Abstracts
Performance and Design of Whitetopping Overlays fo
By Rasmussen, Robert
Transtec, Inc.
1012 East 38 1/2 Street
Austin, TX 78751
PH: 512-451-6233
FAX: 512-451-6234
E-Mail: robotto@transtecinc.com
Problem Statement
Whitetopping, concrete overlays of asphalt pavements, has been used extensively throughout the United States. Essentially, there are 3 types of whitetoppings Conventional, Thin, and Ultra-thin. Conventional whitetopping is typically greater than 8 inches thick. The design of these overlays has been based on conventional procedures, which assumes the existing asphalt pavement is a stabilized base course. Ultra-thin whitetopping is a more recent class of whitetopping. They are typically between 2 and 4 inches thick and have been applied to intersections, ramps, etc. where the asphalt pavement has not performed adequately. Thin whitetopping overlays are between 4 and 8 inches thick. They have typically been used on low volume primary and secondary roads and are usually designed using conventional whitetopping design procedures. Research has found that bonding or interaction between the existing pavement and the overlay, and short joint spacing contribute significantly to the overlay performance. This is not properly accounted for in current design practices. In many instances, all three of these overlay procedures have exceeded their design expectations. Research is needed to determine the appropriate design procedures for all classes of whitetoppings (i.e., are the design concepts and construction techniques of Ultra-thin whitetopping applicable to thicker overlays?). In addition to the design procedure, research is needed to identify the existing pavement conditions that influence whitetopping performance for each class of overlay.
Research Objectives
1. To document, based in part on available data, the performance of the three classes of whitetopping overlays subjected to heavy loads. 2. To develop a whitetopping design procedure for each class of overlay that takes into account critical parameters and site conditions. 3. Develop best practices construction and quality control guidelines for each class of whitetopping that address the issues needed to ensure that quality pavement is built. 4. Identify potential rehabilitation alternatives for each class of whitetopping. These alternatives will consider best practices, sensitivity to environmental conditions, design parameters, quality control and related specifications, possible problems that may be encountered, and the most probable solutions to those problems.
Research Method
The basic premise of the research plan is that the design, analysis, construction, and rehabilitation of whitetopping overlays should be combined using the Systems Approach. This approach for whitetopping design will allow the optimization of a pavement type, thickness, and rehabilitation strategy based on all factors that affect the performance and economic feasibility of the structure. Conventional methods of analyzing and designing pavement structures cannot, simply and rationally, draw any conclusions when comparing factors such as materials characteristics, safety, mix design parameters and user costs. However, the Systems Approach provides a method of comparing the effects that each of these factors have on performance, user costs, agency costs, and environmental conditions.
Product
1. A CD-ROM which contains the Systems Analysis Whitetopping Design application. 2. A database providing easy access to literature, performance data, and other whitetopping design procedures. 3. A five-volume final report including: · A summary report, · A thorough description of the design procedure, · A set of construction guidelines, · Probable whitetopping rehabilitation alternatives, and · Appendices with supporting data.
4. A CD-ROM and/or web-page containing a multimedia interactive presentation.
Completion Date: Nov 01, 2001
Category: Structural Design
Keywords: Rehabilitation, TWT, UTW, Whitetopping,
Date Posted: Aug 10, 2000
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