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Failed compaction test

J

jhark123

Well-Known Member
Joined
Feb 1, 2015
Messages
45
Location
Washington
Hi all, I’ve never failed a compaction test before but I guess there’s a first time for everything. We had a spot repair job with a bunch of locations and the compaction results are coming back at around 90%. They are mostly ductile iron pipe installs about 4 to 5 feet deep. I’m not sure where it went sideways if we didn’t use enough water or too much bedding rock or too big of lifts. It was 5/8 chip for bedding and 5/8 minus for backfill mostly tight areas in the road compacted with a jumping jack. I am thinking of running around with a vibratory plate mounted on a 5 ton mini. Will compacting from the surface do anything or am I going to need to take out material. Opinions are appreciated!
 
O

oarwhat

Senior Member
Joined
Dec 14, 2009
Messages
840
Location
buffalo,n.y.
We had one job where the owner hired his own dirt guy. I don't really know his title. We had done dozens of jobs with different dirt guys and compaction companies. Never any big issues.
Well day one this guy tells me how everyone else is doing it wrong. He used a higher compaction percentage and some different style fabric. Fabric was okay but twice as expensive. Meeting his compaction numbers was all but impossible. Never had to work with him again thank god.
 
CM1995

CM1995

Administrator
Joined
Jan 21, 2007
Messages
13,377
Location
Alabama
Occupation
Running what I brung and taking what I win
X2 on check the proctor.

Did you run anything heavy over the surface of the fill to see what it looked like? More than once we've had fill that a loaded 85K tri-axle rolled solidly over that was still testing in the 80-90% range which was obviously wrong. Every time the proctor was incorrect. Seems to happen more now a days, I guess it's just the quality of workmanship in the lab.
 
Last edited:
mowingman

mowingman

Senior Member
Joined
Jul 10, 2010
Messages
1,237
Location
SE Ohio
Occupation
Retired
I started my career as a soils engineer and did thousands of soil proctors and soil compaction tests for 10 years. The soil proctor is not usually wrong, but, it could be, or they could have done the test with a different material than what you used. However, most of the time, the real problem is the moisture content. If you can dig down a foot and take some soil moisture tests, then compare them to what the proctor test used.
 
CM1995

CM1995

Administrator
Joined
Jan 21, 2007
Messages
13,377
Location
Alabama
Occupation
Running what I brung and taking what I win
Agree with MM on a material difference. I am assuming the material you used is a quarry product? If so did the testing agency do their own proctor or go off the quarry’s?
 
skyking1

skyking1

Senior Member
Joined
Nov 3, 2020
Messages
7,664
Location
washington
soil squeeze will usually complain if you have it over optimum moisture, but most good materials go in better a little on the wet side and let it dry back. Bad, sensitive soils are another matter. Don't give the rookie the garden hose! It may never dry back :D
 
C

claris

New Member
Joined
Oct 4, 2023
Messages
2
Location
Florida
mowingman said:
I started my career as a soils engineer and did thousands of soil proctors and soil compaction tests for 10 years. The soil proctor is not usually wrong, but, it could be, or they could have done the test with a different material than what you used. However, most of the time, the real problem is the moisture content. If you can dig down a foot and take some soil moisture tests, then compare them to what the proctor test used.
Click to expand...
Hello Mr. @mowingman, I am building a house in South Florida and we are ready to order the compaction test, but in past 2 weeks we got heavy rains every day. My question is heavy rains will impact on the compaction test results? How long should I wait? Thank you,
 
mowingman

mowingman

Senior Member
Joined
Jul 10, 2010
Messages
1,237
Location
SE Ohio
Occupation
Retired
If the soil proctor is done the correct way, then it will tell you what the optimum moisture level is for the correctly compacted soil. During the initial proctor test, the soil is dried out at the lab, then compacted at increasing levels of moisture until the max compaction weight is reached. That weight, at that specific level of moisture is then the standard you use when you put in the fill and test it for compaction. (I hope this explanation is clear). So, it really does not matter how wet the soil is, when collected, when you do the initial test in the lab. you dry the soil and screen it first. The max weight will be obtained at the optimum moisture, no matter how it starts out.
In the field, if you are putting in the fill too wet, or if it is not fully compacted and absorbs more water, then your test will fail to meet the standard set in the lab. If, in the field, the fill was properly placed and compacted at the proper moisture level, then it could rain on it a foot, and make no difference in how the field compaction compares to the lab standard. Of course, before testing, you would need to skim off the wet layer on top, maybe an inch or two, then do your field compaction test. I hope this is clear, as it has been almost 45 years since I did all that testing.
You can read up on how a soil proctor test is done in the ASTM manual. Just look up "ASTM soil proctor test". I think it is spec: D698, but not sure.
 
C

claris

New Member
Joined
Oct 4, 2023
Messages
2
Location
Florida
mowingman said:
If the soil proctor is done the correct way, then it will tell you what the optimum moisture level is for the correctly compacted soil. During the initial proctor test, the soil is dried out at the lab, then compacted at increasing levels of moisture until the max compaction weight is reached. That weight, at that specific level of moisture is then the standard you use when you put in the fill and test it for compaction. (I hope this explanation is clear). So, it really does not matter how wet the soil is, when collected, when you do the initial test in the lab. you dry the soil and screen it first. The max weight will be obtained at the optimum moisture, no matter how it starts out.
In the field, if you are putting in the fill too wet, or if it is not fully compacted and absorbs more water, then your test will fail to meet the standard set in the lab. If, in the field, the fill was properly placed and compacted at the proper moisture level, then it could rain on it a foot, and make no difference in how the field compaction compares to the lab standard. Of course, before testing, you would need to skim off the wet layer on top, maybe an inch or two, then do your field compaction test. I hope this is clear, as it has been almost 45 years since I did all that testing.
You can read up on how a soil proctor test is done in the ASTM manual. Just look up "ASTM soil proctor test". I think it is spec: D698, but not sure.
Click to expand...
Thank you so much for your time and answer. It it pretty clear now. :)
 
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