1. Fill in any low areas in the forms with gravel, broken brick, or
chunks of concrete block; this will also reduce the amount of concrete
mix needed. Work the mix in and around all rubble thoroughly. Make
sure the rubble is placed back from the form sides so it will not break
through the concrete surface.
2. It is important to mix the entire project at one time. Overfill the
forms slightly, then work the concrete in and out with a shovel to
compact the mix and eliminate air pockets.