## 1 Introduction  
Traffic accidents, injuries, and fatalities continue to pose significant challenges for state Departments of Transportation (DOTs) and local highway agencies, both in terms of human lives and economic costs. Road safety extends beyond encouraging safe driving; proper pavement surface maintenance is critical to preventing accidents and reducing their severity [1]. High Friction Surface Treatments (HFSTs) have emerged as one of the most effective and cost-efficient methods for increasing pavement friction and significantly reducing collisions in a variety of traffic conditions around the world. In the last decade, HFST usage has grown across the United States, with most states now using this technology to improve road safety in critical areas. This widespread adoption emphasizes its strategic importance in reducing accidents, particularly on sharp curves, intersections, and steep grades where high levels of pavement friction are required to prevent vehicle skidding and loss of control. HFST not only saves lives, but it also lowers crash rates and costs by significantly improving surface friction [2]. HFST is typically made up of a thin layer of polymer binder and a polish-resistant aggregate, such as Calcined Bauvite (CB), which provides a long-lasting friction surface and reduces skidding [3]. In the United States, HFSTs frequently use epoxy resin binders that meet AASHTO MP41 specifications, which require refractory-grade CB with at least 85% aluminum oxide due to its exceptional hardness and resistance to polishing [4]. This provides long-term friction and accident prevention. However, HFSTs are not without their issues. Early degradation, such as aggregate loss, cracking, debonding, and delamination, can occur as a result of a variety of factors, including pavement quality and epoxy binder. One key difficulty is the poor mechanical connection that occurs when the pavement surface lacks sufficient macrotexture. Improper surface preparation, such as failing to remove dust and debris, can also result in HFST delamination from the pavement surface [5; 6]. Another important consideration is the thermal incompatibility of epoxy and typical pavement materials such as hot-mix asphalt (HMA) or Portland cement concrete (PCC). The coefficient of thermal expansion (CTE) of epoxy-based HFST is significantly higher than that of HMA or PCC, resulting in differential thermal movement between the HFST layer and the underlying pavement. This temperature-induced displacement can cause extra stress on the HFST, resulting in delamination or substrate failure [7]. In response to these concerns, the New Jersey Department of Transportation created a treatment called High Friction Chip Seal (HFCS) to address compatibility issues between the HFST and existing asphalt pavements. This approach uses an asphalt binder instead of a typical epoxy-based HFST, which is more compatible with the pavement substrate [8]. The Missouri Department of Transportation (MoDOT) also performed studies to assess the cost and efficacy of surface treatments created with asphalt-based binders. It was observed that while excellent performance is achieved with epoxy resin under specific aggregates and conditions, modified PG binders, particularly in specific ratios, provide a balanced solution for both friction and cost across various aggregate sizes and types [9]. Recently, state agencies have increasingly prioritized developing asphalt-based alternative binders for HFST applications. Programs like the National Cooperative Highway Research Program (NCHRP) RFP #NCHRP 10-145 underscore the importance of optimizing aggregate selection for HFST. While research has extensively examined HFST performance and explored alternatives to CB, limited attention has been given to developing alternative binders to epoxy resins that are more compatible, cost-effective, and durable [10; 11]. According to recent estimates, the unit costs for HFSTs used by agencies for project planning and estimation range from $20 to $37 per square yard.