Investigations on Stone Matrix Asphalt Mixes Containing Recycled Concrete Aggregate Treated with Nanosilica

Abstract

The present work is an attempt to explore use of recycled concrete aggregate (RCA) to replace natural aggregates (NA) in a sustainable way in stone matrix asphalt (SMA) mixes used as a rut resistant bituminous layer. Based on several initial trials, a modified pretreatment procedure has been developed, which involves mixing of RCA with 8% (by weight) nanosilica modified bitumen emulsion solution followed by 24-h curing. The treated RCA (TRCA) has been used as coarse aggregate completely replacing the coarse NA, with two different types of bitumen namely, VG 30 and VG 40 bitumens for preparation of SMA mixes. Marshall method was used to determine optimum bitumen content (OBC) of the respective mix type. The pertinent performance characteristics such as stone-on-stone contact, drain-down, Marshall parameters, indirect tensile strength, moisture susceptibility, resilient modulus and rutting potential have been addressed for various SMA mixes prepared at respective OBCs. It is concluded that TRCA as aggregate and VG 40 bitumen as binder in SMA mix contributed to the best results in terms of various performance parameters considered.