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3 CHAPTER ONE INTRODUCTION BACKGROUND In recent years, petroleum and aggregate economics and sup- ply have increased the need for high-quality, cost-effective alternatives to virgin paving mixtures. Transportation pro- fessionals are asking for methods that optimize the value of in-place materials while minimizing traffic congestion and the environmental impact of paving operations. In-place recy- cling and reclamation enable agencies to optimize the value of in-place materials and minimize construction time and traffic flow disruptions, as well as to reduce vehicle emissions from long traffic queues. In-place recycling and reclamation also reduce the number of construction vehicles moving in and out of the construction area and neighborhood truck traffic. FIGURE 1 Pavement condition and type of in-place recycling method (Faster 2007). Current pavement recycling and reclamation methods answer all of these needs, particularly the following: A number of benefits can be realized with the use of in- Hot in-place recycling (HIR) place recycling processes. These options provide economical Resurfacing and sustainable solutions that reduce demand on raw mate- Repaving rials, energy consumption, and production of greenhouse Remixing gases, while maintaining functionality and performance. Cold in-place recycling (CIR) Advantages include the following: Full-depth reclamation (FDR) Construction benefits Different methods of recycling are applicable to different Minimizes traffic disruptions types, levels, and severity, and hence different periods in the Shortens lane closure times pavement life (Figure 1). Typically, HIR is used when the Maintains height clearances majority of the pavement distresses are minimal and limited Pavement condition improvements to the upper few inches of the surface of the roadway with no Improves friction evidence of structural problems (i.e., longitudinal cracking Minimizes edge dropoff concerns in wheel path, alligator cracking, and edge cracking). CIR Reduces surface irregularities and distress type, is used when there is a higher number, type, and severity severity, and extent of non-load-related distresses that may extend farther down Addresses some existing material problems such as from the surface. CIR with an overlay can be used to address moisture damage some load-related distresses. FDR is an in-place rehabilita- Environmental benefits tion process that can be used for reconstruction, lane widen- Conserves nonrenewable resources ing, minor profile improvements, and increased structural Reduces emissions capacity by addressing the full range of pavement distresses. Reduces fuel consumption Reduces number of haul trucks The anticipated depths of the distresses, combined with Eliminates materials generated for disposal the overall existing asphalt pavement thickness, are used to Cost benefit identify the type of in-place recycling process(es) that can be Provides economical methods for pavement preser- expected to extend the life of the pavement most economically. vation and maintenance