# Research on Mechanical Performance of Porous Asphalt Mixture with High-Viscosity Modified Asphalt
## 1 Introduction  
By the end of 2020, the total length of roads in China had reached 5.35 million kilometers [1]. However, the rapid increase in traffic volume, along with the higher frequency of axle overloading and extreme weather events, has introduced a series of new challenges for road construction and maintenance [2]. Inadequate skid resistance of road pavements has been identified as a significant contributing factor to road traffic accidents [3]. Therefore, improving the skid resistance of pavements is an urgent issue for the current road construction and maintenance industry [4]. Porous asphalt pavement is a widely used functional pavement. It can extend the service life of the pavement, improve its anti-skid performance, and ensure the safety and comfort of driving [5]. Under the repeated action of vehicle loads, water in the voids of the mixtures continuously flushes the interface between the asphalt and the aggregates. This reduces the bonding effect of the asphalt binder on the mineral materials, leading to pavement loosening, particle loss, and other issues. On the other hand, traditional modified asphalt cannot meet the application requirements of porous asphalt layers, which significantly affects the road surface function and endangers driving safety [6; 7; 8]. Recent advancements in polymer-modified asphalt technologies have focused on improving the mechanical properties of porous asphalt mixtures [9]. Among these, styrene-butadiene-styrene (SBS) modified asphalt has become a benchmark material due to its balanced viscoelasticity [10]. However, conventional SBS modifiers exhibit limitations in maintaining high-temperature stability under heavy traffic conditions, with viscosity reductions exceeding 35% at 60 \({}^{\circ}\)C. This degradation directly impacts the cohesion-aggregate interlock mechanism, leading to premature traveling and reduced service life [11]. High-viscosity modifiers (HVMs) have emerged as a potential solution, yet existing formulations often compromise low-temperature flexibility or require complex production processes [12]. High-viscoelastic modifier raw materials, including antioxidants, can improve the heat and oxygen aging resistance of modified asphalt. Stabilizers can prevent the decomposition and aging of modified asphalt and enhance its stability. Therefore, the content of antioxidants and stabilizers has a significant impact on the effectiveness of high-viscoelastic modifiers. The Ohio Department of Transportation designed an ultra-thin wear layer mix with two gradations, A and B. Both mixtures used high-viscosity modified asphalt as the binder. Type A mixtures, similar to asphalt sand, were suitable for roads with lower traffic volumes, while Type B mixtures were designed for roads with higher traffic volumes [13]. [PERSON] et al. [14] investigated the relationship between the viscosity of high-viscosity asphalt and the water stability properties of porous asphalt mixtures. Their research indicated that increasing the asphalt dosage within a certain range positively affected the water damage resistance of porous asphalt mixtures. To reduce the cost of drainage asphalt pavement in China, further study is needed on high-viscosity modified asphalt and high-viscosity additives tailored to China's heavy traffic conditions. The scientific novelty of this study lies in its development of a novel HVM through strategic molecular design. Unlike previous approaches that solely focus on viscosity enhancement, our modifier incorporates reactive elastomeric terpolymers that form covalent bonds with asphalt components. This chemical interaction not only increases zero-shear viscosity magnitude compared to conventional SBS-modified asphalt but also maintains penetration index values within the optimal range for thermal cracking resistance [15]. This study focuses on the technological development and engineering application of a novel high-viscosity modifier (HVM). Through systematic experimental investigations on asphalt binders and mixtures, three primary objectives are pursued.