Types of Asphalt Concrete Surfacing
摘要
The design and implementation of effective asphalt surfacing solutions play a pivotal role in extending pavement life, optimizing structural performance, and enhancing user safety. This chapter presents a comprehensive exploration of three key asphalt surfacing types—Thinlays, Semi-Rigid Pavements, and Open-Graded Friction Courses (OGFC)—each offering unique attributes tailored to specific performance objectives and site conditions. Thin asphalt overlays, or Thinlays, are introduced as a strategic pavement preservation technique capable of significantly extending fatigue life while maintaining surface geometry and ride quality. The chapter details the design limitations of mechanistic-empirical models for Thinlays, advocating for empirically derived design charts suited to granular pavements with thin bituminous surfacing. Construction guidance emphasizes proper timing, base preparation, material selection, and operational considerations, including temperature management and compaction challenges. Semi-rigid pavements, blending porous asphalt concrete with high-performance polymer-modified cement mortar, are discussed as a hybrid system that combines the flexibility of asphalt with the strength and durability of cement concrete. The chapter outlines their structural advantages, global adoption, material specifications, and step-by-step construction methodology. Through this synthesis, semi-rigid pavements emerge as an optimal solution for high-load environments requiring rapid construction and long service life. Open-Graded Friction Courses (OGFC) are highlighted for their superior surface drainage, noise reduction, and enhanced skid resistance. The chapter explores the unique mix design, aggregate requirements, and performance characteristics that enable OGFC to excel in high-speed, high-traffic settings. Considerations for permeability, maintenance, and environmental suitability are discussed alongside performance testing protocols such as TSR, drain-down, and Cantabro abrasion. By analyzing material properties, construction practices, and application scenarios for each surfacing type, this chapter equips practitioners with a nuanced understanding of surfacing strategies tailored to performance, durability, and cost-efficiency. It provides engineers, contractors, and decision-makers with the knowledge to select and execute the most appropriate surfacing treatments for varied roadway demands.