Is a special concrete mix used for ICF construction?
Generally walls will require 3000 psi concrete, or as specified by the engineer or building code. The maximum aggregate size is 3/4 inch (19mm) placed at a 5-7 inch (125-150mm) slump depending on manufacturer’s recommendations. However, because concrete is usually being pumped in place some contractors and concrete pumping operators may recommend a 4000 psi concrete because the addition of more cement makes concrete flow and pumping easier. Also if a 2-inch pump hose is used, a 3/8 inch aggregate (pea-gravel) will be required to avoid clogging in the hose. Concrete additives such as fly-ash, pasteurizers, water reducers, and others may also be considered to accomplish desired performance or goals.
