What is Post-Tensioning?
  Simply put, Post-Tensioning is a method of reinforcing concrete, masonry, and other structural elements. Post-Tensioning is a method of prestressing. Prestressed concrete or masonry has internal stresses (forces) induced into it during the construction phase for the purpose of counteracting the anticipated external loads that it will encounter during its lifecycle.
   There are two methods of prestressing. One is called pre-tensioning. This method consists of stressing the reinforcing inside of large steel buttresses, and then casting the concrete around the reinforcing. This method can only be done at a precast manufacturing facility and requires the completed prestressed concrete members to be trucked out to the job site and then assembled. The other method of prestressing is called post-tensioning. Instead of stressing the reinforcing inside of large steel buttresses at a manufacturing plant, the reinforcing is simply installed on the job site after the contractor forms up the slabs or constructs the walls. The reinforcing steel is housed in a sheathing or duct that prevents the steel from bonding to the concrete so that it can be stressed after the concrete cures (hardens). Using the post-tensioning method of prestressing enables a builder to get all the advantages of prestressed concrete or masonry (described below) while still enabling the freedom to construct the member (slab, wall, column, etc,) on the job site.