PROJECT
An 1,800 vehicle, six-level parking garage to be completed within one year of project start. Official start date was June 18 2001; half of the ramp opened April 1, 2002. Each pour of the total 22,000 cubic yards of concrete must meet or exceed 3,000-psi strength within 18 to 24 hours. The post-tensioned structure required approximately 3,750 gallons of Cortec® MCI® 2005 NS and 21,875 gallons of Enduracon HR Superplasticizer.
A calcium nitrite based corrosion inhibitor was used on the first two floors of the structure. It did not meet the required 24-hour minimum strengths, and also had shrinkage cracking. The project reverted back to the originally specified MCI® 2005 NS, and was able to meet the required specifications. Shrinkage cracking was eliminated with the use of the MCI® product, even in sub-zero temperatures.
CONCLUSION
MCI® 2005 NS reduced the effects of shrinkage and cracking, of particular concern for this project due to the fast strength gain the Enduracon HR produced. The project’s construction superintendent reported, in observations from under the decks, that much less cracking due to shrinkage occurred than he has seen on projects with other corrosion inhibitors. The concrete set up so uniformly, finishing, float work, and brooming operations were completed on one end of the deck while pouring continued on the other end. Even with the low water content, the mix exhibited excellent finishing properties, and there was no need for an evaporation surface retardant.
The predictable setting time, the early strength, and the concrete’s finishing quality decreased overtime and significantly helped to keep this project ahead of schedule.
PRODUCTS
