Oversize on Proctor Test

[BigH]

G'day Mates, again.

This new job is coming with a number of "issues" not the least of which is Russian standards vs ASTM standards. Very interseting take on things.

The Contractor will be placing loam material (0 - 200 mm) for the core and is supposed to do an ASTM Proctor on the material. 85% of the time, approximately, the gradation shows less than 30% oversize (19 mm). I realize the strict following says not over 30% but interestingly they do not say 30.0 percent which would intimate that given one significant figure 34% could be considered - technical point. From a practical point, thouogh for the standard purists, would 31 or 32% be something that you would take them to task?

I have suggested to the Contractor, given that the loam will be "variable" in gradation - take another sample or two to see if they just happened to have picked a bony location to sample.

Thoughts?

If any are interested contact me for the "Russian" method of determining the maximum density of rockfill.

 

[jdonville]

I'd say it depends on the amount of borrow to be placed vs. available, and required temporal and spatial frequencies of sampling of that borrow material.

As for how much oversize is too much, that is where engineering judgement comes in. If the spec is reasonable in your opinion and experience to limit the amount of oversize material, then it ought to be enforced. If the spec is unreasonable in your opinion and experience, then the you ought to raise the question with whomever generated the spec (but still be prepared to enforce the spec as is, pending the Owner's response, and say to the Contractor "I've asked the question and it appears that Management just wants it that way. Sucks for both of us.").

 

[Panars]

I would probably do the same as you, with taking another sample.
I think you could also remove the oversize material and then do a correction for it.
We would do a one-point proctor and use a family of curves to determine maximum dry density. If the material had 10 to 25% retained on the 3/4" sieve, we would then use an equation to adjust the maximum dry density. I came up with a nomograph that could be used in the field for the mathematically challenged. Coming up with that nomograph was a lot of fun for me.
[URL unfurl="true"]http://www.dot.state.oh.us/Divisions/ConstructionMgt/Specification%20Files/1015_01182019_for_2019.pdf[/url]

 

[Ron]

Older versions of the ASTM Proctor standards handled oversize corrections better than later versions. Take a look at a version from the early 80's and compare.

I see no issue with slight deviations from the 30% criteria, probably up to 33% or so.

 

[fattdad]

my approach:

Take borrow and run it though the 3/4 sieve.
Run a Proctor (your choice) in the large mold.
Obtain max and optimum. Recall that this is for the sieved material.

Go in the field with a 3/4 sieve.
Run a field density test.
Dig out the soil. (Now if it was a sand cone, you'd already have the hole.)
Run the soil through your 3/4 sieve.
Determine the percentage oversize from your test location. Let's say it's 20 percent, by dry weight. (Let's ignore the water content on the oversize material.)

Knowing the specific gravity, you'd calculate how much idealized volume represents the oversize. Subtract that volume from 1 cf and determine the density of the non-oversized material. Compare that to your proctor.

Hopefully, that makes some sense?

f-d

ípapß gordo ainÆt no madre flaca!

 

[BigH]

Thanks all - appreciate the comments - might try to get the Contractor to do what you suggest Fattdad. Unlike FERC, the Contractor here, EPC, is fully in charge of Quality.

Haven't been on for a while; this is a pretty interesting and challenging job - might write up some "generic" things one day. Presently, the issue is the level of compaction of alluvium (0 to 700 mm). The 3 m dia water replacement method for determining density takes a bit of time. Cheers