New concrete passes PCAPP Test
March 30, 2009
Pueblo Chemical Agent-Destruction Pilot Plant workers have been testing and placing self-consolidating concrete, or SCC, that will be used in the walls of the Explosive Containment Room of the Enhanced Reconfiguration Building.
SCC is unique because it contains chemicals that allow it to flow freely as it is being placed without the use of vibration, a technique used in regular concrete placement.
In order for SCC to be used at PCAPP, two key parameters were tested. The first parameter, compressive strength, must be equal to or greater than 4,500 pounds per square inch. Thorough consolidation, the second parameter, means that concrete must be embedded around the steel, including rebar (reinforcing bar). With the help of Pueblo subcontractor Kleinfelder, who ensured that SCC met these standards, both parameters were successfully tested to ensure they conform to the required criteria.
Testing the strength of SCC involved crushing samples of hardened concrete using a compressive strength testing machine. In order to test consolidation, concrete was placed in a "mock wall" to simulate the walls of the explosive containment room. "While SCC was being placed into the mock wall, PCAPP workers were able to see how quickly and easily SCC flowed around the intricacies of the rebar and large embeds through a Plexiglas window installed into the formwork," said Steve Thieme, Bechtel site superintendent.
Since SCC has met the criteria set forth in the design requirements, its use is anticipated to be approved by the U.S. Army Element, Assembled Chemical Weapons Alternatives, which is the Department of Defense organization responsible for the destruction of the Colorado chemical weapons stockpile.