Moisture sensitivity of interlayers between conventional and porous asphalt mixes

The use of geocomposites obtained combining bituminous membranes with reinforcing geosynthetics represents a promising option for asphalt pavement application. Thanks to their waterproofing effect, such geocomposites could be successfully used also underneath porous surface layers as an alternative of bituminous tack coat. In this sense, one of the major issue related to the use of geocomposites at the interface between porous surface layers and binder courses is the prolonged contact with drained rainfall water. Given this background, a specific research study was carried out in order to evaluate the moisture sensitivity of interlayers positioned between traditional dense graded asphalt concretes and porous asphalt concretes. Particularly, two geocomposite materials produced combining an elastomeric membrane with a polyester textile and a fiberglass grid, respectively, were investigated along with a traditional reference interlayer obtained by applying hot polymer modified asphalt at the interface. In order to evaluate moisture sensitivity of such interlayers, shear tests were carried out in both dry and wet conditions on double- layered samples prepared in the laboratory. Experimental results showed that the prolonged action of the water did not produce loss of performances of studied interlayers in terms of interface shear strength.