How can a form with so many holes actually hold concrete?
Stay-form works surprisingly well in this regard. The concrete will actually have to be vibrated before an appreciable amount of grout will pass through the openings in the Stay-form. AMICO recommends that a three to five inch slump be used with Stay-form for best results. The contractor should vibrate the concrete until the grout blossoms through the Stay-form. This will leave a rough surface for the next pour when Stay-form is used as a bulkhead and provide reasonable assurances that all voids are eliminated. Stay-form is one of the few forms that allow visual inspection of the pour during concrete placement.
