Concrete Overlay on Asphalt Pilot Project at Woodland SR 113: Construction

This report documents the design and construction of a concrete overlay on asphalt (COA) pavement on State Route 113 in Woodland, California, one of the first COA projects in the Caltrans road network. The project site extended over approximately 4 mi. of a two-lane secondary road. The concrete slabs were a half-lane wide (6×6 ft.) and 6 in. thick. The transverse joints were undoweled, but tie bars were installed at all the longitudinal joints. The outside slabs were 2 ft. wider than the interior slabs to provide a concrete shoulder. The project included a section with newly placed, rubberized, gap-graded asphalt mix base. A rapid-strength concrete mixture with Type II/V portland cement designed to be opened to traffic in 24 hours was used for construction of the overlay. The northern part of the project (PM 14.760 to PM 17.580) was built in October and November 2018, while the southern part (PM 11.860 to PM 12.890) was built in April and May 2019. The concrete mixture was produced in a fixed plant and transported in ready-mix trucks 25 mi. to the construction site. A slipform paver was used to consolidate and finish the concrete. A number of the quality control/quality assurance (QC/QA) tests and evaluations summarized in this report were conducted before, during, and after the construction of the concrete overlay. These QC/QA tests and evaluations revealed no major design or construction issues with the concrete overlay, but they did show that the condition of the asphalt base was very poor, particularly in the northern part of the project.