Rubber-Plastic Conglomerates as Sustainable Aggregates: Assessment of Asphalt Interaction and Swelling Dynamics

Description

Rubber-Plastic Conglomerates as Sustainable Aggregates: Assessment of Asphalt Interaction and Swelling Dynamics

Neetu Gopakumar

¹Doctoral Research Scholar, Department of Civil & Environmental Engineering, Indian Institute of Technology Tirupati, Andhra Pradesh 517 619, India. ce22d505@iittp.ac.in 

Krishna Prapoorna Biligiri

^2*Corresponding Author, Professor, Department of Civil & Environmental Engineering, Indian Institute of Technology Tirupati, Andhra Pradesh 517 619, India. bkp@iittp.ac.in

ABSTRACT: The major objective of this study was to assess the compatibility of rubber-plastic conglomerates developed through modification of tire-derived aggregates (TDA) using waste plastics and understand the swelling dynamics of the modified asphalt mixture through an ingenious “semi-dry approach” aimed at applications in the subsurface layers of the pavement system. The scope of the study included: (i) development of modified tire-derived aggregates (MTDA) utilizing three types of waste plastics encompassing high-density polyethylene (HDPE), polyethylene terephthalate (PET), and polypropylene (PP), (ii) assessment of compatibility and interaction effects of MTDA with asphalt binder using thermochemical characterization methods such as thermogravimetric analysis (TGA) for thermal stability, Fourier-transform infrared spectroscopy for functional group identification, and Brunauer–Emmett-Teller analysis for surface area and pore volume distribution, and (iii) investigation of swelling dynamics by incorporating 10% MTDA by weight of the fine aggregates in asphalt mixtures through evaluation of dimensional changes after compaction. The findings revealed that all types of MTDA were thermally stable and had distinct surface properties compared to the unmodified TDA, indicating their potential for effective integration with the asphalt binder. Further, the compatibility assessment demonstrated that incorporation of HDPE, PET, and PP improved interaction between the modified aggregates and the asphalt binder, enhancing the overall cohesive attributes of MTDA. Additionally, swelling evaluation of MTDA-modified asphalt mixtures exhibited that replacement of MTDA in asphalt mixtures significantly reduced the swelling potential of the mixtures, with lower swelling (about 50-70%) of MTDA-based mixtures compared to the conventional rubberized asphalt (RA) materials. It is envisioned that this study will contribute to a sustainable waste management strategy by integrating recycled plastics and TDA into the asphalt mixtures, thus assisting in the enhancement of pavement performance, alleviation of waste accumulation, and importantly, conservation of natural resources.

KEYWORDS: Rubberized asphalt, waste plastics, tire-derived aggregates, sustainable aggregates, high-density polyethylene, polyethylene terephthalate, polypropylene.