A Review of Rubberised Asphalt for Flexible Pavement Applications: Production, Content, Performance, Motivations and Future Directions

Abstract

The crumb rubber (CR) recycled from waste tyres could be a viable alternative in achieving green pavements that offer exciting new markets to global investors. Adding CR into flexible pavements enhances their performance and ensures environmental sustainability. This paper will discuss the production variables, CR sizes and contents, blending techniques, optimum bitumen contents, morphology, standard characteristics, rheological characteristics, mechanical performance, greenhouse gas emissions, energy consumption and life cycle cost. This review study found that compared to traditional asphalt mixtures, the CR-modified asphalts had superior performance and longer service life. However, the dearth of information on several factors in CR asphalt production, including greenhouse gas emissions, energy consumption and life cycle cost during recycling, causes many agencies in the global asphalt industry to continue employing costly, energy-consuming additives such as styrene-butadiene-styrene (SBS) instead of CR to enhance asphalt.

Use of Lignite Processing Products as Additives to Road Petroleum Bitumen

“…The main physical and mechanical properties of the original and modified bitumen were determined according to standardized methods. The following were determined characteristics, such as: penetration at 25 • C (P25) [27]; softening point (SP) [28]; elastic recovery at 25 • C (E25) [29]; and ductility (D25) were studied according to the methods described in the works [30,31]. Adhesion to the surface of the glass was assessed according to the Ukrainian standard test methods DSTU 9169:2021 [32], while adhesion to the gravel surface according to the DSTU 8787:2018 [33] The RTFOT method [34] was used for study the resistance of bitumen to technological aging.…”