Dry compaction 3

[tain]

Hello guys. I want to ask about dry compaction for filling since the area is difficult to get the water (desert). The requirement
are:
1. Size of filling rocks < 500~600 mm
2. 1000mm per layer
3. 90% MDD for compaction
4. No of passing for compaction

I would like to hear any comment from all of you guys.. Thanks

 

[civilperson]

Dust control is almost always required by law so put water supply into the budget and lessen the compactive effort required by using optimum moisture in the fill.

 

[concretemasonry]

You are apparently talking about 1 metre lifts (40") in one lift with large rock unless my conversions are incorrect.

What kind of equipment do you forsee for compaction?

Do you have any idea if an moisture is available?

What method to you have available to test the amount of compaction/density?

Dick

 

[BigH]

Several questions come to mind about compaction of rockfill and the misplaced (in my opinion) about specifying a compaction level. You have not indicated if it is uniform size or is 500-600mm minus. Regardless,

1. In rock fill, you will have no binder - it will not have sufficient finer particles necessary to fill up all the voids - so that in every place you will, in effect, have a different material depending on how the material is distributed. You will also have large degrees of segregation.

2. If you have a required 90% relative compaction - relative to what? What tests are you running to get the MDD?? What material will you use given that every location will have a different degree of interlock - hence voids, etc.

3. How are you going to measure the in situ density after compaction? Digging a large pit, line with a impermeable membrane and fill with water for the volume?

4. Moisture control - with rock that big, any water you add will piss right on through.

I think that it would be better to specify a compaction sequence - such as 5 passes longitudinally using a 10 or 15 tonne vibratory roller, then 5 passes transversely, say. May then want to go back to a few passes of longitudinal.

 

[tain]

Hello everyone..Actually I'm quite new about all this thing. Definetely I never encounter about rock filling (500~600mm) before, especially for dry compaction. What I have been asked by my superior, to determine and study about dry compaction becoz the area for earthwork activity is massive (207.75 million cubic metres for cutting and 203 million cubic metres for filling approximately).Below is the formation for filling:

---------------------------------------------0 m (Top Level)
Fine & Coarse material will be mixed and spread and level to required thickness (300mm) per layer and compact to 95% MDD (modified proctor) (8 mil cubic metre)
------------------------------------------ 1 m (First Level)
The fill material will be controlled at <500~600mm diam. and spread & compact using wet compaction (1000mm per layer)
(25 million cubic metre)

------------------------------------------ 3 m(Second Level)
The fill material will be controlled at <500~600mm diam. and spread & compact using dry compaction (1000mm per layer)
(170 million cubic metre)

I need to know what kinda test appropriate for this activity. Like BigH said: Moisture control - with rock that big, any water you add will piss right on through.

I dont have problem with the first layer of filling.
The problem will arise during second and layer of filling.

How about mixing it with dune sand or other available material(soil)?

 

[muuddfun]

You will test for density by using Ring testing, we used 48 inch and 9 foot diameter rings for testing embankment fill for dams. There are several ASTM specs for them, look at D4914, ad D5030 for some info on that. Do a test fill and figure out what taget density you want to achieve then specify the no. of passes with compaction equipment etc. You wont have a compaction requirement that is say 90 percent of some value, that usually only applies to material less than 3 inches (75mm) and less. You will still want to add water as much as possible to lock into place some of the infill material forming the matrix with the rock, and to keep dust down.

 

[thegraduate]

for 90% max dry density, wont lab tests give you your required moisture content required to acheive this compactive effort in the field?

i assume your material will break up upon compaction.

is there any unconfined/confined groundwater around? i know on my side of the world under approx 70% of our deserts there is groundwater.

dont know the size of this project, but sourcing this might do some justice... although getting the required liscences would be a pain in the ass and it could be high in salinity.

dept. natural resources , or your equivalent might be able to help you further.

i'm interested to see the outcome of this thread, please update!

 

[DRC1]

20 inch stone is riprap. There is no compaction spec because there are no rollers designed to take that sort of surface. This is often placed with a clamshell, often underwater. Just place and go.

 

[dgillette]

If you have 500-600 mm rock, you won't be able to measure a a meaningful lab MDD, but if you only need (conceptually) 90%, you can probably get close enough with 3-5 passes of a D8 or larger. (If you have >400 million cubic metres to place, you will have bigger dozers than that on site.) With rock that size, you will need a ring at least as large as Muuddfun's nine-footer. And the testing technicians will curse the day your mama met your papa.

Rockfills for dams are routinely compacted with vibratory rollers. If there is finer material filling in the voids and/or the rock is soft (in which case there will be finer material breaking off), quite probably you can run vibratory grid or smooth-drum rollers.

What's all this for, and what's driving the compaction spec? Do you really need 95% compaction, or would it suffice to bring in some v. large rollers and do a test fill. Try two and three passes on three 1 m lifts, then see whether the test fill meets your needs for compressibility or whatever property is governing.