Compacting gravel driveway

[dodge man]

If the gravel you are having delivered has fines in it I wouldn’t add any dust.

Gravel may be sold by the yard but they weigh it to get the number of yards. There is no easy way to get a volume of something like gravel so they use an average weight per yard.

 

[LouNY]

If you really want to do a good job compacting a gravel driveway, use a compactor like this or even a self propelled rubber tired compactor. They will do a better job then the steel drum compactors.

 

[stucknutz]

Depending on size of gravel and if it has dust or not. It wont pack even with a compactor.

Say #57 crushed limestone sure you can run over and "compact" it with a roller but once a car runs on it and turns it's tires that gravel is no longer compacted.

 

[alexinPA]

You’re basically wasting time compacting clean stone. The roller will smooth it out and make it look better but it will roll around again as soon as you drive on it. The stone dust or crusher run is the only way to make it lock together.

that's what i'm getting. It's called modified in my area. Just thinking about adding more stone dust for better compaction

 

[chim]

compact, then spread 1-2" stone dust and recompact

Worked as a laborer for a contractor who built A section of PA283 in Lancaster County when I was a kid.* On secondary roads that had to be redirected they used a thick bed 4" ballast and rolled it with a large vibratory roller. Then they dumped and spread screenings and worked them into the nooks and crannies with a grader. Rolled again several times with a crew of us laborers brushing the screenings around till the ballast wouldn't accept any more. That was in the late 60's and although portions of the main concrete road have been replaced, I think the side roads might still be original.

* Worked lots of places then. My tax returns looked like a listing of the local yellow pages My stepdad said I'd never amount to anything because of my job hopping. He was a lifetime Armstrong employee and it wasn't till I had 15 years or so with the company that he thought I'd be OK. Finally retired from there 2021 after 48 years. RIP Pop.

 

[bdhsfz6]

I'm just west of you near Honesdale. I have a 1.25 mile private gravel road which I maintain. I buy a product from Atkinson Materials, now a division of the H&K Group, near Hawley. It's called 2A modified and it has plenty of fines. I find adding stone dust isn't necessary. This of course will depend on individual quarry mix.

I found that even when compacted, stone dust on the surface is prone to shifting by wind & water, especially on a slope.

 

[Cycledude]

Where I live they started selling gravel by weight a few years ago, previously it was mostly sold by the yard.
My experience has been that it usually packs better if you can grade it and drive over it when it’s wet.
Around here there are a few different types of gravel and some types pack better than others but they are also more expensive.

 

[dodge man]

When I’ve seen gravel compacted on highway jobs it was always with a smooth wheel vibratory roller. It’s also possible to over roll things.

 

[paulsharvey]

That's why I time my products delivered at least a week after it rains. But in the grand scheme of things, how many gallons of water does gravel hold? 250 gallons is a ton. I've never seem dripping gravel, or crushed stone for that matter. But not what I ordered...

7% by volume, roughly

 

[paulsharvey]

This same stuff comes up every 3 months or so. Washed stone doesn't really compact unless your pushing it into the subgrade. Our OP said "crushed stone" which in my world is Not washed rock. Crushed implies multiple grades from fines upto maybe the size of a fist. Is that is the material, no need for fines. If what you call crushed rock is actually a clean gravel, yes, 100%, you'll want fines; BUT they need to be fully mixed into your base material, not just spread in surface.

Also, can't compact dust or mud, need your moisture right to get much compaction.

 

[paulsharvey]

that's what i'm getting. It's called modified in my area. Just thinking about adding more stone dust for better compaction

The ideal product should be pretty evenly graded (sized), from fines (powder) on up to fist sized material. Too "boney" or too much fines are both a negative. I would only consider adding fines if the was a issue, and still, I wouldn't add just fines; I would scarify the surface and add some more crushed rock.

 

[LouNY]

When I top dress my driveway I get screened gravel, commonly call #57 or #67 or fine screened. My driveway is too steep for crusher run and fines, the dust gets carried away to easily by the rain and you are left with loose rock.

 

[2manyrocks]

A highly experienced road builder here told me that there is a difference in compaction between two quarries in our area. The material from one of them is more granular and doesn't compact well. The other quickly sets up to a firm consistency.

 

[paulsharvey]

Each real rock mine is going to pull proctors, and there can be a pretty significant difference in results; based not only on the rock, but the crusher, as well as clay content. You can see anything from maybe 108 pcf max density to 125+ pcf max density from mines just a few miles away.

PCF= Pounds per Cubic Foot

Also, some over burden ends up in the rock too, and that affects things as well.

 

[Egon]

Handbook on basic compaction.

https://www.multiquip.com/multiquip/pdfs/Soil_Compaction_Handbook_low_res_0212_DataId_59525_Version_1.pdf

 

[paulsharvey]

I am slightly hesitant to say this, because I haven't used your material; but generally speaking; if you pick up a fist full of material, squeeze it, you Should be able to make a ball that kinda sticks together, but when you drop it, it completely falls apart. If you can't kinda make a ball, then it's too dry; if the ball sticks together when dropped, too wet. Needless to say, this changes based on material type, and this would not apply to a gravel type material.

 

[paulsharvey]

So, AlexinPa, check out "Prices of driveway paving" thread, I tagged you in it. There are literal essays written over there, on driveways, compaction, materials, ect. There are also about a dozen more threads on this specific topic, and way too much to type out on a phone again.

 

[Alan W.]

Ive noticed that road base is called by different names depending on your location.
Here we use DGA which stands for dense grade aggregate. If you want to get a high level of compaction then you get DGA that has been run through a PUG mill. This is basically mixing water into the DGA. This mixture will compact like concrete.
All rock in our area is sold by weight and the price varies by the size.

I sure prices are up some this year but these prices were good this spring.

I am not sure of your existing drive but when building a road you first cut out all the organics, meaning the topsoil is removed to the clay. Fabric is laid followed by #4s then the DGA. This is an over simplification of the process and doesn’t address drainage.

 

[dodge man]

A couple of more useless tidbits on compaction. Most of the time the actual strength of the compacted material isn’t important. The goal is to compact it so it doesn’t settle. Even under buildings the actual strength isn’t that critical unless it drops below a certain threshold, than something needs to be done, such as wider footings.

My biggest problem with my gravel driveway before we paved it was it turning to soup when the frost left the ground in the spring. If you get a good solid base going you can top it with something like chips which won’t compact but will be cleaner.

 

[paulsharvey]

What I think causes a lot of problems with these things, step 1; define the scope/goal/budget, and then work from there.

What I mean is, function vs pretty; the $2000 fix or the $20,000 fix, are we wanting are low clearance corvettee to stay clean and not rub, or are we driving a suv/truck. I really think your material will be 100% fine, exactly the way you planned it, and I think adding additional fines is an unneeded expense, and could possibly make the material worse, dustier, and more prone to washing. It would, however, probably improve ride quality and appearance.