EFFECT OF RECYCLING AGENTS ON THE STRUCTURAL PERFORMANCE OF RECYCLED ASPHALT CONCRETE MATERIALS

In recent years, reuse/recycling of existing pavement materials has emerged as a good rehabilitation and maintenance alternative as it offers several benefits over the use of conventional paving materials and techniques. The majority of the research and development programs associated with recycling have concentrated on equipment development, construction techniques and sequences, mix design, pavement performance, and cost and energy concerns. Little information is available from the literature defining properties of recycled mixtures for use in pavement design. The main aim of this research was to evaluate certain structural materials characteristics of recycled asphalt concrete mixtures employing recycling agents. The mixtures tested were designed by means of a laboratory mix design procedure predicated on adding the proper amount of recycling agent to the old asphalt to restore selected physical properties of the asphalt cement. The quantity of recycling agent ultimately used was based on selected mixture and binder properties. This procedure is explained more fully in this paper. A secondary goal was to evaluate the effects of 2 widely different recycling agents and the effects of 2 different sources of salvaged material. A lab standard mixture of AC-10 and crushed limestone was tested in the same sequence as the recycled mixtures and was used as a control test mixture. The balance of the paper describes the materials, recycling agents mixture design procedure, and test results in detail.