EFFECT OF PROCESSING TEMPERATURE VARIATION ON STORAGE STABILITY OF TIRE RUBBER MODIFIED BINDERS

Abstract

Tire Rubber Modified Binders (TR-MBs), produced through wet process and used worldwide (e.g. asphalt rubber), have been demonstrated to provide various benefits to pavements and, moreover, represent a good opportunity for recycling tire rubber. However, this technology is still struggling to be fully adopted in Europe, mainly because of the poor stability of TR-MBs during high temperature storage, which leads to high initial costs in modifying existing asphalt plants. No-agitation TR-MBs (also known as terminal blends) are proving to be a great option and their development could also be the key to spreading the use of tire rubber in paving applications in Europe. This paper aims to enrich this field of research by presenting the results of a study focused on the compatibility of tire rubber-bitumen blends as well as on the effect of processing temperature variation on storage stability of TR-MBs. The experimental program was carried out by a preliminary selection of materials, followed by the production of the TR-MBs, via practical laboratory protocols. A continual comparison between two commercially used SBS-MBs, with high and medium levels of modification, and the TR-MBs produced, helped to understand the effect of varying the selected processing conditions on binder properties. The results showed that an accurate binder design is fundamental in order to obtain high performance binders and to improve compatibility of TR-MBs. Moreover, the study highlights that dynamic mechanical analysis (DMA) is a suitable technique to assess the storage stability of modified binders.