Performance Evaluation of Recycled-Concrete Aggregates and Reclaimed-Asphalt Pavements for Foam-Mix Asphalt Mixes

Mechanical foaming of bitumen is a popular technique employed to reduce the viscosity of binder for ensuring coating of aggregates at lower temperature. The potential of this technique is being utilized widely for producing sustainable reclaimed-asphalt pavement (RAP) inclusive mixtures, but usage of recycled concrete-aggregates (RCA) in foamed technology is very scanty. The present study is the first of its kind attempting to investigate the optimum proportion of hydrophobic RAP aggregates and hydrophilic RCA (separately as well as combined) for the preparations of foam-mix asphalt (FMA). It was observed that incorporation of RCA in FMA affects the quality of mixes but RCA inclusive FMA was found to qualify the stipulated specifications for pavement applications. From the present study, it is found that up to 20% RCA and 40% RAP proportions individually could be utilized for the preparation of foam mixes. Also, it is interesting to note that delayed hydration of residual cement grains could enhance the performance of FMA. Furthermore, 30% RCA coupling with 10% RAP was found to exhibit acceptable performance. The present study suggests that 0.1% fiber reinforcement could enhance the performance of the foam mixes considerably.