Case Study of Low-Volume Concrete and Thin Unbonded Concrete Overlay Pavements in Michigan

Abstract: In the state of Michigan, demonstration projects are constructed to generate performance curves and determine the feasibility of adopting the construction method used in such projects as standard practice by the Michigan Department of Transportation (MDOT). Typically, most low-volume roads are constructed with Hot Mix Asphalt (HMA) due to cheaper construction costs and repair options. Comparably, a standard low-volume Portland cement concrete (PCC) pavement design in this state has a slab thickness of 8 inches. In an attempt to assess the feasibility of constructing a concrete pavement that has a comparable cost and performance with HMA for low-volume roads, the Michigan Department of Transportation (MDOT) constructed 6-inch-thick jointed plain concrete pavement demonstration projects on M-13 in 2005 and M-99 in 2006. These pavement sections have no load transfer devices and a shorter spacing of joints to reduce construction costs while accommodating reduced curling stresses on the thinner slabs. In another demonstration project, a 4-inch unbounded concrete overlay with a reduced longitudinal joint spacing of 5.5 feet for M-3(2005) and 5 feet for M-1(2010) were constructed without dowel or tie bars. A regular MDOT unbonded concrete overlay is 6-inch or thicker and has 12 feet joint spacing with dowel and tie bars.

Continuous monitoring of the project has been conducted since construction. Visual surveys, non-destructive testing, cost, and pavement performance data have also been collected. This paper focuses on analyzing construction and pavement condition data collected throughout the service life of these pavement sections to determine if low-volume concrete pavement and thin unbonded concrete overlay can provide adequate performance and be accepted as a standard reconstruction method in Michigan. After about 13-18 years of service life, methods have been found to provide acceptable performance. Recommendations have also been made regarding the best construction and maintenance practices required to ensure the long-term performance of the pavement.