Development of a peel test procedure for adhesive applied roof systems

Abstract

Roofing systems are an important component of the building envelope. Though the Adhesive Applied Roof Systems (AARS) are gaining popularity in North America, systematic review of the existing national and international standards revealed that there is no proper testing procedure established to quantify the peel resistance of AARS. The objective of the present study is to develop a peel testing procedure based on systematic laboratory investigations. Specimens (6 in. x 6 in. or 152 mm x 152 mm) composed of insulation and cover board were adhered together by applying cold adhesives. To represent the realistic conditions of the field construction, specimens were prepared using components from four industrial sources. Specimens were then subjected to a peeling force at two different locations with various peel angles ranging from 7.5° to 45° to simulate the blister shape, that can occur on AARS under several wind action. Additional specimen sizes were also tested for selected combinations to evaluate the size effect. A total of 378 specimens with various physical parameters were constructed, cured for 28 days and tested using an Instron machine at a constant loading speed. For all cases, the failure load as well as the failure mode was recorded. Data analysis indicates that the failure load decreases as the peel angle increases, though it increases with the sample size. Generalized curves reflecting the peel resistance versus peel angle and the sample size are presented. Failure mode analysis identified the weakest link of the AARS samples under simulated wind induced peeling force. Based on the experimental investigation, a standard peel test method was drafted. This standard has an essential importance for the evaluation of AARS performance under wind-induced peel forces, which will be applicable to the new roofing assemblies as well as the existing roofing assembly to be replaced or recovered.