A survey of the Oklahoma City section of I-44 proved to the Oklahoma Department of Transportation (ODOT) that it was in desperate need of repair. Their solution: concrete pavement restoration (CPR).
The CPR method allowed lanes to remain open while repairs took place.
ODOT discovered the section of I-44 between I-40 and I-35 suffered from severe panel damage and faulted pavement. The survey results revealed transverse joint faulting from ¼ to 3/8 inch with isolated ½- to 5/8-inch faults, and longitudinal joint faulting from ¼ to ¾ inch.
Due to the road's high level of traffic—between 125,000 and 135,000 vehicles travel on it every day—ODOT needed a solution that was fast and long lasting, with as little traffic disruption as possible. Rather than beginning a costly remove-and-replace project, ODOT chose CPR as a cost-effective method that extends concrete's life.
Lane repairs in both directions, as well as auxiliary and ramp lanes, began in 2004, with CPR used on all parts of the project. The method involved several elements, depending on an area's level of damage. Severely damaged panels were removed and replaced with new concrete, but many existing portions were rehabilitated with repairs.
To restore structural support to existing concrete, voids that had formed under slabs at joints, cracks, and edges were filled. Dowel bar retrofit (DBR)—which involved cutting and cleaning slots across joints or cracks, placing dowel bars, then backfilling the slots with cement—linked slabs together to evenly distribute the load. All joints were sealed to limit water or corrosive chemicals from entering and damaging concrete and dowel bars. Finally, diamond grinding was used on the concrete surfaces to provide a smooth, quiet, and skid-resistant driving surface.
Because CPR repairs are applied only to areas that specifically need them, traffic disruption was kept to a minimum during the five-phase project. To save additional costs and keep the freeway open as much as possible, most of the work was conducted at night. “In the past decade, many dowel bar retrofit and diamond grinding projects have been completed in the Oklahoma City metro area,” says Tom Hubbard, PE, the resident engineer for ODOT. “In each case, user costs were minimized by performing the work during nighttime hours.”
Working around the temporary nighttime lane closures created some additional challenges, however, especially when new concrete needed to be placed. Careful planning was used to complete the necessary steps while accommodating the temporary nighttime closures. Safety of both workers and travelers was another major concern. During the last phase of the project, two of the four lanes remained open, and fast, heavy traffic continued during construction. Activity briefings each evening helped keep safety a priority on the jobsite.
Despite the challenges and dangers, the renovations were completed this summer. “The cost-effective nature and minimized user costs are key in the success of pavement restoration,” says Hubbard of the $11.3 million project. ODOT expects the CPR repairs to extend the service life of the concrete another 15 years.