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Compaction not meeting specs

Compaction not meeting specs

Compaction not meeting specs

Trying to perform compaction for a gas commpressor site. Proctor is 145 4.3 -2% +3% . Running with a 2 1/4- that really looks like a 3- to me. Material is running very dry 3.0-3.8. running with a 9" lift with vibratory roller and getting a occational compaction, with 2 hours compaction. How do I get compaction consistitcy with less roll time, or is a pad foot roller an option. Product is also boney, with the gradations on there high limits. Ready to pull my hair out!!!

RE: Compaction not meeting specs

Is water being added to bring the material closer to or above OMC?

Are you certain that the oversize correction was done properly on the Proctor? With this gradation of stone, very little of the actual material was used in the performing the Proctor and a significnat amount of the Proctor value is oversize correction.

You also don't indicate if this is a modified or standard Proctor or what the required percent compaction is.

How is the material behaving during compaction?

Mike Lambert

RE: Compaction not meeting specs

without knowing many details, the primary way to compact better and faster is to adjust water content to optimum and apply sufficient compactive energy. sounds like adding water and getting a heavier compactor might help. plate compactors are not generally adequate or appropriate for large areas. make sure the lab proctor is appropriate for the actual material being compacted. double check the field tests. make the lifts thinner. screen out the oversize material

RE: Compaction not meeting specs

Is the material angular?... a padfoot roller (sheepsfoot?) is not recommended for granular material... With large aggregate, a heavier roller may be in order as cvg noted.


RE: Compaction not meeting specs

I'd like to see the Proctor curve. I'd like to know whether they did a Method A, B, or C Proctor. I'd like to see the grain-size distribution curve. I'd like to see the percent oversize found in the lab. I'd like to know if the percent oversize in the field is equivalent.

It seems like this is a rather open-graded aggregate. Such aggregate should be governed by a relative density spec rather than a relative compaction spec. I just can't believe you got a proctor on an open-graded aggregate unless (as already mentioed) most of the oversize material was removed.

For open-graded aggregate, I'd just use a method spec - you know, 2-ft lift, 10T vibratory, so many passes and BAM, it's good!

Just out of curiosity. . . What are you building and what's the consequence of failure if the actual placement is 5 percent under the specification requirement? Sometimes it helps to put things into perspective. . .


¡papá gordo ain’t no madre flaca!

RE: Compaction not meeting specs

Is there any chance the material you are compacting is breaking down to smaller sizes to a denser mix in the mold? Seems like a pretty high number if it is "boney". If the Proctor is on a changed material not representing the job itself, blame the lab test.

Try to find a container suitable for all of the material, since stone corrections sometimes are way off, especially if more than 40% stone. Then, compact the stuff in that container with the same energy per cubic foot that is applied in the Proctor mold. That would be your Proctor as long as you don't break down gradation to a different gradation even there.

Are you using a nuclear density testing device? If so, is is calibrated for the material you are compacting? Your problem may be that form of field density test. You may have to devise a different form of field density test, such as a small test pit lined with thin plastic and filled with a material of given density, such as water. If the water to the material when compacting doesn't help the density, your testing is likely wrong.

I loved to come on these jobs of a competitor. After the testing was found wrong, I got a new client.

RE: Compaction not meeting specs

All the above are valid considerations. With a material unit weight as high as this material, you have fewer options to affect the compaction. I would look critically at the following, in order:

1. Make sure the moisture content in place is above optimum by about 1-1/2 to 2 percent. Compact as the material is drying back toward optimum.
2. Be sure that the Proctor was run correctly and with appropriate top size compensation.
3. If the material is friable, pay attention to what OldestGuy noted...the material can be breaking down during compaction, which renders the test inaccurate.
4. Make sure that the density test method matches the material. Some materials cannot be accurately tested with nuclear density gages; particularly the moisture content. Validate with direct volumetric comparison (sand cone density).

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