The inherent properties of hard asphalt binder give it both mechanical and economic benefits, rendering it a naturally advantageous material for preventing permanent deformation at higher temperatures. However, its poor resistance to thermal and fatigue cracking limits its application in the paving industry. This study aimed to improve the low-temperature and fatigue performance of hard asphalt binders by using the newly developed vegetable oil-based sub-epoxidized rapeseed oil (SERO). Two SEROs with epoxidation degree of 49.1% and 98.1% were synthesized through an oxidation reaction, respectively. Subsequently, the microstructural characteristics of SEROs were examined by Fourier transform infrared spectroscopy (FTIR) and Hydrogen nuclear magnetic resonance tests. The anti-oxidative aging properties of SERO modified hard asphalt binders were investigated through the utilization of mass loss and aging index. Additionally, the comprehensive rheological properties of SERO modified hard asphalt binders were explored via dynamic shear rheometer and bending beam rheometer tests. Furthermore, the modification mechanism of SERO on hard asphalt binders was confirmed through the quantitative analysis using the FTIR test. The findings suggested the improvement in anti-volatilization and anti-oxidative aging performance of bio-modified hard asphalt binders, which was positively related to the epoxidation degree of SERO. A notable softening effect of SERO on the hard asphalt binders was observed, which enhanced their resistance to thermal and fatigue cracking at lower and intermediate temperatures. The epoxy groups within SERO engaged in ring-opening reactions, forming a new oxygen bridge bond by combining with the unsaturated double bond presented in the asphalt. Consequently, this process resulted in the formation of cross-linked structures within bio-modified hard asphalt binders, thereby enhancing the elasticity. Notably, this phenomenon was most conspicuous in the SERO-H modified 50# binder. Finally, the environmental and economic assessment of SERO modified hard asphalt binders were conducted by the techno-economic method and the emission factors technique. The data revealed that the production of one ton of SERO modified hard asphalt binders could reduce the production costs by about 30%, energy consumption and CO 2 emissions by around 20% in contrast to styrene–butadiene–styrene block copolymer modified asphalt binders. Hence, the substantial economic and environmental advantages make SERO an attractive bio-renewable additive for sustainable pavements.
Hard asphalt binder is regarded as a favorable option in comparison to polymer-modified asphalt for rutting due to the benefits of cost-effectiveness and extreme stiffness behavior. However, its inherent poor ability to withstand fatigue damage and thermal cracking restricts its applications as a pavement material . This study aimed at enhancing the low-temperature and fatigue performance of hard asphalt binders with newly-developed rapeseed oil (RO)-based derivatives. Two rapeseed oil -based derivatives of epoxidized rapeseed oil (ERO) and acrylated epoxidized rapeseed oil (AERO) were laboratory synthesized through oxidation and ring-opening grafting reactions, respectively. Fourier transform infrared spectroscopy (FTIR) and Hydrogen nuclear magnetic resonance ( 1 were conducted to confirm the successful synthesis of derivatives. Mass loss, aging index, performance grading, temperature-frequency sweep, linear amplitude sweep and bending beam rheometer test were employed to assess the modified effects of rapeseed oil-based derivatives on two types of hard asphalt binders. To further explore the differences between RO and derivatives, the properties of modified hard asphalt binders using two derivatives were compared against the performance of RO-modified hard asphalt binders. With the additional RO, ERO, and AERO, the modified hard asphalt binders had significantly improved the resistance to thermal cracking and fatigue damage at low and intermediate temperatures, respectively. RO was found to have the most positive effect on the stress relaxation and the most adverse effect on the stiffness of hard asphalt binders. While, ERO- and AERO-modified hard asphalt binders had shown better antioxidative and anti-aging performance than that of RO-modified hard asphalt binders. Additionally, AERO-modified hard asphalt binders were noticed to have improved the elasticity of hard asphalt binders owing to the formation of a polymer elastic network. According to the study, two rapeseed oil-based derivatives had shown great potential as green and sustainable asphalt modifiers on the improvement of thermal and fatigue cracking resistance with the minimal adverse effect on anti-rutting performance of the hard asphalt binders. The test results revealed that the rapeseed oil-based derivatives modified hard asphalt binders could be employed in various pavement applications with great economic and sustainable benefits.
Traditional hard asphalt, due to its low cost and excellent mechanical properties, is considered a favorable material for resisting permanent deformation under high-temperature conditions. However, its limited stress relaxation ability at medium and low temperatures significantly impairs its capacity to meet the cracking resistance requirements. To address the limitation, this study synthesized three green and sustainable bio-renewable additives derived from high oleic rapeseed oil. These additives aimed to improve the performance of hard asphalt at medium- and low-temperature conditions, thereby broadening its potential for application in green and low-carbon construction practices. Bending Beam Rheometer (BBR) tests were conducted to determine the critical low-temperature difference (ΔT c ) to evaluate the thermal cracking resistance of bio-modified hard asphalt. The effects of the bio-additives on fatigue cracking resistance of hard asphalt were investigated using rheological indices, crossover frequencies, Glover-Rowe (G-R) parameters, and Linear Amplitude Sweep (LAS) tests. The results indicated that bio-additives effectively alleviated the stress in hard asphalt and reduced the asphalt’s susceptibility to thermal cracking by improving the flexibility and stress relaxation of the hard asphalt at low temperatures. Furthermore, the bio-additives substantially improved the ductility and toughness of hard asphalt at intermediate temperatures by lowering its strain sensitivity and increasing its fatigue cracking resistance. Additionally, the high oleic rapeseed oil-based derivatives notably reduced hard asphalt binder’s cracking induced by aging. Among the three bio-additives, acrylated epoxidized high oleic rapeseed oil (AEHORO) and epoxidized high oleic rapeseed oil (EHORO) were noticed to exhibit the most significant improvements in thermal cracking resistance and anti-aging properties, demonstrating superior load-bearing capacity at low temperatures. Overall, the developed bio-additives significantly improved both the thermal cracking and fatigue damage resistance of traditional hard asphalt, thus expanding its applications in pavements for various regions.
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