements Test Method D5405 that provides general requirements for the preparation and creep-rupture testing of joints fabricated from any nonbituminous organic roof membrane material.

Laboratory experience in conducting time-to-failure tests of joints EPDM roof membranes has shown that specimens are less creep-resistant under peel loading than under shear loading. Consequently, the majority of the tests stipulated in this practice are performed under peel loading.

This practice does not develop time-to-failure data on all environmental conditions to which EPDM adhesive seams can be subjected in service.