Google concrete calculator and it will walk you through it.
Hello 2Late, I have done something similar. Let's start with floor prep. The building is existing with the cinder blocks sitting on the ground or on a footing? If they are sitting on a footing, then there is less worry. If they are sitting on the ground, then you do not want to be careful when disturbing the floor perimeter. Next, do you live in a cool or cold clime? Consider a thermal break between the gravel and concrete like sheets of closed cell foam (cool 1", cold 2"). If not no worries. Do you live in a wet place, the building low, high water table, etc.? Then there is a number of things you need to do. Consider a perimeter 3" corrugated drain line around the perimeter buried below the floor and gravel with an downward slope to daylight lower down away from the building. Is this building subject to water from activities inside? Consider a floor drain through the pad. If you are high and dry and have no such activities, then these steps can be skipped. Floor prep: Will this floor be subject to heavy equipment such as cars, lifts, etc.? If so plan on a 4" slab. If only light traffic 2", if medium 3". Depending on your slab thickness, dig down that depth, the thickness of any thermal break (1-2" if any), and approximately 2" of gravel compacted and level. Always use a moisture break consisting of 6mm plastic sheets (sold at HD). Water molecules are small and can make there way up through the concrete depending on the elevation and ground table. If you are doing a perimeter drain, the trench would be around the perimeter below the plastic. Next, expansion joints are good, especially if you live in a place with lots of temp swings. For 18x18', I would bisect into four sections that are 9x9'. However, you might forgo them if you live in a mild clime. If you are are doing a thick slab for heavy equipment, I would add wire mesh (also sold by HD) sunk about half way down in the pour. Decide on what kind of floor finish you wish to have and have those tools on hand for the pour (e.g.: magnesium floats for a smooth finish, etc.). The math: a 60lb bag of concrete fills .45 cubic feet (a little less than half a cubic foot). As all pours are three dimensional, I think in terms of width, length AND depth. In your case, you have width of 18', length of 18' and depth of 2", 3" or 4" depending on your slab needs. Since two dimensions are in feet and the one is in inches, we need to compare apples to apples. You can convert all dimensions to feet or all to inches. To convert all to feet, you would multiply the depth times .16, .25 or .33 for 2", 3" or 4" (this is the depth in inches divided by 12 - or the portion of a foot). OR you could multiple the 18' by 12 (216"). It is up to you which you prefer. Since the bags are in cubic feet, I would convert to feet (but either will work). The equation: 18'L x 18'W = 324sqft x depth (.16 for 2"D = 54 cubic feet, OR .25 for 3"D = 81 cubic feet, OR .33 for 4"D = 108 cubic feet). Divide total cubic feet needed for your slab (54, 81 or 108) by one bag (.45 cubic feet). In your example using the 2" slab which equates to 54 cubic feet, divide total by one bag: 54 /.45 = 120 bags (or 180 bags for a 3" slab, or 240 bags for a 4" slab). Pouring: Since you are doing a large pour, rent a mixer, have help to continually mix the concrete by the manufacturers instructions. It is important not to over water or under water the concrete. Always buy a few extra bags to have on hand as well. Consider 80lbs bags for less bag waste (they weigh more and equates to .6 cubic feet for the equations above. Just remember to have all tools on hand, extra bags, water, help, etc. before beginning. Try not to pour in the heat of the day. Mist the surface of the pour before beginning so that dry surfaces do not wick the moisture out of the concrete. Pour in one go as much as possible. After the pour: The concrete will have a setting time. Once the surface is set up to touch, keep the surface continually wet for about a week. Many people do not do this step. The longer you keep the concrete damp, the slower the concrete dries out and hardens. This allows for MORE and GREATER crystals to form in the matrix. This makes the concrete MUCH stronger. Keep out of direct sun and keep it wet!. You will avoid cracking and weak concrete. Just a note - when ordering concrete from a material vendor, they measure concrete in yards (27 cubic feet) and you will pay a premium price. In the above examples of 54, 81 and 108 cubic feet, this would equate to 2, 3 or 4 yards of concrete. Most vendor trucks hold 10 yards or more and will charge for short loads charging $10 to $15 per yard less than the truck holds. Do the math and compare. Hope that helps, Jeff
You need 66 bags of 60# or 50 bags of 80#. For that size I would call in a truck. Good Luck.
Thank you for your question. No, you would need a stucco mix or a Type-S Mortar Mix. Please contact us at 1-866-256-7404 if there is any more information that we can provide and resolve to your satisfaction.
Thank you for your question. Approximately 30 bags of material will be needed. Please contact us at 1-866-256-7404 if there is any more information that we can provide and resolve to your satisfaction.
The square root of 30 is about 5.477 (5.477 ft x 5.477 ft = 30 sf). Using 5.477 feet as both the length and the width, Sakrete's Concrete Quantity Calculator at https://www.sakrete.com/product-calculators, says you would need 22.2 of the 60-pound bags. Since you can't buy 0.2 bags, you could either buy 22 bags and be a little short or buy 23 bags and have a little extra.
Assuming you mean 2 feet by 11 feet. The Sakrete Concrete Quantity Calculator at https://www.sakrete.com/product-calculators says you need 8.1 of the 60-pound bags. Since you can't buy 0.1 bags, you could either buy 8 bags, and risk not having enough, or buy 9 bags, and have some extra.
Thank you for your question. For a 3ft wide x 10ft long x 3" deep area, you will need about 17 bags of SAKRETE 60 lb. Gray Concrete Mix. Hope that helps and thanks again.
That depends on where you live, and the weather conditions. as long as you are not too close to the edge of the slab, and you are just anchoring something to keep in place and not applying any major force on it you should be safe after 48 hours.