A consultant hired by the City of Denver has recommended expanded testing of the concrete at Denver International Airport in order to check for the same conditions that have delayed the $960 million Jeppesen Terminal renovation by an estimated 38 months, according to CBS 4 Denver. Concrete-related delays reportedly have helped drive up the cost of the project from its original budget of $650 million, but airport officials have yet to confirm the new figures.
The consultant has recommended that, in addition to the terminal, concrete testing should be carried out at DIA's parking structures, garages and tunnels to check for alkali-silica reaction (ASR), also known as "concrete cancer" because of the swelling, cracking and weakening associated with the condition. The consultant also recommended that this testing be repeated in five years. So far, the terminal's concrete has shown traces of ASR but not to the extent that it would cause safety issues or prevent safe use.
Airport officials said safety is their primary concern and that it is too early to determine the impact, financial or otherwise, if the additional testing determines the presence of ASR.
In a December report, joint venture contractor Great Hall Partners said they had come across concrete that was weaker than what the airport specified when they entered into an agreement for the terminal renovation. Of particular concern are areas where steel erection is to be performed. Concrete strength is critical in that application because it must support the steel and accompanying structure above.
More than a decade ago, DIA had to replace approximately $11 million of runway concrete because of ASR, the freeze-thaw cycle and the damage caused by deicing agents. The airport was able to save money on the replacement, however, by substituting individual 20-square-foot slabs where necessary instead of tearing up large sections of the runway.
Last month, a DIA spokesman told The Denver Post that Great Hall and the airport were still in negotiations about how to deal with the extra cost and delays due to the concrete and other issues that have arisen on the project and won't likely see a resolution until summer. If it does turn out that the concrete cannot safely support the weight of planned construction — an outcome that is highly unlikely since no significant amounts of ASR have been found in the terminal — the airport and Great Hall might have to consider design changes or other departures from the original plans.