Compaction testing report 2

[JuniorM]

The attached report shows results of compaction testing on 75 mm minus crushed rock material with 38% oversize.
The Modified Proctor value is 2270 kg/m3 at 7.7% MC. The required compaction was 95%.
Could anyone tell me if this report is legitimate based on ASTM standards.

 

[Ron]

Report is not properly linked/stored....try again. Can't pull up file

 

[JuniorM]

Here is the link to the report file

 

[Ron]

Since you didn't provide the whole test report, we cannot determine its general compliance with ASTM standards for reporting the particular results.

I suggest you get a copy of the appropriate standard (ASTM D6938) for in-place density testing of soil and soil-aggregate mixtures using the nuclear method to see if the reporting requirements have been met.

One would have to observe the testing to determine if the field test methods employed complied with ASTM requirements.

On the surface, the report looks ok from a results reporting standpoint.

 

[JuniorM]

This is the whole report. Correcting 2270 kg/m3 for 38% OS will make it over 2400 kg/m3.
Field densities are in the 2150-2200 kg/m3 range and still make 95% or higher relative compaction.

 

[Ron]

I understand your dilemma. The 38% oversize takes the material outside the strict procedure of ASTM D1557; however, you have little choice in developing a method to use for QA/QC in the field. I assume you are applying a Density Interference Coefficient to the MDD. It appears that when you apply such a factor, all of the tests fail to meet the 95% criteria.

If you can justify the coefficient, then use it. If not, document why you can't justify it and the figure out how you want to develop a maximum dry density using some other test method besides D1557, the Modified Proctor.

I would also suggest that you read two publications:

"CONTROL OF EARTH-ROCK MIXTURES: HOW TO DEVELOP AND USE DENSITY INTERFERENCE COEFFICIENTS AND OPTIMUM WATER CONTENT FACTORS"
US Army Corps of Engineers Instruction Report GL-92-1, Written by Victor H. Torrey, III.

and

"A Rapid Method of Construction Control For Embankments of Cohesive Soil" by Jack W. Hilf
US Bureau of Reclamation Engineering Monograph No. 26

 

[JuniorM]

I'm sorry for the misunderstanding. The actual density of material measured in the field was above 2300 kg/m3, then it was corrected down, according to the second option in the ASTM standard, and compared to uncorrected MPMDD.
The question is - is it allowed to submit a compaction testing report as it is shown?
Does it make any sense to have that correction down option in the ASTM standard?
In order to calculate relative compaction using this method, you have to correct down every field density test result and compare it with an uncorrected Proctor value. And you have to do all calculations by hand using a calculator in the field. Of course nobody would do it this way. A technician would enter a corrected up Proctor value, do the test, get the actual density and relative compaction form the nuclear gauge, then, in the office, correct every field density down and put in the report.

 

[Ron]

The individual field density tests should not be corrected. The Proctor value should be the only correction.

The report should not any corrections that are applied and should include both the corrected and uncorrected values.

 

[JuniorM]

Ron, ASTM 4718 at 4.2 provides two equations to correct field moisture content and field density to compare them with uncorrected Proctor density and optimum moisture content. The report is from a real life, there are hundreds of the same reports and all of them signed by a professional engineer.

 

[Ron]

JuniorM....you originally asked the question and have seemingly done enough research to answer your own question. What else is there?

This is a convoluted process. It appears that your testing laboratory has at least jumped through the ASTM hoops for correcting things. In my opinion, the only deficiency in the report, assuming all corrections have been applied properly, is that the report does not lay out all the assumptions and corrections that have been made.

My $0.02

 

[dBasement]

If the percentage of oversize varies in the field from the proctor value, it makes sense to correct the field densities. It is more labour intensive to dig up each test location and assess the percentage oversize. Most techs I know use a graph of oversize values. We also developed a quick correction list of corresponding corrected densities with each proctor. Keep in mind that if each density is corrected, each moisture content needs to be corrected as well. It looks to me like that wasn't done, which would account for the low moistures.

 

[JuniorM]

Ron, the deficiency of the report is that it doesn't show the actual field density and this is against ASTM, the reporting uses that correction option in D4718 wrongfully. Thank you for the discussion.
DBasement, you do not correct the field densities, you write them down and report them, ASTM also requires you to estimate OS rock percentage by digging up each test location - then estimate it either visually by volume or in the lab by weight.

It seems like it is not a very important issue - wrong reporting, as soon as we know that compaction is good, but it always starts with small things like that. It is clear to me that there are lots of professionals who don't understand the methodology and very often don't care.

 

[EITGeotechnical]

JuniorM, was the proctor done based on method D since it is more than 30% OS ? if yes I assume that the 2270 is with the OS, correct me if i am wrong.
I never heard of correcting down a field dry density, its always correcting the proctor dry density to count for the over size. your field value is your value unless you want to correct for the moisture content.

Its very hard to get good reading when you have more than 30% OS because of the segregation of the material and more practical solution is to use control strip instead.

 

[bb29510]

you do not correct the field density, the purpose of correcting the lab sample is so you can get it to fit in the mold, large rock will not fit the six inch mold

ICC Master Special Inspector, Structural Masonry, Reinforced Concrete, Soils, Structural Bolted Joints, Structural Welding, AWS CWI D1.1

 

[dgsarath]

To my memory 38% oversize means we can not apply the Proctor test if the oversize quantity is more than 30%. I hope my memory is correct.

 

[HSIII]

In accordance with ASTM D1557, any material with more than 30% oversize cannot be proctored using this method, as what usually happens is that the required correction factor involved would throw the maximum dry density number way outside of any type of ability to achieve 95% compaction (as is the case here with the uncorrected 2270 kg/cubic m). With that being said, maybe the correct action to take is a visual compaction approach by a licensed geotechnical engineer or licensed soils technician.

Good luck.

 

[BigH]

Actually, Section 1.4 does permit a slight additional oversize:
"1.4 If the test specimen contains more than 5 % by mass of
oversize fraction (coarse fraction) and the material will not be
included in the test, corrections must be made to the unit
weight and water content of the test specimen or to the
appropriate field in place density test specimen using Practice
D 4718."