Compactability

[Tatsu]

Hello,

say, I have fine material of which strength is very stiff clay to extremely weak rock (S5-R0). I would like to build a soil structure, by compacting it. Is any method available to figure out how easy/difficult the compaction would be ? Do you think I can say something from Standard/Modified compaction test ?

Thank you in advance !!

 

[msucog]

that is a slippery slope my friend. may i ask the particular reason why you're going out on that limb?

 

[CMTatTerracon]

Well it really depends on what your specs call for. If the soil had a lot of shell or rock in it I would run a 6" standard proctor. If not I would go with a 4" standard. Get your densities and your water content. Keep in mind to reach your compaction easier in the field its better to use a Sheep's Foot roller rather than a smooth drum roller. What is the soil being used for?

 

[Tatsu]

Thanks for the replies.

I am talking about a site in tropical region. I see thin overburden of laterite and thick completely to highly weathered bedrock underneath. I would like to use the weathered part to build embankment. Thus I have to know how compaction would be and how much material we can borrow. It depends on our specs and compactor we gonna utilize after all, if there is no popular way. I better talk to manufactuerer of compactors ??

Cheers,

 

[msucog]

it sounds like you're outside my realm of knowledge...i'd guess "big compactor, thin lifts at optimum moisture contents". that probably does not help your scenario. good luck.

 

[VAD]

It seems to me that you can use both laterite and weathered rock to build embankment. I presume that you will be producing a crusher run stone with about 3 inch max size from the weathered rock, which should be granitic in nature. Steel wheel rollers are often used -20ton with vibratory capabilities. Observation during compaction and proof rolling are best. If you wish some values try the large mold with a wooden base plate and a Kango Hammer to densify the material. Would give some idea of densification from loose state to a compact state. Adding water during compaction is often the best approach in getting maximum densification. Be careful not to overwet as water can soften subgrade if clayey. You can use nuke to check no of passes and density with addition of water. When curve of no of passes versus density drops off that would be requirement for particular compactor. Usually a compaction train is specified with some pneumatics. Whatever you do in your trial re compactors, these have to be kept the same during production compaction or the relationship may change.

Hope this helps a bit

 

[dgillette]

A test fill is the best way. Just got back from a site in Taiwan where they want to build a dam core from weathered very soft mudstone. A little experimenting with moisture content and lift thickness got them what they needed from a Cat 825 - good density and good breakdown of the particles. The data were provided to bidders.

Of course, if you can't seem to get your desired compaction with an 825, it's probably time to check your data.

DRG

 

[BigH]

dgillette - hope you enjoyed Taiwan. I had a colleague from Indoesia (South African) who went to work there for a while - large fill to be made of tunnel waste rock. One point to remember, too, is that weathered rock/residual soil continues to weather with time. What kind of long term effects might be felt as the rock degrades to clayier residual?

 

[dgillette]

Big H - Taiwan was a good trip. Friendly people, nice scenery, interesting work, too much food and Taiwan Beer (the only brand there seems to be) for two solid weeks. It's true what they say - snake soup tastes just like chicken (except it has bones like a catfish), and durian (or liolian) tastes like roadkill custard.

Not real worried about the mudstone at my site doing much more over time. They got it pretty well broken down with the 825 (low measured K in falling-head test), and it was silty-clayey sedimentary rock so I don't think it will undergo much change in minerology in human time. Once it's compacted in the core, it probably wouldn't matter anyway. Or was your question about long-term effects referring to Tatsu's laterites? (I know very little about them.)

 

[BigH]

Yeah, durian is a stinker; it's "BIG" in Indonesia (my wife's area for example) but thank god not up where I am now. Now, we have to worry about avian flu.

My comments about continual breakdown was a general one that one should think about. If you have considered it and made a conclusion, then fine!

 

[Tatsu]

Thank you for the replies, Falks.

Test fill has to be done prior to construction for sure. It is at pre feasibility stage at this moment. I guess best I can do now is to make sure the material can be densified well by proctor test, and get basic properties such as shear strength, k, wopt.. those kind of things.