Workers from two 12-hour shifts slipformed three 172-foot high reinforced concrete storage silos in 10 days in Baltimore, Maryland. The slump of the nearly 3,000 cubic yards of concrete was kept between 4 and 6 inches, and tests showed an average compressive strength of 7500 psi. As the temperature dropped during the 10-day job, more nonchloride accelerator was added to the concrete.