Hot In-Place Recycling of Asphalt Pavements: Oregon Experience

Abstract

A study was carried out to evaluate the potential of using hot in-place recycling (HIR) as a rehabilitation alternative in Oregon. Data from six Oregon Department of Transportation HIR projects constructed in 1992-1993 were analyzed. The construction equipment, pavement properties, project selection, mix design, and resulting performance are summarized and presented. Only one HIR project was successful in rejuvenating the pavement and restoring ride quality. Of particular interest are the problems encountered in the other projects, which are discussed and show the importance of preliminary engineering and project selection for successful HIR. The lessons learned from the six projects are used as guidelines for selecting suitable candidate pavements for HIR. The results from the HIR projects combined with a literature review and limited laboratory testing led to a recommended HIR mix design procedure. Significant findings include the following: (a) HIR is a developing technology that shows promise for properly selected projects, (b) project selection is the most critical step in the HIR process, and (c) critical mix design inputs come from testing in situ pavement properties and laboratory specimens remolded with rejuvenating agent added.