September 28, 2015
A 20 ft x 12 ft x 0.25 ft (3 inch) application will require 60 cubic feet of concrete, which is 133 1/3 60 lb bags of Concrete Mix. Note that a typical slab is 0.33 ft (4 inch) deep, which would require 80 cubic feet of concrete, or 178 60 lb bags of Concrete Mix. Yields will vary based upon waste, uneven subgrade, etc. For a job of this size, it will be crucial that you have sufficient equipment and man power to either allow you to pour the entire application before any of the material has set, OR pour sections that are separated by expansion joints before any of the material in that section has set. If some of the material sets before subsequent bags are poured, a cold joint will form. A cold joint is caused by the inability of the product to intermix between bags, and prevents the slab from being a single, solid mass. A cold joint may cause problems ranging from a simple aesthetic issue, to as serious as potentially allowing for water intrusion into the cold joint, which may eventually lead to concrete degradation. Please contact the QUIKRETE® Technical Center directly at 1-800-282-5828 if you would like to discuss.
0out of 0found this answer helpful.