Exploring production and performance of popular bio-oil modified asphalts: a state-of-the-art research review

Asphalt modification is one of the effective techniques to enhance the performance of flexible roadways exposed to heavy traffic and high-temperature variations. Among these methods, the utilization of bio-oils has gained global acclaim due to their compatibility with asphalt and subsequent performance improvements. This review paper primarily focuses on the current state-of-the-art of eight extensively studied bio-oil modified asphalt using: (i) Soybean Oil (SBO), (ii) Algae Bio-oil (ABO), (iii) Sunflower Oil (SFO), (iv) Castor Bean Oil (CBO), (v) Wood Bio-oil (WBO), (vi) Palm Oil (PO), (vii) Tall Oil (TO), and (viii) Swine Manure Bio-oil (SMB). The first part of the review comprises a discussion on the physio-chemical characteristics of eight bio-oils utilized in asphalt modification, the second part includes blending methodology, production, and performance characterization of bio-oil modified asphalts, the third part focuses on a comparative analysis of bio-oil modified asphalt based on production and performance characterization. The field performance of bio-oil modified asphalt pavements, its environmental impacts, and the challenges associated with bio-oil modification are discussed in the fourth and fifth sections, respectively. Given the global underutilization of bio-asphalt development, mix design, and construction methodologies, this paper serves as a reference, presenting insights into the benefits and impediments of bio-oil pavement enhancement.