Testing of blister propagation and peeling of orthotropic bituminous waterproofing membranes

Bridge decks are commonly subjected to harsh environmental conditions that often lead to serious corrosion problems, which are triggered by blisters under the hot mix asphalt bridge deck pavement with waterproofing membranes. These blisters are secretly evolving during weather exposure until often being detected too late. Formation of blisters under the waterproofing membrane is caused by a complex mechanism governed by bottom-up pressure and loss of adhesion. This paper primarily intends to adopt the analytical blister propagation energy approach for waterproofing membranes and compare it with adhesive fracture energy from standard peeling test methods, already described in the literature. Three different types of polymer modified bitumen membranes (PBM) were used for this purpose. The investigation includes a comparison between uniaxial and biaxial testing conditions for determining the modulus of elasticity of the membranes. Moreover, the influence of the displacement rate and temperature on the adhesive fracture energy in peeling tests is investigated. It was found that the biaxial modulus of PBM in the longitudinal and transversal direction is comparable with the uniaxial tension testing results in the main directions. In addition, it was observed that the ratio of longitudinal and transversal modulus of elasticity was similar. The energy calculated from tests with elliptical blister propagation showed a comparable value to the standard peeling fracture energy for similar types of PBM.