INTELLIGENT WORK FORUMS
FOR ENGINEERING PROFESSIONALS

Log In

Come Join Us!

Are you an
Engineering professional?
Join Eng-Tips Forums!
  • Talk With Other Members
  • Be Notified Of Responses
    To Your Posts
  • Keyword Search
  • One-Click Access To Your
    Favorite Forums
  • Automated Signatures
    On Your Posts
  • Best Of All, It's Free!

*Eng-Tips's functionality depends on members receiving e-mail. By joining you are opting in to receive e-mail.

Posting Guidelines

Promoting, selling, recruiting, coursework and thesis posting is forbidden.

Jobs

Compaction test

Compaction test

(OP)
What are the specifications required in the soil, which will be determine using the standard or modified Proctor?

RE: Compaction test

A standard Proctor is usually used on soils with a high fines content.

RE: Compaction test

2
Another criteria is "structural fill" such as beneath footings or heavily loaded floor slabs where I would use Modified Proctor (granular soils) - most highway subgrade and fills is standard Proctor until you reach pavement structure - subbase and base where Modified is typically used - tells the Contractor you are "really" serious.

RE: Compaction test

is proctor test only applied on fill material ? or may it applied on natural ground too ?
i mean it do usually comparison between field density and lab density for natural ground to check the compacted .

RE: Compaction test

If you employ any compaction, whether natural ground or fill material, you must have a means of comparison, so a laboratory moisture-density relationship (Proctor) is necessary for each different material to be compacted.

RE: Compaction test

I've never been one to specify a compaction for natural ground - only that the natural ground be "undisturbed" (footings, etc.) For parking areas and roads we would proofroll the natural ground to locate any soft spots; if found they would be subexcavated and then backfilled. Supposedly, if the natural ground is the material on which the designer designed, he was satisfied that the natural ground was suitable for his purposes; hence, undisturbed / proofrolled. I have seen specs and known others that differ, though.

RE: Compaction test

many specs call out to scarify and recompact the cut or stripped subgrade surface. this would be done to the compaction criteria specified. i typically disregard this and only proofroll the subgrade and correct as needed (as is also usually specified). one could perform compaction testing on recompacted cut, but i don't see the benefit except achieving some sort of bureaucratic pursuit.

RE: Compaction test

Per Big H's comments, I have had a density tests done on natural ground from which material will be taken for a compacted structural fill, generally a clay. The purpose is to be able to justify a percent compaction of the fill equal or better than what exists naturally in "acceptable' conditions. This first came about when we were raising hell with a contractor not getting the specified compaction of a silty clay fill. Contractor asked our tech to "test" the natural ground where we had OK'd the use of footings. That was a surprise to us and made sense I guess. Since then I have used this "check" from time to time. Most of those checks of "suitable ground" showed percentage of lab Modified Proctor as low as 83 percent and still acceptable for footings at maybe 3,000 psf and for sure many a parking lot.. After that, I have leaned more to using the unconfined compression test as the deciding testing acceptance when compaction specs are difficult to meet. We also later learned that 95 percent of the lab density might result is a density which, later results in a significant problem with expansion of some clays. That 90 or 95 percent number is not a magic solution to getting a good job. It can be the cause of great difficulty if not used wisely.

Red Flag This Post

Please let us know here why this post is inappropriate. Reasons such as off-topic, duplicates, flames, illegal, vulgar, or students posting their homework.

Red Flag Submitted

Thank you for helping keep Eng-Tips Forums free from inappropriate posts.
The Eng-Tips staff will check this out and take appropriate action.

Reply To This Thread

Posting in the Eng-Tips forums is a member-only feature.

Click Here to join Eng-Tips and talk with other members!


Resources


Close Box

Join Eng-Tips® Today!

Join your peers on the Internet's largest technical engineering professional community.
It's easy to join and it's free.

Here's Why Members Love Eng-Tips Forums:

Register now while it's still free!

Already a member? Close this window and log in.

Join Us             Close