November 16, 2015
An 80 lb bag of QUIKRETE® Concrete Mix yields 0.6 cubic feet of concrete when placed. For a 10 ft x 20 ft area that is 0.33 feet (4 inch) thick, 66 2/3 cubic feet of concrete, or 112 bags (of 80 lb each) would be required. For a 10 ft x 20 ft area that is 0.42 feet (5 inch) thick, 83 1/3 cubic feet of concrete, or 139 bags (of 80 lb each) would be required. 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 application 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. Additionally, if temperatures are 50 dF in day, or near freezing (32 dF) at night, you must take cold weather precautions. Store the bagged concrete in a warm temperature before use, and use warm (not hot) water to mix. Protect the concrete from freezing for at least 3-4 days for a regular setting concrete using plastic sheeting, insulated blankets, or other means. If these preventive measures cannot be taken, it would be best to wait for warmer weather. Please contact the QUIKRETE® Technical Center directly at 1-800-282-5828 if you would like to discuss.
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