Ultrathin Wearing Course for Pavement Preventive Maintenance: A State-of-the-Art Review

Ultrathin wearing course, as a flexible and high-performance preventive maintenance technology, has gained widespread application due to its cost-effectiveness, environmental benefits, and enhanced durability. To further promote the application of ultrathin wearing courses in practice, this paper attempted to evaluate them from the perspectives of materials, performance and functions, construction processes, cost-effectiveness, and environmental impact. Ultrathin wearing courses significantly improved pavement performance in terms of crack resistance, skid resistance, noise reduction, and snow-melting capabilities through the integration of high-viscosity modified asphalt and optimized aggregate gradation, thereby reducing maintenance frequency. While ultrathin wearing courses might generate higher greenhouse gas emissions compared to other preventive maintenance methods, such as microsurfacing or chip seals, its extended service life and capacity to incorporate recycled materials position it as a competitive solution. Looking ahead, the development of ultrathin wearing courses will focus on three key dimensions: material performance enhancement, construction technology improvement, and lifecycle cost optimization. The incorporation of innovative additives such as nanomaterials and polymers, along with intelligent construction techniques such as automated compaction control, will drive future advancements. Ultrathin wearing courses also offered potential for enhanced urban heat island mitigation, noise reduction, and environmental resilience, further expanding its application. As such, ultrathin wearing course could stand as a versatile and effective maintenance technology poised to address the growing demands of modern infrastructure.