[TheForge] Coherex

[Jerry Frost]

I've been giving this a bit more thought. (I know, I sould've before sending
the last post. <sigh>)

We're talking about soils stabilization and there are a number of factors to
consider for any of them to work properly.

The biggest two factors for good stable soil is gradation and angular
material. Gradation is the %s of particle size. The idea is to have the
right amount of each size particle to fill all the gaps between the next
larger sizes. When I refer to a soil as "sandy, silty, etc." I mean the soil
has too high a % of the given particle size to be a "good" gradation.
Particle shape also plays a major role, round particles are like a bag of
marbles and even a good gradation can move around. Angular particles key
together like a jigsaw puzzle and even a poor gradation can be very stable.

Chemistry plays a part on occasion and there are a number of places where
the soils will NEVER pass: ASHTO, AMRL, ASTM, nor anybody else's standards
but compact hard as concrete, never go anywhere, don't get muddy, dusty,
etc. In one instance, pavement was a serious step down from the "dirt" road
but try convincing an engineer. These are USUALLY limey soils.

The job of water in soil's work is as a lubricant. You want enough water to
make the particles move easily but not so much it displaces particles and
leaves voids. The best rule of thumb for determining this is NO free
moisture under the compactor. If water pumps to the surface while compacting
it's too wet. Don't let anybody convince you otherwise, I did thousands of
compaction tests in the soils lab and plotted the density break just before
the free moisture showed in the flask. In thousands of tests, not one of
them got denser from excess water.

If you have a good soil gradation artificially stabilizing it should be
unnecessary except for dust control and a polymerizing oil raked and
compacted into the top inch or so works wonderfully. It won't take very much
either, a 0.10% at most so you'll want to thin and spray it prior to raking
it in. A polymerizing oil will also DRY and not be messy nor stinky like say
used crank case oil. You also won't have EPA after you. <grin>

I've also heard of people using diluted wood glue, Elmer's, etc. for dust
control but it's hear-say and I don't back it at all. Still, it's logical
enough for a little experimenting to maybe be worth it. Indoors I would
imagine.

The best and by far most effective stabilization and dust control is
pavement; cement, asphalt, cobbles, etc. Price and use is the prime
consideration.

Another of the basics is wet binding. (I don't recall the proper term, it's
been more than 20 years.) Wet binding is controlling the moisture content of
the soil; dry dirt blows, damp dirt packs and wet dirt flows. You must
maintain the PROPER amount of moisture to stabilize it, too little and it's
a waste, too much and it's a mud bog.

There are a number of ways to passively (you don't want to take the garden
hose to it regularly) control wet binding, calcium chloride for one, oil for
another and there are any number of other products. One of the major
conditions required for this to work is the % of fines. Wet binding does not
work well in sandy or gravely soils but works like a charm on silty or
clayey (love that word) soils. You can of course increase the $ of fines in
sandy and gravely soils to make it work. Just remember, wet binding soils
with salts creates a corrosive environment. You can also attract critters to
your home made salt lick.

Then there's cement stabilization, this works much better in sandy soils
than fine soils and once again, you'll have to increase the % of sand in
gravely soils. Cement stibilization is my favorite where it'll work. If all
you have to work with is sandy soils, a little portland cement will make it
compact beautifully.

This is what I did last weekend as a matter of fact. <grin> I had to raise
the floor level in the old buck pen to encapsulate any surviving Johne's
bacteria. We lost our goat herd to a Johne's outbreak two winters ago, the
land's lain fallow long enough the bacteria should be dead but in the most
heavily infected area I'm not taking any chances. After cleaning as much of
the old soil from the pen I wheeled about 10 barrows of dirty old road sand
in and leveled it a few inches above finish grade. Then I spread about 3/4
of a bag of type II portland cement on it and thoroughly raked it in with a
4 tine cultivating rake, then compacted it. After a little fine tuning the
finish grade, level, smoothe, etc. I sprinkled the last 1/4 bag over it and
raked it into the top inch or so then recompacted it.

I did NOT wet it down, the sand was slightly damp and the cement will absorb
moisture from the sub soils and air. There were enough fines in the sand
already it would compact reasonably well and hold, even dry. I upped the %
of cement in the top inch to make a harder surface for cleaning. It is NOT
concrete, a little pick work and you can dig right through it but it's far
better than a dirt floor.

You can cement stabilize soils with a number of things, lime is an excellent
choice for many uses and like the name implies you're literally
cementing/gluing the soil together. If it works I would put the wood glue
trick in this catagory.

For larger projects the method is to spread and level your basic soil and
evenly spread the cement over it, mix it with a roto tiller, relevel and
compact. If you need to add water, do it before you add the cement and mix
it thoroughly with the tiller, rake, etc. before adding the cement. Did I
mention adding the water BEFORE adding the cement? Yeah, it's important,
this isn't concrete.

I'm sure I'll remember more on the subject but I think that takes care of
the basics.

Frosty
------------------------
If it ain't forged
it ain't real.
Wrought iron is.
The FrostWorks

Meadow Lakes, AK.