   SEARCH HOME Math Central Quandaries & Queries  Question from Curtis: I am trying to calculate the weight of a concrete cylinder. The diameter is 56" and the thickness or depth is 24". Can anyone help me? If possible I would like to see the formula as to how the answer was derived. Thank you Curtis,

You can use our volume calculator to find the volume of the cylinder but the weight is not as easy. The weight depends on the density of the concrete which varies considerably, depending on the aggregate used. There are some densities at http://hypertextbook.com/facts/1999/KatrinaJones.shtml. The densities are given in kilograms per cubic metre but you can ask Google to give you the weight in pounds. There is an example in my response to Daniel.

I hope this helps. If you need further assistance write back,
Harley

Curtis wrote back

Harley, thank you for the quick response. To further expound upon my question, as a general rule we use the following factor to determine/estimate the weight of concrete for removal purposes: 12.5lbs. x thickness x size. So in this example a 1ft. x 1ft. x 6" thick slab area weighs approx. 75lbs. Is there anyway to convert that to determine a cylindrical weight(knowing the diameter of cylinder & the thickness)?? Thank you.

Thanks Curtis, this is useful information. So if you have a rectangular slab to remove you multiply the length times the width, both in feet, by the thickness in inches and then by 12.5 to estimate the weight in pounds. If you measured the thickness in feet also then, since there are 12 inches in a foot you are estimating the density of concrete as 12 ×12.5 = 150 pounds per cubic foot.

So back to your original question. Your cylinder has a radius of 56/2 = 28 inches and a depth of 24 inches. Converting these to feet the radius is 28/12 = 2.33 feet and a depth of 24/12 = 2 feet. The volume of a cylinder is π × radius2 × height so the volume is

π × 2.332 × 2 = 34.21 cubic feet.

At 150 pounds per cubic foot that's 34.21 × 150 = 5131.3 pounds.

An even easier way to find the volume is to use our volume calculator.

Harley     Math Central is supported by the University of Regina and The Pacific Institute for the Mathematical Sciences.