Almost two decades ago, the U.S. Army Engineer Research and Development Center tested 10 rapid-setting concrete compounds – polymeric patching material, magnesium phosphate-based and high alumina cements, and specialized proprietary blends – to identify the best option for quickly repairing military runways.
The repair material had to achieve 3000 psi compressive strength in 3 hours at 90 degrees F, 500 psi bond strength to portland cement within one day of curing, and 1000 psi bond strength to other rapid-setting materials. It also had to be easy to use: a bagged product placed with traditional equipment and tools.
Concrete made with Rapid Set® calcium sulfoaluminate (CSA) cement met all these criteria. Rapid Set® is a lower-carbon alternative to ASTM C150 portland cement and ASTM C595 Type 1L portland limestone cement for concrete construction and repair. It is mixed, placed, and finished using the same tools and equipment and reaches structural strength in 1 hour without accelerators.
Rapid Set® is more durable than portland cement. It shrinks much less while curing, minimizing entry points for water and chlorides; isn’t susceptible to sulfate attack; and is less prone to alkali-silica reaction (ASR) in the presence of reactive aggregate. (Learn more about the material and earn CE / PDH credits here.)
For these reasons, civilian airports as well as military airbases use Rapid Set®-based products to patch runways and taxiways, install lighting, and build electric and mechanical equipment pads.
A Fast Fill Project
Filling old trenches at a U.S. Air Force isn’t as stressful as filling a crater blasted into a runway during war, but the requirements are virtually the same: very early strength for fast return to service.
When James Fletcher Construction’s crews arrived at Randolph Air Force Base about 15 miles outside San Antonio, they were expected to complete the job quickly. Two trenches in the concrete pavement of the airbase’s fueling station had to be filled with a material strong enough to sustain heavy fuel tanker traffic within hours of placement.
They used Rapid Set® Concrete Mix, a multipurpose blend of Rapid Set® cement, quality aggregates, and an air-entraining admixture for freeze-thaw durability. To that they added:
The crew blended these components with water in a CS Unitech Hippo portable mixing station. After pressure-washing the surface, they poured the material into the trench, filling and smoothing the placement with hand trowels before water-curing the finished placement for at least 1 hour.
