Building your own concrete slab, patio driveway or walkway is an excellent home improvement and most diy home handymen are capable of completing this type of project. All that is required is some knowledge and the right tools.
Square or Rectangle Concrete Slab
Circular Concrete Slab
Concrete (Sonotube) or Column
Download a free automatic ready-mix, by the yard and quantities required of 60 lb. and 80 lb. pre-mixed bags - concrete calculator - (you must have Microsoft Excel or other compatible spreadsheet program)
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Information on hand mixing concrete.
It should be noted that cement, is one of the 4 items that makes up concrete. Concrete is a mixture of cement, aggregate, sand and water.
Square or Rectangle Concrete Slab:
Notes:
- Pre-mix concrete comes in bags that are 60 lbs. and 80 lbs.
- A 60 lb. bag provides 0.45 cubic feet of cured concrete.
- A 80 lb. bag provides 0.6 cubic feet of cured concrete.
- If you have concrete delivered it is sold by the yard (which is a cubic yard = 27 cubic feet).
Following are the formulas to calculate how much concrete you will require for a square or rectangular shaped pour:
L (feet) x W (feet) x T (inches) ÷ 12 = cubic feet of concrete (CF)
Number of bags of concrete needed:
CF ÷ 0.45 = number of 60 lb. bags
CF ÷ 0.6 = number of 80 lb. bags
Number of cubic yards of concrete needed:
CF ÷ 27 = cubic yards
L = Length in feet
W = Width in feet
T = Thickness in inches
CF = Cubic feet of concrete
Example:
A patio 10' long by 8' wide - 6″ thick
10 x 8 x 6 ÷ 12 = 40 cubic feet of concrete
10 x 8 x 6 ÷ 12 = 40 cubic feet of concrete
40 ÷ 0.6 = 67 (66.7) 80 lb. bags of concrete
40 ÷ 27 = 1.5 cubic yards of concrete
Circular Concrete Slab:
Notes:
- Pre-mix concrete comes in bags that are 60 lbs. and 80 lbs.
- A 60 lb. bag provides 0.45 cubic feet of cured concrete.
- A 80 lb. bag provides 0.6 cubic feet of cured concrete.
- If you have concrete delivered it is sold by the yard (which is a cubic yard = 27 cubic feet).
Following are the formulas to calculate how much concrete you will require for a circular slab:
3.14 x r (feet) x r (feet) x T (inches) ÷ 12 = cubic feet of concrete (CF)
Number of bags of concrete needed:
CF ÷ 0.45 = number of 60 lb. bags
CF ÷ 0.6 = number of 80 lb. bags
Number of cubic yards of concrete needed:
CF ÷ 27 = cubic yards
r = radius of the circle in feet (1/2 of the diameter)
T = Thickness in inches
CF = Cubic feet of concrete
Example:
A circle 6″ thick where the circle has a radius of 5.5' (11' diameter circle)
3.14 x 5.5 x 5.5 x 6 ÷ 12 = 47.5 cubic feet of concrete
47.5 ÷ 0.45 = 106 (105.6) 60 lb bags of concrete
47.5 ÷ 0.6 = 80 (79.2) 80 lb. bags of concrete
47.5 ÷ 27 = 1.8 cubic yards of concrete
Concrete Sonotube , Column Or Round Footing:
Notes:
- Pre-mix concrete comes in bags that are 60 lbs. and 80 lbs.
- A 60 lb. bag provides 0.45 cubic feet of cured concrete.
- A 80 lb. bag provides 0.6 cubic feet of cured concrete.
- If you have concrete delivered it is sold by the yard (which is a cubic yard = 27 cubic feet).
Following are the formulas to calculate how much concrete you will require for a circle, tube or column shaped pour:
3.14 x r (inches) x r (inches) x H (inches) ÷ 1728 = cubic feet of concrete (CF)
Number of bags of concrete needed:
CF ÷ 0.45 = number of 60 lb. bags
CF ÷ 0.6 = number of 80 lb. bags
Number of cubic yards of concrete needed:
CF ÷ 27 = cubic yards
r = radius of the circle in inches (1/2 of the diameter)
H = Height in inches
CF = Cubic feet of concrete
Example:
A column 8' high where the column has a radius of 5″ (10″ diameter tube)
3.14 x 5 x 5 x 96 ÷ 1728 = 4.4 cubic feet of concrete
4.4 ÷ 0.45 = 10 (9.8) 60 lb bags of concrete
4.4 ÷ 0.6 = 8 (7.3) 80 lb. bags of concrete
4.4 ÷ 27 = 0.16 cubic yards of concrete