Replacing density survey with plate load test

[killswitchengage]

Hello
In order to increase the speed efficiency of our project , our client suggested we compact the soil with lifts of 60 cm and test it directly with PLT rather than compacting lifts of 30 cm and testing it with the SDG or Troxler.
Our contract talks about 95% OPM minimum density required , but i am thinking of using his idea provided we correlate the coefficient of compaction K from PLT with dry density in situ than continuing on with the correlation achieved ?
thank you

 

[oldestguy]

Try thicker layers for compacting. I once tested sand being compacted with vibrating rollers and thick layers. For a 4 ft. backfill compacted only on top, the compaction passed the full depth. With out testing you won't know if thicker layers work. By the way who takes responsibility if the plate load tests fail? Who correlates that small plate test to a full sized footing for being suitable? I'd be very conservative.

 

[killswitchengage]

This is the project that i shared with you on another subject, its mainly a MSE with no projected vehicles over the top of the fill. I know that PLT area of effect can extend to 2 times its diameter so a 300 mm plate can do the trick.

 

[oldestguy]

How you gonna justify a failure of the MSE job if you don't follow the specs Our contract talks about 95% OPM minimum density required ,

I'd ask the boss if he(she) will stand behind such a change when it comes to court some day. So the fabric doesn't affect the load test???? Someone is dreaming.

 

[killswitchengage]

Your feedback is more than appreciated

 

[Okiryu]

Are nuclear gages available in your area? You can use them along with cone tests for verification.

 

[Ron]

Plate load tests and density tests are done for two different reasons. You can correlate the two in your specific soil by running in-place density tests below the plate load test after running the PLT

 

[BigH]

Ron - wouldn't it be the other way round?? If you do the plate load test first, you will be increasing the density of the soil - i.e., the load of the plate would decrease the voids ratio. Do the density first to determine the density at the time of compaction and then find out what the correlated "strength" is . . .

 

[Ron]

BigH....you are correct! That's what I get for doing things "on the fly"!

We generally do an in-place density before and after the PLT.

 

[killswitchengage]

Yea i was thinking like that . Normally for a perfectly homogeneous material like mine a correlation should be possible