Investigation on cohesion and bitumen/aggregate affinity of rubberized porous asphalt by dry process

The purpose of this study is to investigate the effect of crumb rubber on the performance characteristics of porous asphalt mixture in terms of binder/aggregates affinity and mixture cohesion. The recycling of scrap tires in asphalt pavements appears as an important alternative providing a large-scale market. The characteristics of bitumen are very important with regard to service life of porous asphalt pavement. The experimental study consists of two main steps: Step I, sample fabrication by Marshall method with and without crumb rubber (worth mentioning that the mix design was performed in the first stage of the research.) and Step II, was dedicated to testing procedure in in order to investigate on performance characteristics of the porous asphalt mixtures. During the experimental work in accordance to the Cantabro weight loss, to obtain the grade of cohesion between the aggregate and bitumen, the Rolling Bottle Test (RBT) in order to investigate on the effects of CR on bitumen affinity have been conducted and the results were compared. The experimental tests result which has been performed in the laboratory of the University of Bologna shows that adding CR in both Cantabro weight loss and RBT could enhance the cohesion and affinity properties, which represents higher resistance to early raveling and stripping.