Determining clay compaction value in lab. 1

[PatKiewit]

Hi !
I have been a long time lurker of this forum. Here is my first post.

I want to know how can I find the maximum compaction value (Proctor) of clay in a lab. Do I proceed the same way as standard soils with a mechanical Proctor hammer? Or is there a different procedure.

Thank you for your inputs !

 

[PatKiewit]

Found it !

ASTM D-698 Method A

 

[Ron]

Not so fast there Pat! Yes, you have found the typical standard method used for clayey soils; however, when you do that test, be sure you "pre-condition" the samples to the moisture content you want for the test, otherwise, you'll get screwy results. The way I have typically done that in the past is to mix the soil with the amount of water required for the moisture content needed in the test, then cover the container and let it sit overnight, to get better dispersion of that moisture through the specimen.

 

[PatKiewit]

Good point Ron!

Thanks for the tip !

 

[BigH]

One of the problems with the standard proctor is that it compacts by dynamic forces - This might lead to erroneous results - clay is "densified" by kneading action. Lumps of clay - and you probably would be placing lumps - dug out of a pit - they will not compact in practice like in a lab where you pulverize the lumps, condition the clay, etc. Contractor in India used a smooth drum roller and we ended up with packed lumps . . . If I remember correctly, the Harvard Miniature Compaction test more resembles the kneading action of a sheepfoot roller (or, if in Thailand, an elephants foot!!)

 

[dgillette]

BigH - See this article by Richard Meehan:

http://www.stanford.edu/~meehan/flood/useless.html

Wait until the off season, and hire all the local farmers to bring their water buffaloes in. Forget elephants.

I agree that the Harvard Mini should provide a more realistic duplication of the compaction process. The biggest problem is that it is........miniature.

Test fills are often the best way to go if circumstances permit.

 

[BigH]

dgillette- I was well aware of the point made about elephants - although I hadn't seen this article. I had read Meehan's book- a fascinating one. A prank ...