Evaluation of the Properties of Bituminous Binders Modified with Recycled Waterproofing Membranes (RWM)

Waterproofing membranes (WM) are mainly composed of polymer-modified bituminous mastic (with filler addition) and reinforcement. One side is exposed to air, and the external layer is an anti-adhesive layer (covered with mineral chips). Because of ageing and deterioration, WM are removed from roofs or bridge decks and landfilled. Nowadays, only a few membrane producers are equipped with recycling plants to recycle WM (RWM) into new products, by reintroducing them into the production process. However, the presence of highly modified bitumen in RWM provides an interesting opportunity to recycle them for use in asphalt pavement materials. Hence, our experiment evaluated the introduction of RWM into plain bitumen and investigated the obtained mechanical properties. The study involved two types of RWM according to the polymer type contained: styrene–butadiene–styrene (RWMSBS) and atactic polypropylene (RWMAPP). The study was conducted at the binder scale, and a large spectrum of rheological properties was analysed. In general, the addition of up to 30% of RWM in plain bitumen confers higher stiffness and better rutting performance, penalizing at the same time the minimum service temperature.