Drying Behavior of a Quadruple-Sized Belitic Calcium Sulfoaluminate Airfield Concrete Slab

There would be significant benefits in construction, maintenance, and service life of airfield pavement if concrete slabs were constructed overnight and in sizes of 40 ft or more, while being capable of handling wide-body aircraft. We investigated using belitic calcium sulfoaluminate (BCSA) cement concrete instead of portland cement concrete for this purpose. Seattle Tacoma International Airport (SEA) has a 25-year successful history of using BCSA for rapid airfield construction. A test slab of 11.3 m × 12.2 m × 0.5 m (37.5 ft × 40 ft × 18 in.) thick was placed at SEA on November 1, 2019. This report describes the placement, instrumentation, and an analysis of slab behavior in terms of shrinkage and curling, as measured using embedded strain gauges. Preliminary data show exceptionally low strains even for such a large slab. This unusual behavior is probably due to the unique chemistry of BCSA, which involves early strength gain caused by water-retaining ettringite, followed by the minimal shrinkage associated with belite content. Analysis of the data collected over a year shows that this unique chemistry would support improving construction protocols and slab design allowing overnight replacement of four contiguous, regular-sized portland cement concrete slabs with a single BCSA slab on an active taxiway.