lab dry density test 1

[lovethecold]

Is there a method to determine the dry density of a split spoon sample without resorting to the use of mercury or by measuring the dimensions? I don't like using mercury (I am highly accident prone), and some soils don't lend themselves well to cutting into nice even dimensions (ie: sandy lean clays with gravel).

Any suggestions would be highly appreciated.

 

[Rjeffery]

There is a paraphin (sp) method used for shrinkage limits that may lend itself to your application

The best way to test something is to squeeze it, slowly, until it breaks!

 

[GeoPaveTraffic]

I would never determine density off of a split spoon sample. Too much disturbance.

 

[lovethecold]

GeoPaveTraffic, in most instances I would agree. however, there are many soils where it is impossible to push tubes, and a density is desired to help determine potential settlements, etc. Indeed, the very soils we would like to have tubes are typically the soils we cant push tubes into. How do you typically determine dry density from field collected samples?

Rjeffery, thanks, I have read the method for shrinkage limits. I will look into the paraphin method as a substitution for determining density. As the most junior member here the decision won't be mine, but if there is an equivalent method that is acceptable, then hopefully I can get this changed.

 

[GeoPaveTraffic]

What type of soils are you trying to sample?

People have figured out ways of getting pretty much undisturbed samples from just about any type of soil. Like most things it is just a matter of time and money.

 

[lovethecold]

Yes, money can get anything. We drill mostly fat clay and sandy lean clean with gravel, probably 50/50 in regards to clay. For heavier structures we go into very dense (l00+ bpf) glacial till (sandy lean clay).

 

[GeoPaveTraffic]

As long as the gravel content is not too great and the size of the gravels is 1/2 to 3/4 inch I would expect to be able to get good Shelby tube samples from the fat clay and sandy lean clay.

May not be able to get much sample from the till, but then again probably don't need much in the way of a sample of the till.

Based on your ealier post, I assume that you have not able to get samples of the upper clays. This may have more to do with the driller than with the soil. Are you haveing trouble pushing the tube or getting recovery?

 

[fattdad]

I'm with GeoTrafficPave on this this one and fully understand the reply of "lovethecold". SPT samples are just too disturbed for any sort of meaningful determination of density. You'd never be able to argue standard of care if you met a problem by using those data.

If the soil is too dense for Shelby tube sampling, it's overconsolidated. If the natural moisture content is substantially lower than the liquid limit, it's overconsolidated. If the soil is granular, consolidation characteristics are not important (but soil modulus is). If all you can get for a sample is SPT owing to in-situ density/consistency, you can likely just evaluate the soil's response to loading using Es with correlation to SPT N-value.

You can also use a dilatometer. . .

f-d

¡papá gordo ain’t no madre flaca!