The Reusable Concrete Mixing Bag mixes a 40, 60, or 80-lb. bag of ready mix concrete in less than 1 minute. Place the bag over an opened ready mix sack, tip over the combined bags so ready mix is in bag, add appropriate amount of water (chart on bag), close bag using hook and loop cinch strap, then rock mixture back and forth for 45 seconds. Pour mixed concrete where needed.