The Concrete Paving Association of Minnesota (CPAM) reported that Olmsted County, Rochester, Minnesota, USA, constructed an unbounded concrete overlay construction featuring fabric interlayer as a replacement for a hot mix asphalt interlayer. The unbounded overlay was of the CSAH 25—from CSAH 3 to CSAH 22W (W Circle Dr)—Salem Corners, 8.6 kilometers (5.345 miles), for $3.7M (Project S.P. 055-625-023).
In 1982, the following was constructed:
- a 17.8-cm (7-in) unreinforced concrete pavement
- 5 cm (2 in) of Class 5 aggregate base
- 3.8 cm (1.5 in) of road mix bituminous surface, and
- 7.6 cm (3 in) of Class 2 aggregate base
In the year 2000, the 1982 pavement was retrofitted with dowel bars in the outside wheel paths. Over time, the joints deteriorated due to the absorptive properties of the aggregates used in the original pavement. However, outside the deteriorated areas, the dowels and original concrete continue to provide the desirable load transfer qualities.
Thus, in 2015, the unbonded overlay option was selected to provide the county another 30-plus years of service. CPAM took some exciting photos of the
construction, including the installation of the Geotex® paving fabric manufactured by PropexTM and the 3MTM HoldFast 70 Spray Adhesive. The adhesive is used to stick the fabric to itself and the concrete subbase. The adhesive is used as a replacement for the traditional collated pins and galvanized discs.
The fabric interlayer has been on the market for some time as a replacement for a hot-mix asphalt interlayer. The hot-mix asphalt interlayer can be costly as it requires its own paving operation. The fabric interlayer provides separation from the existing road surface to prevent old joints and cracks from reflecting through to the new overlay surface. The fabric is day-lighted to the edges of the pavement to allow for a drainage path for rain water and moisture infiltrating from the surface.
For a copy of the abstract for this project on Olmsted County’s eGram site, please click here.
For an overlay and for help with any concrete questions or resources, please contact the CPAM office: http://www.concreteisbetter.com.
Greg Bauer, PE, CPAM Pavement Promoter | Telephone: 651-762-0402. | Fax: 651-762-0638
