The TRB National Cooperative Highway Research Program’s NCHRP Research Report 1007: Evaluation of Bonded Concrete Overlays on Asphalt Pavements documents BCOA practices through a literature review and agency survey; documents performance through site investigations that assessed in-service design, construction, performance, preservation, and rehabilitation; and compares the results of current design methods with actual performance. The lead for the report was Nichols Consulting Engineers, with subcontractors Infrasense, Applied Pavement Technology, Inc., and the University of Illinois at Urbana-Champaign.
BCOA pavements are a fast-growing pavement preservation and rehabilitation treatment
in the United States. They have demonstrated their effectiveness in correcting areas with
excessive rutting and shoving caused by slow, heavy loads, such as at intersections, as well
as for a longer term overlay option on regular mainline pavements. Most BCOA projects
consist of a 3- to 7-in. thick concrete overlay, with or without fibers, with panel sizes ranging
from 4 to 12 ft.
Major advancements have been made recently in design methods for BCOAs. However, there was a need for information on key topics such as optimal BCOA mix design proportioning, construction practices, maintenance, repair, and rehabilitation, as well as a comprehensive review of overall performance. Current assumptions about anticipated design lives of BCOAs are derived from localized studies. Variables impacting design life include the previous condition of the existing pavement structure, the time-dependent degree of bond between layers, overlay thickness, panel size, construction practices, environment, and traffic. Typical BCOA design lives are uncertain, and the timing and types of maintenance and repair activities need further study and definition.
Some highway agencies are reluctant to use BCOAs because of a lack of experience and
information. Thus, research was needed to determine expected BCOA performance. Other
aspects of BCOAs such as construction practices (“do’s and don’ts”) and maintenance,
repair, and rehabilitation requirements and procedures also need attention.
Under NCHRP Project 01-61, “Evaluation of Bonded Concrete Overlays on Asphalt
Pavements,” Nichols Consulting Engineers was asked to (1) investigate factors that may
impact BCOA performance including design procedures, specifications, mix design proportioning, construction practices, and maintenance and repair techniques; (2) document
in-service BCOA performance through a literature review and survey; (3) conduct field
surveys of selected BCOA projects; (4) develop representative performance prediction
curves suitable for use in BCOA design selection based on the documented performance
of a range of BCOA projects; and (5) compare actual versus predicted BCOA performance
using current design procedures.
Contributor(s): National Academies of Sciences, Engineering, and Medicine; Transportation Research Board; National Cooperative Highway Research Program; Linda M. Pierce; Sarah E. Stolte; Nick Weitzel; Jose Medina; Tom Van Dam; Kevin Senn; Jeff Roesler; Gail M. Scott; Sushobhan Sen; Omar A. Jadallah; Ken Maser; Adam Carmichael; Kelly Smith; Kurt Smith
The report can be downloaded from here.