Exploring the Self-Healing Capability and Fatigue Performance of Modified Bitumen Incorporating Waste Cooking Oil and Polyphosphoric Acid

Bitumen’s self-healing capability is critical to the bitumen industry’s sustainable development. This work attempts to examine the self-healing property and fatigue behavior of bitumen using waste cooking oil (WCO) and polyphosphoric acid (PPA) in bitumen modification. Different components of WCO were mixed with PPA and bitumen for the initial modification. The linear amplitude sweep (LAS) test was used to evaluate the fatigue behavior of the modified bitumen. To assess the extent of bitumen healing after a fatigue-healing test, evaluation indicators, including fatigue life recovery (FLR), modulus recovery (MR), and dissipated energy recovery (DER), were selected. Meanwhile, a radar chart was used to analyze the integrated performance of WCO/PPA (WP)-modified bitumen. Lastly, the SARA fractions were separated from the bitumen to evaluate the modification mechanism. It was observed that the inclusion of PPA and WCO enhanced fatigue behavior. For 2% PPA and an intermediate component (IC) of WCO, the fatigue life of the LAS prediction model showed extreme values, with an increase of 669% over virgin bitumen. Regardless of the PPA concentration, a considerable increase in FLR, MR, and DER was seen in the bitumen processed with IC compared to virgin bitumen. Additionally, as the healing time was extended, the increment in the virgin bitumen’s healing indicators was higher than that of the modified bitumen. SARA results indicated that adding PPA changes the bitumen from a soluble state to a gel state. An innovative approach has been proposed to promote sustainable development within the bitumen industry.

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