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RECYCLING AND RECLAMATION OF ASPHALT PAVEMENTS USING IN-PLACE METHODS SUMMARY In-place recycling and reclamation enable agencies to optimize the value of in-place mate- rials 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 neigh- borhood truck traffic. In recent years, petroleum and aggregate economics and supply have increased the need for high-quality, cost-effective alternatives to virgin paving mixtures. Transportation professionals are asking for methods that optimize the value of in-place materials while minimizing traffic congestion and the environmental impact of paving operations. Current in-place recycling processes answer all of these needs. Hot in-place recycling addresses distresses near the surface with the use of one of three hot in-place recycling methods: resurfacing, repaving, and remixing. Distresses in the upper 2 to 4 in. can be minimized using cold in-place recycling. Full-depth reclamation recycles the old asphalt pavement into a stabilized base material that provides good support for the final pavement layers. The current state practices for these in-place recycling methods were assessed using an online survey (45 states responded). In addition to surveying the state agency materials engineers, contractor members of the Asphalt Recycling and Reclaiming Association were asked to answer the same survey questions (34 contractors responded). A comparison of the responses for the two groups of respondents provides insight into topics where there is a good understanding of when, where, and how to use recycling in the most economically and environmentally beneficial applications. The benefits documented in the survey responses of both the agencies and the contrac- tors were that in-place recycling (a) reduces the use of natural resources; (b) eliminates materials generated for disposal; (c) reduces fuel consumption; (d ) reduces greenhouse gas emissions by between 50% and 85%; (e) minimizes lane closure times; ( f ) improves driver safety by improving friction, providing lane widening, and eliminating overlay edge dropoff; (g) maintains height clearances, which eliminates the need to adjust appur- tenances; (h) addresses existing material deficiencies such as moisture damage; (i) reduces costs of preservation, maintenance, and rehabilitation; and ( j) improves base support with a minimum of needed wearing course. There are a number of key factors in achieving these benefits. Success starts with under- standing key project selection criteria such as seasonal weather conditions, roadway geom- etry and features, and the ability of the existing roadway structure to support the recycling equipment. Improved use of technology and alternative combinations of new materials with additives and stabilizers are quickly minimizing historical objections to using in- place recycling on higher traffic volume roadways. Quality control of the construction process is also a key to project success. More than one-third of the contractors responding to the survey indicated that they routinely had a trained quality control technician on site.
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2 Barriers to the increased use of in-place recycling cited by both agencies and contractors were identified as unsuccessful experiences, competing industries, and lack of specifica- tions. Barriers cited more frequently by agencies than contractors were lack of mix designs, lack of agency experience, and lack of experienced contractors. Contractors felt that the lack of project selection criteria was a strong factor limiting the use of in-place recycling.