Candidate for fully permeable shoulder retrofit validation site
Construction of BCOA Sections at the UPCRC ATIRC Facility.
Between February 23 and 25, the Concrete Pavement Industry constructed fifteen
Bonded Concrete Overlay of Asphalt Pavements (BCOA) sections at the UCPRC’s
Davis testing facility. The results obtained by testing on these “thin BCOA” sections
will serve as the basis for recommendations and guidance on the technology’s
use as a rehabilitation alternative in California, as directed by Caltrans/UCPRC Element 4.58B.
This set of sections includes a variety BCOA solutions, including several
concrete mixes (type II/V, type III, and calcium sulfoaluminate
cements), slab thicknesses (4.5 and 6 in.), slab
dimensions (6x6 sq. ft, 6x6 sq. ft. with widened lane, and 12x12 sq. ft), asphalt
base types (conventional hot mix asphalt and rubberized asphalt), asphalt
base thicknesses (2 to 5 in.), asphalt conditions (old and new), and
surface preparation techniques (sweeping, micromilling, and milling). All the
sections were built with high early strength mixes designed to provide 400 psi flexural
strength in either 4 or 10 hours, time constraints required for the short construction
windows imposed by high traffic volumes and user demand on most of the main
roads in the Caltrans network.
A total of 560 sensors embedded in the sections will measure displacement, strain,
temperature, moisture, and relative humidity. The instruments collecting data on
the concrete-asphalt interface have received especial consideration since this
area’s behavior is regarded as one of the main factors determining how this
rehabilitation technique will perform. Among the sensors, 245 have already been
monitoring the effects of temperature and moisture-related shrinkage since
construction; the rest will monitor the dynamic response of the sections
under heavy vehicle simulator (HVS) loads once the one-year-long accelerated
test period begins in May 2016. Laboratory testing, which is focused on the
mechanical characterization of asphalt, concrete, and the interface between
this two, has already started.
Expected outcomes from this research project are optimized concrete and
rubberized asphalt mix designs for use as overlays and bases, respectively, for
BCOA rehabilitations in California. An improved understanding of BCOA
mechanics and performance is also expected from the project, which
will end in September 2017.
To date, a large number of institutions have been involved in
this research. These include the University of Pittsburgh, which is
providing technical leadership and support, and the Southwest Concrete Pavement
Association, which is coordinating Industry support that included
the construction of the BCOA sections.
Important Note for Caltrans Users: Prior
to scheduling pavement preservation (preventive maintenance or CAPM) or roadway
rehabilitation work on flexible pavement highway sections, the District Materials
Engineer and/or the Project Manager should review
this spreadsheet to
ensure that the proposed project does not include sections active in
the “Quieter Pavement Research” (QPR) testing program. If the proposed
project is within a QPR test section, please
contact Linus Motumah of the
Caltrans Office of Pavement Design before scheduling the work.
To view maps that show where the sections are located, click the following
(or copy-and-paste it into a new browser window for a slightly larger view).
For more information,
contact John Harvey of the UCPRC or