The deplorable conditions that have developed in our highway system is one of the major problems confronting transportation agencies today. Rapidly escalating maintenance and reconstruction costs, coupled with a nearly fixed level of highway funding have contributed significantly to this problem. Asphalt pavement recycling is a viable rehabilitation method that can be used to help solve this serious problem; for recycling can be an economical, as well as an energy efficient rehabilitation alternative. The purpose of this study is to fully investigate asphalt pavement recycling.; Asphalt pavement recycling can be classified into three major areas: surface recycling; central plant recycling; and in-place recycling. This study investigates the type of equipment used, the construction methods employed, as well as the various considerations and limitations associated with each recycling method. Previous recycling jobs were analyzed to determine rates of production, unit costs, unit rates of energy consumption and specific problems encountered during recycling operations.; A set of guidelines was developed to assist the pavement engineer in determining if an asphalt pavement is a suitable candidate for recycling. The recycling guidelines provide a formal method for evaluating the existing pavement structure, identifying its rehabilitation needs, determining the probable cause of distress or failure, as well as identifying an appropriate recycling method. The recycling guidelines also comment on the design of the recycled mixture and the design of the recycled pavement.; A set of construction guidelines was developed to assist the construction engineer in implementing the recycling method identified by the recycling guidelines. The guidelines provide assistance in formulating and evaluating a specific recycling system. Project management decisions, recycling process variability and potential problem areas associated with the proposed recycling system were identified. Guide specifications were synthesized for the major forms of asphalt pavement recycling so that existing specifications can be modified or supplemented for recycling use.; A section of an Indiana highway was selected to demonstrate the use of the recycling guidelines. The existing pavement structure was fully characterized and a recycling rehabilitation method, including six design and pavement design, was selected and formulated using the procedures developed in this study.
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