Mechanical Performance of Liquid-Applied Roof Waterproofing Systems

This study characterizes the mechanical performance of unreinforced and reinforced liquid-applied roof waterproofing systems (LARWS) based on several polymer types and links it to the pedestrian accessibility of roofs. The influence of the thickness and reinforcement on the system's performance was assessed on free-film samples of cementitious, acrylic, liquid silicone, liquid rubber, and polyurethane-based systems. Tensile properties and resistance to dynamic and static indentation were determined. Further verification of fitness for intended use was assessed with watertightness and flexibility at low-temperature tests. The type of product was the most influential parameter on the mechanical performance of LARWS. The cementitious and the polyurethane-based systems had a much higher resistance to indentation than all the others, which were, at best, only fit for nonaccessible roofs. The use of internal reinforcement can improve the resistance to dynamic or static indentation. Using an extra coat of the product yields a higher resistance only to dynamic indentation. Deformability or stiffness could not be directly linked to a system's resistance to indentation. A flexibility test at a low temperature (-5 degrees C) found that the mechanical performance of LARWS was not severely affected by those conditions. (C) 2013 American Society of Civil Engineers.