Description
Unlocking the potential of lignin in asphalt-rubber: An attempt to synergize bio-based industrial waste with scrap tires
Renuka Wagh1, Harmandeep Kaur2, and Krishna Prapoorna Biligiri3,*
1Graduate Researcher, Department of Civil & Environmental Engineering, Indian Institute of Technology Tirupati, Andhra Pradesh, 517619, India; Email: ce23m408@iittp.ac.in
2Doctoral Research Scholar, Department of Civil & Environmental Engineering, Indian Institute of Technology Tirupati, Andhra Pradesh 517619, India; Email: ce22d502@iittp.ac.in
3,*Corresponding Author, Professor, Department of Civil & Environmental Engineering, Indian Institute of Technology Tirupati, Andhra Pradesh 517619, India, Tel: +91-877-2503157; Email: bkp@iittp.ac.in
ABSTRACT
The increasing pace of roadway construction and traffic volume has led to an exorbitant demand for asphalt binder, a non-renewable petroleum-based material. In this regard, asphalt-rubber (AR) binder and mixtures have historically been developed as durable, cost-effective, and sustainable pavement solutions that align with sustainability principles, circular economy, and waste management strategies. Lignin, a natural biopolymer from bio-refinery and pulp & paper industries has been widely utilized in cement as a superplasticizer, carbon fiber production, water purification, bio-based aromatics, biosensors, drug delivery, bioplastic and nanocomposites. Despite the well-established benefits of AR products and the potential of lignin as a sustainable alternative, their combined use in asphalt binders remains largely unexplored. Therefore, the major objective of this study was to investigate compatibility of lignin and AR together in asphalt modification and develop a set of novel lignin-modified AR binders and mixtures through rheological and mechanical performance assessment. The scope included: (i) preparation of different combinations of lignin and crumb rubber (CR) in modifying the base asphalt binder using the wet process, (ii) optimization of dosages through basic and advanced binder tests, and (iii) preparation of lignin-modified AR gap-graded asphalt mixtures to assess the performance of the two modifiers in the mixtures through the state-of-the-art material characterization tests. The results indicated that incorporating CR and lignin to modify the asphalt mixtures enhanced rutting, fatigue, and moisture resistance. Overall, it is envisioned that this research study will help demonstrate the synergistic use of lignin and CR in enhancing the asphalt binder performance in concert by promoting waste valorization and reducing dependence on petroleum-based products.
KEYWORDS: Crumb rubber, bio-asphalt binders, kraft lignin, wet process, performance grade, gap-graded aggregate gradation, mechanical performance, sustainability, valorization, circular economy.
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