Post Tensioned Challenges

Wrecking Corp of America has recently completed demolition and excavation work on a 250,000 ft², 10 storey post-tensioned building at the Tyson Corner site at Liberty Crossing in McLean, Virginia. The building was the former home of Nextel and was owned by Peterson Company, with general contractor for the job being Clark Construction Group, based out of Bethesda, Maryland.

Post-tensioning is a method of concrete reinforcement that involves the use of steel cables (tendons) that are tensioned after the concrete hardens. In use since the 1970s, only a few post-tensioned buildings have been demolished. Wrecking Corp has in fact already deat with six buildings of this type in the last few years.

The main problem that the company had to be prepared for is that such buildings have the potential for a sequential collapse once some of the tendons are de-tensioned. The cables are also dangerous in themselves because of their rubber band like nature and are also difficult to process.

As part of the six-month project, Wrecking Corp also excavated 100,000 yd³ of soil and 20,000 yd³ of backfill from the site.