## 1 Introduction  
With the rapid development of highway networks worldwide, asphalt pavements in many countries have entered the maintenance phase [1, 2, 3]. As an emerging green maintenance technology, hot-in-place asphalt pavement recycling enables 100% reuse of existing pavement materials while addressing road distresses, effectively achieving energy conservation, emission reduction, and cost efficiency in road maintenance projects [4, 5, 6].  
This technology has consequently garnered extensive research and application. A critical feature of hot-in-place recycling is its high reclaimed asphalt pavement (RAP) content, leading to a substantial proportion of aged asphalt in the total binder system. To restore the rheological properties of aged asphalt and ensure effective integration with new asphalt, the addition of reclaiming agents becomes essential. As the core material determining recycled pavement quality, reclaiming agent performance has thus become a research frontier in the field.  
Current research categorizes reclaiming agents by their base oil sources: petrochemical oils, vegetable oils, and waste extract oils. Petrochemical oils (including aromatic, paraffin, and napththenic oils) dominate traditional regenerants. While studies demonstrate their effectiveness in reducing asphalt stiffness and enhancing low-temperature cracking resistance [7, 8], their fatigue resistance performance remains controversial. Moreover, these oils exhibit significant volatility at temperatures exceeding 180 \({}^{\circ}\)C, limiting the RAP content to \(\leq\)30% [9, 10]. Vegetable oils, composed of unsaturated fatty acid-glycerol compounds, have been developed from soybean, corn, and rapeseed oils [11, 12, 13, 14], with optimal dosages around 5-6%. These bio-based agents demonstrate superior low-temperature crack resistance, fatigue resistance, and high boiling points. Waste extract oils encompass waste engine oil and waste vegetable oil. Although waste engine oil requires additives to improve viscosity, stability, and cleanliness due to compositional complexity [15, 16], waste vegetable oils (primarily from fast-food fryers) effectively restore aged asphalt's rheology through their small molecular weights [17, 18, 19]. Plant-derived waste oils, rich in fatty acid methyl esters, exhibit strong lipophilicity and permeability [20, 21, 22], presenting substantial market potential.  
Existing studies suggest that while petrochemical-based regenerants show good asphalt compatibility, their high cost and poor high-temperature stability limit applications. In contrast, vegetable-oil-based agents attract growing attention due to abundant resources, cost effectiveness, and high-temperature stability during construction. However, regeneration efficacy varies significantly across vegetable oil types, necessitating further exploration in agent formulation.  
To address these gaps, this study develops a novel vegetable oil regenerant through the dehydration and filtration of waste palm oil blended with plasticizers and anti-aging agents, using petrochemical-based regenerants as benchmarks. The research methodology involves three phases: (1) determining optimal dosage via dynamic shear rheometer and bending beam rheological tests on aged asphalt; (2) analyzing viscoelastic effects on asphalt mixtures through uniaxial dynamic modulus tests and trabecular bending creep tests; (3) evaluating road performance via rutting resistance, trabecular bending, freeze-thaw splitting, and immersion Marshall stability tests. The findings provide theoretical guidance for expanding the selection and application of asphalt reclaiming agents.