Concrete workers at the World Trade Center site were back at work Thursday.

Members of the Cement and Concrete Workers District Council agreed to return under the terms of their contract, which expired in June, after walking off the job Monday.

They also agreed to extend contract talks through August 16.

The dispute is over workers' wages and the use of non-union workers.

The walkout slowed progress at the signature One World Trade Center and the World Trade Center transit hub.

The strike did not affect the September 11th memorial set to open next month.