ABSTRACT
This study reviews factors influencing the in-service performance of single-ply roofing systems and introduces new test methods for the characterization of polymer-modified bituminous roofing membranes (PMB). The most commonly used PMB roofing membranes, e.g. Atactic Polypropylene (APP)-modified bitumen and Styrene-Butadiene-Styrene copolymer (SBS)-modified bitumen, were studied.
The factors influencing lap separation, crazing, blistering, and durability of membrane were discussed by reviewing articles. New test methods, such as Chromatography, Microscopies, and Thermal Analyses were also discussed.
Degradation in polymer during the manufacturing process of the roofing membrane was studied with High Performance Gel Permeation Chromatography. The degradation in polymer resulted in decreased molecular weight. Using High Pressure Liquid Chromatography, the chemical compositions of bitumen, influencing the durability, were proportioned. Using Thermogravimetry, PMB was proportioned into pyrolyzable organics, combustibles, and residue. Using microscopies, the dispersity of PMB was studied for evaluation of the compatibility of polymer/bitumen system. Microscopy was also used to study a membrane structure, e.g. reinforcement, impregnation, and filler size.
It was concluded that these tests can supplement conventional test methods for characterizing PMB used in roofing applications. Roofing systems using PMB membranes act different from the conventional built-up roofing system and therefore these methods need to be standardized. The results obtained may have significance in the satisfactory service life design of the roofing system.
