With the performance limitation of a conventional hot-mix asphalt mixture, the structural integrity of that is highly needed to be enhanced to increase the fatigue life of the mixture. Various geosynthetic alternatives have been widely utilized, such as geogrid, geotextile, or geomembrane layers at the bottom the mixture or on the top of a subgrade to improve the structural integrity of a hot-mix asphalt pavement system. Although reinforcing effects of such interlayers has been reported with some improvements in hot-mix asphalt pavements’ performances, such as mitigating rut or delaying reflective cracks; however, such alternatives do not enhance toughness, tensile strength, or shear strength of the hot-mix asphalt mixture itself due to that the interlayers are usually installed in between two layers in a pavement system and those interlayers do not mix with hot-mix asphalt mixtures. A new plastic fiber-reinforced hot-mix asphalt mixture was proposed in this study to provide more enhanced structural integrity of the mixture not only at the bottom of the mixture but also within the mixture. The developed mixture in this study led to significant enhancements in phenomenological toughness and fatigue life of that at least 1.5 times higher than those for conventional hot-mix asphalt mixtures as resulting from indirect cyclic fatigue tests in loading-control modes and four-point bending beam tests in displacement-control modes.

The increasing demand for sustainable construction materials has driven the exploration of alternative fillers in asphalt production. Traditional asphalt mixtures rely heavily on natural aggregates and petroleum-based binders, contributing to environmental degradation. This study proposes an innovative solution by utilizing Crushed Recycled Marble Stone Powder (CRMSP) as a sustainable filler in SBS polymer-modified asphalt containing high volumes of recycled tire rubber, addressing both resource depletion and waste management concerns. A total of 10 asphalt mixes were formulated with varying CRMSP content (0–100% as a replacement for conventional filler) and SBS polymer (3–5%), and their performance was evaluated through Marshall stability, flow, volumetric properties, and dynamic modulus tests. The results demonstrate that incorporating CRMSP up to 75% significantly enhances asphalt’s mechanical properties. The 75% CRMSP mix showed superior stability (19.2 kN, 24.1% improvement), flow (4.6 mm, 4.5% improvement), and resistance to rutting (lowest rut depth: 0.18 mm, 16.7% reduction) compared to the control mixture. Dynamic modulus testing further confirmed the improved resistance to deformation, with the 75% CRMSP mix exhibiting the highest modulus (6.9 GPa, 15.0% improvement). This research highlights the potential of CRMSP as an innovative and eco-friendly alternative filler, improving asphalt performance while reducing environmental impact. By offering a sustainable way to recycle marble waste and tire rubber, this study paves the way for greener, cost-effective asphalt formulations. Future studies should focus on real-world applications, durability, and long-term performance to validate the potential of CRMSP-modified asphalt in commercial use.

The growing use of reclaimed asphalt pavement (RAP) in warm-mix asphalt (WMA) presents significant challenges when RAP originates from aged polymer-modified binder (PMB) pavements, where severe oxidation and polymer degradation lead to excessive stiffness and poor cracking resistance. This study presents a multi-scale evaluation of a hybrid modification strategy combining recycled engine oil waste (REOW, 3 wt.%) and styrene–butadiene–styrene (SBS, 1–4 wt.%) to restore aged PMB-containing RAP systems under controlled binder conditions. Three binders (control, REOW-modified, and REOW–SBS hybrid) were prepared using a fixed 70/30 virgin-to-RAP binder blend and characterized through rheological analysis, and multiple stress creep recovery (MSCR). The findings show that REOW softened the binder but reduced elastic recovery, whereas SBS modification restored elastic response. Corresponding WMA mixtures with 30 wt.% RAP and 5.0 wt.% total binder content were evaluated for moisture damage, raveling, rutting, and cracking resistance. At the mixture scale, the hybrid system achieved a TSR of 83%, reduced Hamburg rut depth by ~20%, and increased SCB fracture energy by ~30% compared with the control. These findings demonstrate that combined rejuvenation–reinforcement effectively re-mobilizes aged PMB chemistry and restores polymer elasticity, enabling high-performance WMA production with RAP derived from polymer-modified pavements.

With premature deteriorations and performance limitations of hot-mix asphalt (HMA) pavements, innovative solutions are needed to enhance fatigue life or rut-resistance of HMA. Various reinforcing methods are widely utilized such as installing geogrid, geocomposite, or geomembrane layers at the bottom HMA to improve the structural integrity of HMA pavement. Such layered systems sometime improve the field performance of HMA; however, such solutions may not enhance toughness, tensile strength, or shear strength of HMA itself due to the location of interlayer systems. A new mono-strand fiber reinforcing material for HMA is proposed in this study to effectively reinforce the HMA not only at the bottom but also inner-side. Adding a small amount of fiber into HMA leads to significant increases in the phenomenological fatigue life of fiber-reinforced HMA compared to the conventional HMA, and four-point bending beam and indirect tensile tests are performed to observe the effect of fiber reinforcement.

Cambodia’s transportation sector has exhibited tremendous growth in the past decades together with its economic advancement. However, these improvements are only focused on the national and provincial roads, leaving the rural roads underdeveloped. A large percentage of the rural roads in Cambodia are unpaved while those paved roads are in deteriorated condition, making these rural roads prone to structural failure when subjected to heavy truck traffic and massive rainfall. Therefore, an innovative pavement material shall be used in the construction and rehabilitation of Cambodian rural roads. In this study, a composite pavement testbed consisting of a roller compacted cement (RCC) base layer and a modified double bituminous surface treatment (DBST), namely multi-layered bituminous surface treatment (MAST), was constructed in Cambodia and its performance was evaluated. To have a point of comparison, the testbed was divided into three sections with varying combinations of surface and base layer: (1) MAST surface with an RCC base, (2) MAST surface with an aggregate base, and (3) DBST surface with an aggregate base. Initially, a visual inspection was conducted to investigate the surface condition of the testbed. To assess the structural capacity, a light-falling weight deflectometer device was used. Meanwhile, the surface roughness was evaluated through the sand patch test. Lastly, the pass-by test was performed to quantify the noise level of the pavement. Based on the results, the proposed composite pavement performed significantly superior to the typical pavement in Cambodia, which is the third section. In summary, the composite pavement with MAST as the surface layer and RCC as the base layer was observed to be suitable for heavy truck traffic loading and the environmental conditions of Cambodia.

This research takes on a scientific problem originating from the pervasive deterioration observed in the pavements of Bus Rapid Transit (BRT) systems, which presents formidable challenges to their durability and imposes significant financial burdens on BRT organizations. While wear and tear on BRT pavements is a widely recognized concern, there exists a pronounced deficiency in sustainable solutions to address this issue comprehensively. This study endeavored to bridge this scientific gap by exploring the option of incorporating waste plastic aggregate (WPA) and recycled asphalt pavement (RAP) into the pavement material. The series of comprehensive investigations commenced with an assessment of modified binders. We identified a 25% extracted RAP binder as the most suitable candidate. Our research next determined that a 4% WPA content offers optimal results when used as an aggregate replacement in a stone-modified asphalt concrete mix, which is further refined with a 13 mm nominal maximum aggregate size (NMAS) gradation, resulting in superior performance. Under double-load conditions of the Hamburg Wheel Tracking test, rutting in the 10 mm NMAS mixture rapidly increased to 9 mm after 12,400 HWT cycles, while the 13 mm NMAS mixture showed a more gradual ascent to the same critical rutting level after 20,000 HWT cycles (a 61% increase). Real-world application at a designated BRT station area in Seoul reinforced the findings, revealing that the use of 13 mm NMAS with 4% WPA and RAP significantly improved performance, reducing rutting to 75 µm and enhancing pavement resilience. This configuration increased Road Bearing Capacity (RBC) to 5400 MPa at the center zone, showcasing superior load-bearing capability. Conversely, the 10 mm NMAS mixture without RAP and WPA experienced severe rutting (220 µm) and a 76% reduction in RBC to 1300 MPa, indicating diminished pavement durability. In general, this research highlights the need for innovative solutions to address BRT pavement maintenance challenges and offers a novel, environmentally friendly, and high-performance alternative to traditional methods.