Construction, Instrumentation, and Performance of a Double Sized Slab Designed for Airport Runways

Based upon the past performance of airfield portland cement concrete slabs, the FAA has provided guidance for runways slabs sizes. The guidance recommends for a runway of 150 ft wide, the standard size slabs should be 18.75 ft wide by 18.75 ft or 20 ft long. A test slab was placed and instrumented at double the standard size of 37.5 ft by 37.5 ft. Had the slab been constructed with normal portland cement concrete it would have surely tried to crack into quarters. The test slab was constructed rapidly using a calcium sulfoaluminate cement which has less than 1/3 the shrinkage of portland cement concrete and no cracking has been observed after 1 year. This paper discusses the construction and instrumentation of the test slab. The concrete portion of the test pavement was placed in 47 min using volumetric mixing trucks. The rapid setting properties of the belitic calcium sulfoaluminate (belitic CSA) cement was intentionally retarded to allow for achieving a 400-psi flexural strength in 4 h rather than 550 psi in 1 h if not retarded. Vibrating wire strain gauges were installed prior to placing the concrete layer. Survey markers were installed on the slab in nine locations and elevations were surveyed periodically for 1 year. This paper also discusses the advantages that would be achieved using this high strength, very low shrinkage, and high longevity cement with double the slab size. This belitic CSA concrete pavement would likely have a 75 year or more pavement life, with less joints, less distress due to load and non-load related deterioration, and low maintenance.