Influence of binder type on performance of dense bituminous mixture prepared with coarse recycled concrete aggregate

Conventional stone aggregates are becoming scare and costly because of huge infrastructure activities going on since last three decades in India. On the other hand, wastes such as that resulting from old concrete constructions are abundantly available. Many attempts have already been made to utilise these wastes referred to as recycled concrete aggregate (RCA) in various constructions including in bituminous paving layers. All types of bituminous binders commonly used in paving mixes in India may not be compatible with RCA. This experimental study aims to study the influence of binder type on the performance of dense graded bituminous mixtures containing RCA replacing the coarse fraction of conventional stone aggregates. In order to achieve this main objective, dense bituminous macadam (DBM) mixtures as per the relevant Indian specifications were prepared using three different types of bituminous binders commonly used in India, namely conventional VG 30 and VG 40 bitumens, and crumb rubber modified binder (CRMB). Separate Marshall samples were prepared using RCA and natural aggregate (NA) and either of the above three binders. As per the main scope of this study, the mixtures thus prepared were evaluated in terms of their engineering properties such as Marshall characteristics, indirect tensile strength, moisture susceptibility characteristics, resilient modulus and rutting resistance. It is observed that all mixtures considered in this study, in general satisfy the requirements in terms of Marshall and moisture susceptibility characteristics. Considering all engineering properties studied, the CRMB/VG40 bitumen offer superior and satisfactory results for mixtures containing either NA or RCA, with NA showing slightly better result as compared with RCA in the mixtures.