Interstate 44, constructed in 1976, connects three of Oklahoma's largest cities and is a primary corridor to the Midwest. By 2004, the Oklahoma City section was in desperate need of repair. In some areas, severely damaged sections of concrete were removed completely and repoured.
Concrete pavement restoration allows lanes to remain open while repairs take place.
A 2003 physical survey of the Oklahoma City section of Interstate 44 proved to the Oklahoma DOT (ODOT) that the road was in desperate need of repair. Cracks and potholes created a bumpy, uneven surface for drivers. Their solution: concrete pavement restoration (CPR).
The agency discovered that the section of I-44 between I-40 and I-35 suffered from severe panel damage and faulted pavement. Its survey 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. Pavement replacement areas were quantified using a vehicle-mounted digital image collection system.
Due to the road's high level of traffic — between 125,000 and 135,000 vehicles daily — the agency needed a fast and long-lasting solution that was as unobtrusive as possible. Rather than remove and replace entire sections of pavement, which would cause major delays and lane closures, managers chose a cost-effective method that addresses the root causes of pavement distress: CPR, which consists of using one or more of the following techniques:Full-depth repair: for cracked slabs and joint deteriorationPartial-depth repair: for joint and crack slab deteriorationCross-stitching: to repair low- and medium-severity longitudinal cracksDiamond grinding: to extend serviceability, improve ride and skid resistance, and reduce noiseDowel-bar retrofit: to restore load transfer at joints and cracksGrooving: provides traction, thus reducing wet-weather accidents and preventing hydroplaningJoint and crack sealing: minimizes infiltration of water and incompressible material into the joint systemRetrofitting edge drains: for adding a longitudinal drainage systemRetrofitting concrete shoulder: to decrease pavement edge stresses and corner deflections.Slab stabilization: to fill small voids underneath the concrete slab.
The agency contracted with Penhall Co. of Anaheim, Calif., to begin work in 2004. The project included lane repairs in both directions, as well as auxiliary and ramp lane repairs. Crews used several CPR techniques, depending on an area's level of damage. Severely damaged panels were removed and replaced with new concrete, but many existing portions were simply rehabilitated.
To restore structural support to existing concrete, voids that had formed under slabs at joints, cracks, and edges were filled. Dowel bar retrofit — which involves 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 provided a smooth, quiet, and skid-resistant driving surface.
Because repairs were applied only to areas that specifically needed them, traffic disruption was kept to a minimum during this five-phase project. To keep the freeway open as much as possible, most of the work was conducted at night. Plus, “user costs are minimized by performing the work during nighttime hours,” says ODOT Resident Engineer Tom Hubbard, PE.
Working around the temporary nighttime lane closures created some additional challenges, however, especially when new concrete needed to be placed. Careful scheduling was needed to complete the necessary repairs in a timely manner to accommodate the temporary 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, which meant 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 in July 2009. “The cost-effective nature and minimized user costs are key in the success of pavement restoration,” says Hubbard of the $11.3 million project, which was funded by 80% federal funds and 20% state funds. The agency expects the repairs to extend the service life of the concrete another 15 years.
— Cline was the 2009 summer editorial intern for PUBLIC WORKS' sister magazine CONCRETE CONSTRUCTION.