Jagadeesh Gopalam’s research while affiliated with GMR Institute of Technology and other places

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.

The use of different filler materials is one of the effective techniques adopted to improve pavement quality and performance.The main purpose of this study is to quantify the influence of filler type on the performance of dense graded bituminous mixes containing recycled concrete aggregate (RCA).This RCA is replacing the coarse portion of the conventional natural aggregates (NA). In this present experimental investigation, the dense bituminous macadam (DBM) mixes according to the relevant Indian specifications are compacted using four different types of fillers, such as cement, stone dust, fly ash and carbon black and conventional VG 30 as binder. Eight different sets of Marshall samples are prepared using RCA and NA representing the coarse aggregate fraction and either of the above four binders. Different mixes thus prepared are evaluated in terms of their Marshall parameters, indirect tensile strength, moisture susceptibility characteristics (tensile strength ratio and retained stability) and resilient modulus. From the experiment conducted in the laboratory, it is found that all the mixes, in general satisfy the requirements in terms of Marshall and moisture susceptibility characteristics. Considering all engineering properties studied the mixes with NA and carbon black (CB) as filler materialofferedhigher results comparable with other mixes. However, the mixtures prepared with RCA also offered a promising result compared to mixtures made with NA.