ASTM D4944 Standard Test Method for Field Determination of Water Content of Soil by the Calcium Carb

[jrl802]

We have an earthfill embankment job were we are providing a method spec for compaction. The spec only allows for CL and CH materials. So we specify equipment, weight, pressure and number of passes. It is being recommended that we use the above referenced ASTM and associated equipment to performe field moisture testing to ensure some level of proper moisture control.

Any experience with these testing methods out there? Types of fills? applications, etc?

 

[oldestguy]

It has been many years since this 91 year old used one of these milk bottle shaped devices adapted from the foundry business where sand is compacted for form a mold for melted steel (Speedy moisture tester?).. As I recall for clays the standard sample size had to be cut in half to have the result fit within the moisture content gauge range in the bottom (20%). That reads out on the basis of wet original weight, not dry sample weight, requiring a correcting chart. However, the device worked fine and I do not recall any calibration problems as one has with nuke methods. This then permitted some rapid testing, not causing any delays for the contractor (as with a no good test zone already buried when an answer comes from the lab).

 

[Ron]

As OG noted, this is the Speedy Moisture Meter test method. It works fine in sands and sandy clays; however, you have to be careful that cohesive materials are broken up in the test process to get an accurate moisture content. You should also "calibrate" it against oven dried moisture on the same material. Develop a calibration curve that is material specific.

Another caution....the instructions say to put the calcium carbide in the lid and the soil in the bottle. Don't do that and here's why.....you can wipe the lid out after each test so that the soil is not contacting any calcium carbide before sealing the lid to the bottle. If you drop the soil into the bottle, there's always a chance for residual calcium carbide to be in the bottle, which will then react and throw off your moisture content. It doesn't seem like much, but keep in mind the sample size you use is very small, so even a little variation will throw things off.

Another caution....when calcium carbide is put in contact with moisture, it produces acetylene gas (that's what the meter measures...reaction gas pressure). The gas is very flammable so warn any smokers who might use the device that they shouldn't smoke when using the device.

Given that, it is a good and convenient method to use in the field.



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[GeoEnvGuy]

Your building an embankment you should be getting a proctor for the compacted clay and qc with a nuclear densometer for the dry density and moisture content in your specified low and high plasticity compacted clay. If a nuke is not available you can go old school with a sand cone and oven moisture content or cheaper microwave moisture content ASTM.

I also have seen a vendor try and promote electrical density meters which would not be subject to nuclear restrictions.

 

[fattdad]

Speedy moisture works. Not commenting on precision? I also think there are limitations on clay - not sure to what extent?

I guess I'd wonder the intent? If you are making a method spec and the borrow is coming from the site, you should already know the water content of the formation. Sure it'll change a bit during transport and replacement, but making a method spec, would usually accompany a test fill. If using a test fill, then that test fill program could include some one-points for comparison to the lab proctor and some better water contents.

Heck, even a frying pan, triple beam and Coleman stove would be another way to contrast Speedy to water content for your clay?

In the end, you should have a pretty good idea of performance.

f-d

ípapß gordo ainÆt no madre flaca!

 

[oldestguy]

Well with a simple question I am amazed at the digression that comes here. Question asks your experience with this device. That's all.

 

[fattdad]

I'll take that as an unwarranted dig and will remain confused.

f-d

ípapß gordo ainÆt no madre flaca!

 

[BigH]

What are your material specs? other than CH or CL? Find it strange that you wouldn't accept MH and ML with certain provisions on the minimum index of plasticity and liquid limit. Do you have a spec on the difference of the water content of the placed material and OMC? Which OMC? Standard? Modified? Equipment? Will you be taking moisture contents from the borrow area or from as it is on site? Makes a difference on how much time you have to get a moisture content - you might be able to get away with 12 hours instead of 24 if you can show that the difference of the two is small - you need not be exact to the nearest 0.1% usually. And who is responsible for the borrow pit? A number of things to think about.