Evaluation of cold emulsified bitumen mixes using recycled con-crete aggregates as a base course

Abstract

The utilization of cold bituminous mixes in road construction is an environmentally and economically viable alternative to other stabilization processes. Besides, the incorporation of recycled materials into the cold mixes increases sustainability and decreases waste generation. The stabilization of Recycled Concrete Aggregates (RCA) with cement for pavement bases is a known one. However, the stabilization of RCA using bitumen emulsion is limited in nature. The present study evaluated the mechanical properties of the cold mixes prepared using RCA in different proportions (25%, 50%) with varying bitumen emulsion contents (5, 6, 7%). The compacted and cured samples are investigated for mechanical characteristics like density, Marshall Stability, Indirect Tensile Strength (ITS), Resilient Modulus, and permanent deformation. The dynamics of moisture evaporation and durability in terms of tensile strength ratios are studied. In the end, the vertical compressive and horizontal tensile strains of the pavement sections with bitumen emulsion stabilized bases are analyzed using IITPAVE software. The obtained results are compared using the critical strains calculated from the performance equations given by IRC (2018). It is noted that there is a decrease in the overall thickness of the pavement for the design traffic that varies from 5msa to 50msa. From this study, the base courses are recommended with bitumen emulsion treated RCA mixes, for traffic levels, up to 20 msa which would result in both -reductions in cost as well as the reduction in pavement overall-thickness. The present study also concluded that the optimum emulsion content of 6% does not show better resistance to permanent deformation. From the results, it is also suggested multi-variant mix-design criteria rather than a single indicative parameter.