Published: Jan 1990
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Adhering SBS-modified asphalt roll roofing membranes with hot asphalt, using a propane torch to weld the SBS membrane to its substrate, and attachment of the SBS membrane with solvent-based bituminous adhesives are some of the major application techniques practiced successfully in the roofing industry. Integrity of the overlapping regions of placed membranes is of great concern, as this is seen as the most vulnerable route for moisture migration in a constructed membrane. The objective of this paper is to investigate and discuss the impact of each mode of application on the ability of the constructed SBS membrane overlap to provide adequate waterproofing and membrane lap strength. Results indicate that the energy to fail well-constructed laps in shear, regardless of mode of manufacture, approaches that of the energy to fail the individual membranes being adjoined. Cyclic fatigue results indicate that repeated load-bearing capability at 0°F (-17.8°C) without loss of waterproofing is possible for the three types of application methods. GPC shows that the torching process can be controlled to minimize SBS degradation. The results of all testing are dependent on application variables for each mode of manufacture. An understanding of the limitations to, as well as the requirements for, obtaining satisfactory performance has been developed.
styrene-butadiene-styrene (SBS) block copolymer, network, KRATON, ®, thermoplastic elastomer, modified bitumen roll roofing, lap, lap shear strength, t-peel strength, Type III asphalt, propane, gel permeation chromatography (GPC), fatigue
Associate research engineer, Shell Development Co., Houston, TX