In the last post we went over the proper concrete mix for insulated concrete form walls. Depending on the forms’ size and the concrete core width, the concrete aggregate size and slump should be adjusted accordingly. The ultimate goal is to get the correct compressive strength for the concrete as specified.
The concrete should be placed in 4′-0″ lifts to ensure proper concrete consolidation. Typically if there is more than one concrete pour per project, the walls are poured a story at a time. Concrete is placed in 4′-0″ lifts using several passes around the perimeter of the building plan, until either the top of the wall is reached or until the first pour is completed. Concrete should be placed below every window opening through the opening left in the sill of the window buck.
Most builders have found that an overhead boom pump truck is the most efficient method to place the concrete in the walls. With the overhead boom pump truck, it is important to slow the velocity of the concrete by reducing the diameter of the hose to 3″ near the end of the line.
While placing the concrete, the ICF Conctractor must keep a close eye all the time on how the concrete is flowing through the forms and around rebar. Be sure the concrete is not getting hung up on rebar or any embedments.
During cold and hot weather, the concrete mix may need to be adjusted to modify its flowability and the rate of concrete placement may also need to be adjusted.