Why is the concrete limited to a placement height or lifts of 4 feet (1.2 m)?
To alleviate the pressure from the liquid concrete, the concrete is placed in layers or ‘lifts’. The first lift is limited to 4′ (1.2 m) of concrete around the perimeter of the building. This allows approximately one hour for the concrete to set-up before continuing with the next 4′ (1.2 m) lift. The lower lift provides support for the next lift as the concrete is placed continuously around the building in consecutive lifts to the top of the wall.
Do ICFs require a special concrete mix design?
The concrete is normal strength, minimum 2500 psi (20 MPa) per building codes. The mix design specifies a smaller aggregate and higher slump than concrete typically used for floors. Most Ready-Mix suppliers are familiar with an ICF concrete mix design.
How do you control voids in the wall?
The concrete mix is a high slump 5″- 6.5″ (125 mm – 165 mm) with a smaller aggregate size so the concrete flows easily. The person in charge of placing the concrete should watch the concrete flow throughout the whole wall to ensure there are no void pockets. Internal vibrating provides good consolidation, eliminating voids.