How much cement?

Question

I have a hole 43" deep and about 8-10 inches across. A pipe about 3" in diameter is also going in there. Is two 80 pound bags of ready mix enough?

Answer 1

here's how you figure it out:

area = pi x r^2 = 3.1416*(5"^2) = 78.54 sq in
vol = area * depth = 78.54 * 43 = 3377 cu in

do the same for the pipe, and subtract:
3.1416*(1.5^2)*43 = 304 cu in

3377 - 304 cu in = 3073 cu in

cu ft = cu in/1728 = 3073/1728 = 1.78 cu ft

each 80# bag makes .67 cu ft, so
1.78 cu ft / .67 cu ft = 2.65 bags

with waste, you'll need 3.

Answer 2

Perhaps; if you intend to back fill; given the fact that an 80 pound bag equates to approx 1.5 CU. FT.

Answer 3

Thinking your short a bag

Answer 4

no it's not enough. if your measurements are correct, you will need at least one more bag.

Answer 5

Plenty, two 60's would work.