Alternative Methodologies to Evaluate Storage Stability of Rubberised bitumens

Tyre Rubber Modified Binders (TR-MBs), produced through the McDonald wet process and used worldwide (e.g. asphalt rubber), have demonstrated various benefits to pavements and, moreover, they represent a good opportunity for recycling tyre rubber. However this technology is still struggling to be fully adopted in Europe. One of the reasons is their poor stability during high temperature storage, which leads to high initial costs due to usage of specialised equipment. No- Agitation (storage-stable) TR-MBs is proving to be a great alternative and its development could also be the key to increase the use of tyre rubber in paving applications in Europe. This paper presents the results of a study which focuses on investigating conventional and alternative methodologies to evaluate the storage stability of TR-MBs. Results have shown that an accurate binder design is fundamental to improve compatibility of TR-MBs. Furthermore, the study highlights that Dynamic Mechanical Analysis (DMA) and X-Ray CT scans are very suitable techniques to control the compatibility of tyre-rubber bitumen blends leading to the development of storage-stable TR-MBs.