Mary Stroup-Gardiner

Recycling and Reclamation of Asphalt Pavements Using In-Place Methods

In-place recycling and reclamation of asphalt pavements provides agencies with the ability to optimize the value of in-place materials, minimize construction time and traffic flow disruptions, and reduce the number of construction vehicles moving in and out of the construction area. This report discusses the use of hot in-place recycling, cold in-place recycling, and full-depth reclamation. Information for this report was gathered by literature review, a survey of state departments of transportation and contractors, and selected interviews.

Recycled Materials and Byproducts in Highway Applications--Summary Report, Volume 1

Recycled materials and industrial byproducts are being used in transportation applications with increasing frequency. There is a growing body of experience showing that these materials work well in highway applications. This study gathers the experiences of transportation agencies in determining the relevant properties of recycled materials and industrial byproducts and the beneficial use for highway applications. Information for this study was acquired through a literature review, and surveys and interviews with state department of transportation staff. The report will serve as a guide to states revising the provisions of their materials and specifications to incorporate the use of recycled materials and industrial byproducts, and should, thereby, assist producers and users in leveling the playing field for a wide range of dissimilar materials. The entire report is presented in eight volumes. The first, this summary report, is available through hard copy and on the Internet. The next seven volumes will be available through the Internet only.

Use of Reclaimed Asphalt Pavement and Recycled Asphalt Shingles in Asphalt Mixtures

This synthesis summarizes current practices for the use of reclaimed asphalt pavement (RAP) and recycled asphalt shingles (RAS) in the design, production, and construction of asphalt mixtures. It focuses on collecting information about the use, rather than just what is allowed, of high RAP, RAS, and/or a combination of RAP and RAS. A literature review and a survey of state agencies were used to document current knowledge and practices. Case examples were developed for five key topics. The first example shows how the Georgia Department of Transportation (DOT) developed and revised its specifications to encourage contractors to consistently submit mix designs using from 30% to 40% RAP in all pavement layers. The second example documents contractor practices and procedures used to produce and place high RAP mixtures for Georgia and five other surrounding states (Alabama, Florida, North Carolina, South Carolina, and Tennessee). The third case example provides guidance from a Missouri contractor for processing RAS for use in asphalt mixtures. The fourth case example shows how the Minnesota DOT collected performance data from nonstate agency project roadway databases (i.e., county roadways) used in surface mixtures. The fifth example documents four recent research projects (three RAP, one RAS) designed to estimate the percentage of recycled asphalt binder that can be transferred to the virgin aggregate in the asphalt plant before the virgin asphalt is added (i.e., dry mixing).

Methods and Practices on Reduction and Elimination of Asphalt Mix Segregation

The report documents methods and practices on reduction and elimination of asphalt mix segregation. This synthesis provides guidance on how to reduce or eliminate segregation during aggregate production, mix design, asphalt mix production, mix transport and transfer, and placement. Successful options for reducing or eliminating segregate, as well as caveats for what not to do, are included for the following topics: segregation descriptions and segregation specifications (standard sections, advantages, disadvantages, incentives/disincentives, and desired changes). The findings are based on a survey was sent to members of the American Association of State Highway and Transportation Officials (AASHTO) Committee on Construction. The same on-line survey was submitted to state Asphalt Pavement Association (APA) representatives to collect information from the paving industry’s perspective on successful construction equipment and practices for minimizing or eliminating segregation, as well.