Rheological analyses of binders modified with triple combinations of Crumb-Rubber, Sasobit and Styrene-Butadiene-Styrene

Abstract

The development of polymer-modified asphalt (PMA) has been a widely used technique by many researchers. Moreover, further modification of PMA binders has generated interest due to possible improvements in performance and cost. In this regard, Sasobit wax has been an alternative to reduce costs in Crumb-Rubber (CR) and Styrene-Butadiene-Styrene Copolymer (SBS) binders. However, there is little detail on the rheological behaviour of CR-SBS-Sasobit triple-modified samples for failure and damage resistance properties. Therefore, this study shows various properties of binders with triple modification of CR-SBS-Sasobit at different dosages. For this purpose, the development of single, double and triple modifications has been proposed to be tested by Multiple Stress Creep Recovery (MSCR) for permanent deformation. In the case of radial cracking and thermal cracking, it is evaluated by linear amplitude sweep test (LAS) and binder creep energy test (BYET). The results indicate that a CR-SBS combination in single or double addition achieves good thermal stability and behaviour. However, a higher elasticity is achieved in the case of a triple modification with CR-SBS-Sasobit. Specifically, Sasobit achieves 67% and 28% reduction in the cumulative deformation of MSCR for a variation of 40–80 °C, respectively. Concerning fatigue life (Nf), it is shown that CR-SBS modifications do not always acquire higher Nf than single modifications. However, adding Sasobit in triple modifications increases these values, generating bitumen with higher strength. It is also shown that adding Sasobit is a viable modifier in yield, even increasing the yield energy (Er) for samples with equal CR-SBS and reducing the percentage of SBS in the sample.