It’s very easy to figure out how much concrete you’ll need for a concrete project around your home. Regardless of the size, you need to calculate the volume of concrete in cubic yards before ordering the mixed concrete or bags. How much would you need for a 10-foot by 10-foot project?
The Cubic Yards Of The 10 x 10 Slab
To get the answer in cubic yards, multiply the length (10 feet) by the width (10 feet) by the depth. The depth is somewhat trickier, so we’ll use a standard thickness of four inches for this slab. If the 10 x 10 slab is going to have to withstand very heavy traffic, you should go to five or six inches, but we’ll say this is a recreational slab. Four inches is 0.35 feet, so now, our equation is 10 x 10 x 0.35.
Now, we divide this by 27, which is the number of cubic feet in a cubic yard. The final answer is 1.3 cubic yards, but we’re not going to try and get only 1.3 cubic yards of concrete. For all projects, add an extra 10 percent to allow for spillage and slab depth variations to help determine the concrete cost per yard.
The Strength of The 10 x 10 Slab
You also have to determine the type of concrete needed for your project. If you’re going with a ready mix, ask the proportions of the best mix for your project. All concrete consists of three simple ingredients: cement, aggregates like sand or gravel, and water. It’s the proportions of each that determine the strength of the project. For a 10 x 10 slab, we’d suggest a mix with a capacity of about 4,000 pounds per square inch, or psi. This is basic for residential projects, and it can withstand traffic and support heavy loads.
Here in London, we live in an area with harsh winters and brutal freeze/thaw cycles. To make sure the concrete survives these cycles, we need to account for the right air entrainment in the concrete. Air-entrained concrete has billions of tiny air pockets that act as little chambers for water to freeze into, relieving internal pressure on the concrete in freezing weather. Air entrainment of five percent per volume should help the concrete withstand the damage that comes with freeze/thaw cycles.
How Many Bags of Concrete Is Needed For A 10 x 10 Slab?
If you’re doing the mix at home, you’ll need to know how many bags to buy. A 60-pound bag yields .017 cubic yards, and an 80-pound bag yields .022 cubic yards. For a 10 x 10 slab, you would need 77 60-pound bags or 60 80-pound bags. If we add an extra 10%, that’s an extra 8 60-pound bags or 6 80-pound bags.
Whatever the size of your project, use the formula above to calculate how much concrete you’ll need!