Proctor correction

[killswitchengage]

Hello
I used a French method in order to take into account the oversized aggregates greater than 20 mm . The material is a composed of gravel and sand 0/40 mm . The calculated modified proctor dry density is 2.14 t/m³ and after the correction the dry density is 2.45 t/m³. My question is the corrected value reasonable ?

 

[hokie66]

I don't think so. That density is about the same as concrete, not a compacted soil material.

 

[Okiryu]

For the base and subbase course material that we use for pavements here (GW material) we normally see max. dry densities from modified proctor on the order of 2.2 -2.3 metric tons/m3. These materials have around 9% fines and 50% gravels (particles greater than 4.75 mm). What is your USCS classification?

 

[BigH]

Your correction has to do with oversize particles, eh? Did you use the larger mould when you did the test? You might want top check out the following:

http://www.ibuildroads.com/questions/oversize-correction-for-proctor-test-results/

(one of the responders has been involved with this for over 35 years.

@Okiryu - you need to be aware of the specific gravity of the materials you are dealing with. In Ontario, our typical modified Proctor maximum dry density is/was typically in the order of 136+/- pcf. When I moved to Vancouver, the values were in the order of 143 to 145 pcf. Different materials - different specific gravities.

 

[Okiryu]

BigH, thanks for the advise. I am assuming that your advise relates to verify that values do not exceed the zero air void line. Fortunately, here in Japan, base and subbase are standardized materials, so they are very consistent. Gs in the order of 2.7.

 

[Okiryu]

BigH, I just read the link you sent about proctor correction. Our base and base materials have around 30% to 20% retained in the 3/4" sieve which according to that link, in this case, field density tests are not recommended. I normally see sand cone tests close to 100% modified proctor for this type of materials, so I am not sure about the concern for conducting field density tests for materials that have more than 30% retained in the 3/4" sieve...

 

[killswitchengage]

Thank you all
Well the material is used as a base layer. 26% is the amount of oversize particles bigger than 22 mm or 3/4" i believe . i was just lost at the corrected value which seemed very unreasonable , so i asked this question.

Now i want to express another point : the subbase or natural soil under the sandy gravel is composed of silty sand , so if i compact the sandy gravel upon it , will it be correct to assume that most of the water will be drained because of the silty sand ? cuz i found maximum density for half the optimum water content !