Computing the area a pile will cover

Stan in Oly, WA · May 22, 2015

Does anyone have a useful method for estimating the size of the pile different materials will make when delivered by a dump truck? Obviously, crushed rock will pile up higher than round drain rock, and damp top soil will pile up higher than either. What I don't know is how to estimate how high a pile a given material will make. Often it would be really handy to know that. Any ideas? And, thanks.

Stan

JRSutton · May 22, 2015

I don't have an answer for you - but I would think the best you could do is a loose approximation.

You need the angle of repose (the natural angle of the sides of the pile) for the material you're talking about - it varies by material, and the condition of the material (wet/dry - other stuff mixed in, etc). Gravel is between 30 and 45 degrees, but that's a big difference.

Just google angle of repose and maybe you can find some reliable numbers.

Once you have that, then it's just cone geometry. Easy enough to figure out. You'll have the figure for the cone volume - with the angle you should be able to figure out the height - and the area or the diameter of the bottom.

JCinKY · May 22, 2015

I agree with JRSutton, an estimation will be all you get.

That being said keep in mind you will know the volume based on the container its delivered in. All dump truck beds and dump trailers are fairly rectangular, thus LxWxH give you a rough volume.

And you know the height can't be any higher than the truck/trailer can dump. Just take material, wet vs dry, etc into account and use cone geometry to get close.

Everything goes out the window if the driver pulls forward to spread the load.

JRSutton · May 22, 2015

good point on the max height being that of what's dumping it.

but I also re-thought my answer - a dump truck dumps acorss the width of the truck, so it's not really a cone.

that makes me think there's more work in calculating it accurately than it's worth!

JMOR · May 22, 2015

(quoted from post at 17:10:50 05/22/15) good point on the max height being that of what's dumping it.

but I also re-thought my answer - a dump truck dumps acorss the width of the truck, so it's not really a cone.

that makes me think there's more work in calculating it accurately than it's worth!

eah! After he dumps it, measure it, the truck, moisture content, etc., then next time you will not only know, but will be able to give insight to others with nothing to worry about, :wink:

Charles in Aus. · May 22, 2015

The load is generally rectangular at the base as already noted . There is no real need for angular calculations , the height of the pile divided by two, times the base dimensions will yield a figure that is very close to actual volume .

Geo-TH,In · May 23, 2015

Stan,
If I understand your question, the size of the pile is determined by the density of different material? Like a ton of feathers will be a bigger pile than a ton of concrete. Both are still a ton, both have different densities.

Volume is area times depth. So to determine the area something will cover, you need to know the depth.

So refine your question, what's are you spreading out and how deep?
density of common building materials

cwtech · May 23, 2015

A truckload of water will not pile up very high, but the area of the "pile" will depend on the volume of the material being delivered.

In pondering your question, one would also have to take into account the slope of the ground where the material is being dumped, and also if wind will play a factor.

Another obvious question is whether the dump truck has a full load, and what is the volume of material being delivered. ....One cubic yard of material will not cover as large an area as 10 cubic yards.

I think it's time for another drink!

Stan in Oly, WA · May 23, 2015

I think several people misunderstood my question. Rereading it, I can see why. I think it wasn't a good question because you would have to know both potential height per volume and the angle of repose for each material that was likely to be delivered that way. I withdraw the question. Thanks, anyway.

Stan

showcrop · May 23, 2015

I drive a truck occasionally and if anyone were to ask me what was the volume of the load that I was dumping I could tell them pretty close. If the driver can't tell you, you are often buying the material by volume anyway, and it probably has it right on the delivery ticket.

Stan in Oly, WA · May 24, 2015

See, that's why I withdrew the question. I wanted to know if there was a handy way to estimate the AREA a pile of a known volume of material would cover. Apparently I stated it so unclearly that several people thought I wanted to know how to calculate volume. I thought it was obvious that, as you pointed out, materials delivered by a dump truck are almost always sold by volume---usually by the yard---so the volume is a given. The lesson for me is that nothing is obvious.

Stan

showcrop · May 24, 2015

(quoted from post at 09:15:55 05/24/15) See, that's why I withdrew the question. I wanted to know if there was a handy way to estimate the AREA a pile of a known volume of material would cover. Apparently I stated it so unclearly that several people thought I wanted to know how to calculate volume. I thought it was obvious that, as you pointed out, materials delivered by a dump truck are almost always sold by volume---usually by the yard---so the volume is a given. The lesson for me is that nothing is obvious.

Stan

Well, I would say that given the volume of material that the AREA that would be covered would be just as obvious.

Stan in Oly, WA · May 24, 2015

It's not, though. The area is going to depend on how high the material will stack. Manure or wet top soil will pile up really high, but pea gravel or round drain rock won't. Clearly, ten yards of material in a pile four feet high will cover a smaller area than ten yards of material in a pile half as high. It was a pointless question.

Stan

ss55 · May 24, 2015

I think the first response, by JRSutton, correctly answered your question. You need to know the angle of repose of the material to estimate how far the sides will splay outwards.

When a dump truck unloads, the height of the pile is limited to the bottom edge of the open (hinged?) tailgate. After the initial pile stops the flow out of the box, the truck slowly pulls ahead laying a quadrangle of material: height of the bottom edge of the tail gate, top edge the width of the box, and side angles at the angle of repose.

So, if you know the volume of material, the height and width of the pile and the angle of repose, you can work backwards to estimate the length of the pile. Remember all four sides will slay out at the angle of repose and the four corners will be the rounded at the angle of repose. The volume of the four corners combined is equal to a cone the height of the pile, and the front and back edges will be triangles the height of the pile, and the center will be a quadrangle. Clear as mud yet?

NoNewParts · May 25, 2015

I regularly get 10 ton of washed #2 stone.
1 pile, no spreading.
pile on the ground is slightly larger than when in the truck,
4' high...[i:63bca89ea0]and[/i:63bca89ea0] dimensions turned 90 degrees from when it is in the truck.

Computing the area a pile will cover

Stan in Oly, WA

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JRSutton

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JCinKY

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JRSutton

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JMOR

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Charles in Aus.

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Geo-TH,In

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cwtech

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Stan in Oly, WA

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showcrop

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Stan in Oly, WA

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showcrop

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Stan in Oly, WA

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ss55

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NoNewParts

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