By: Tom Miller; Contributing Author
RGG United Contractor Inc. (RGG) completed a major terminal gate repaving project at Phoenix Sky Harbor International Airport three months ahead of schedule, using reversible metal paving forms that were designed to accommodate different concrete depths.
The project was part of a $15.4 million contract to repave areas where Southwest Airlines aircraft taxi to and from the gates at Terminal 4, the airport’s busiest terminal. At the time of the award, FAA Administrator Michael Huerta highlighted the importance of the project by pointing out that deteriorating pavement can produce debris that damages aircraft and engines.
The contract included removal and replacement of approximately 94,000 sq yd of 18-in. to 22.5-in. concrete pavement, totaling 51,500 cu yd of concrete. According to Civil Engineer and Operations Manager John Kliethermes, of RGG, the job was finished three months ahead of schedule, despite severe rain and flooding in the Phoenix area.
Flexibility in forms
For the project, RGG selected steel paving forms. At the outset, Kliethermes cautioned the manufacturer that the forms had better be straight, as forms purchased earlier from another source proved to be under-designed and failed the requirements for rigidity and straightness in the field. He was pleased with the quality and accuracy of the new forms, saying, “We insisted that the forms be held within a 1⁄16-in. tolerance, and they were.”
The contractor ordered 160 paving forms in two different sizes, totaling more than 1,600 linear ft. All are 10 ft in length, made of 1⁄4-in. steel, and designed so they can be used for two different pavement depths. Some of the forms can be used for either 18-in. or 22.5-in. pavement, while others can be used for either 18 in. or 16 in. depths. This cost-effective feature provided greater flexibility for use on this and future jobs.
Prior to the concrete work, the original pavement was removed by Banicki Construction of Tempe, Ariz., under a joint venture with RGG. The concrete was broken with an excavator-mounted hydraulic impact breaker. The resulting material then was crushed to provide a base for the new pavement. Kliethermes said the original base was old fill material that did not meet current FAA specifications. The crushed concrete met FAA Standard P-219 for Recycled Concrete Aggregate Base Course. By recycling the old pavement, the environmental impact of the project also was reduced substantially.
Kliethermes said that a majority of the concrete on this job was 18 in. thick, with sections thickened to 22.5 in. where load transfer dowels were not used. He explained that the Southwest Airlines fleet is composed entirely of Boeing 737 models, which constitute Group 5 design and require a pavement thickness of 18 in.
The concrete mix was designed to lower the potential for alkali-silica reactivity (ASR) while still achieving 650-psi flexural strength. Kliethermes reported that the concrete contained 30% fly ash due to the highest potentially reactive aggregates in the nation being from the Salt River near Phoenix. He said most other sites are closer to 10-15% fly ash by comparison.
The forms all incorporate angled stake pockets that allowed them to be staked in either direction. Gusset-style end connections facilitated bolting the forms together securely. Although the forms were made with a 2-in. top tread to allow a paver to ride along the top if desired, the paver used on this project was equipped with rubber-tired wheels that straddle the forms, as well as a wire guide system and an internal concrete vibration system.
