Cubic feet to Square feet
by trevor_fontaine on 08/09/05 at 20:29:36

Hi, I'm trying to estimate materials for a rock wall and need some help.  The wall is 80' long by 4' high by 2' wide so the volume would be 640 cu.ft.  The quarry says that the rock is about 1 foot high and is 1 ton per 35 sq. ft.  I've talked to several different people at the quarry and get conflicting answers on how many tons of rock I'll need for the project.

I need to figure out how many tons of rock I'll need for the wall.

Thanks!

Re: Cubic feet to Square feet
by Robert Fogt on 08/10/05 at 02:03:47

Their quote doesn't make much sense. You cant very well sell rock by the square foot.

What type of rock is it?  And is it crushed? Solid? I may be able to track down the data myself.

Re: Cubic feet to Square feet
by trevor fontaine on 08/10/05 at 09:21:55

The rock is called 'rip rap' which is basically colorado mountain granite in varying sizes.  The rip rap is broken up into random sizes from 5" to 18".  Here is a url to get a better idea of what I'm talking about.  [url]http://www.pioneersand.com/products/boulders_riprap.htm[/url]

When I build the wall there will be natural gaps in the rocks so the volume of the wall isn't exact but close.

Thanks alot the the help as the quarry isn't giving me a warm and fuzzy about their math skills.

Re: Cubic feet to Square feet
by Bruce Bradley on 08/10/05 at 18:53:03

640 / 35 = 18.285 TONS A SQUARE FOOT THAT IS A FOOT HIGH IS A CUBIC FOOT

Re: Cubic feet to Square feet
by Robert Fogt on 08/12/05 at 18:58:15

I looked up broken granite and it has a density of 103 pounds per cubic foot.

For that you would need:
640 cubic foot * 103 pounds/cubic foot = 65920 pounds

65920 pounds / 2000 = 32.96 tons

But its a fairly risky guess for the amount, since between 5" and 18" is a big difference. And my data just says "broken granite" so it could mean anything.

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