Concrete can be designed for compressive strengths from a few hundred pounds per square inch to over 4,500 pounds per square inch by manipulating admixtures, the amount of water in the mix, and the curing environment. Typically, 90 percent of the finished strength (hardness) of concrete is achieved within 28-days of the pour. But then something odd happens. Concrete takes a very long time, theoretically an infinite amount of time, to achieve 100 percent of its maximum strength. It follows then 20-year old concrete is a little stronger on Tuesday compared to Monday, if only infinitesimally so.

This background lesson in materials science is helpful in understanding the plight of a demolitions contractor who ran into a big problem while removing spalled concrete from the floors of several underground utility tunnels that was part of a larger $4,674,879 contract to repair a dry dock at the Puget Sound Naval Shipyard. The spalled concrete had to be removed from several inches beneath whatever rebar that became exposed. As it turned out, the hardness of concrete greatly exceeded the contractor’s expectations, leading to a differing site conditions claim valued at over $700,000.

In Appeal of Fuel Tank Maintenance Co., LLC, 2008-2 B.C.A. (CCH) P33,888, the contractor made a Type II differing site conditions claim (a condition “that could not be reasonably anticipated by the contractor from his study of the contract documents, his inspection of the site, and his general experience.”) The contractor could have easily made a Type I differing site conditions or defective specifications claim (i.e. Spearin doctrine) as well, because the contract expressly limited him to using a 15-pound jackhammer to remove the spalled concrete.

As it turned out, even 60-pound hammers were inadequate. A complicated and expensive hydroblasting method proved to be the only thing that worked.

The contractor brought his claim to the Armed Services Board of Contract Appeals (ASBCA) after it was rejected by the government’s contracting officer. The administrative law judges of the ASBCA were persuaded by the foreman and superintendent for the subcontractors who performed the actual work when they testified about how unusually hard the concrete became beneath the rebar. These witnesses testified to numerous broken hardened steel jackhammer bits and production rates that were nearly one tenth of what was anticipated.

The judges quickly dismissed the government’s argument that the contractor was at fault to the extent that it used 60-pound hammers instead of the specified 15-pound hammers. They correctly deduced that the heavier hammers should have made it easier, not harder, to demolish the concrete.

The judges were further disappointed by the government’s failure to conduct any type of meaningful investigation to verify the contractor’s difficulties and perhaps determine the cause of the unusually hard concrete.

In the end the ASBCA overturned the contracting officer’s denial of the claim and remanded the matter to the parties to negotiate the appropriate measure of damages and interest.