Contact US

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.

Students Click Here

ASTM D422 Hydrometer Test vs Sieve Analysis

ASTM D422 Hydrometer Test vs Sieve Analysis

ASTM D422 Hydrometer Test vs Sieve Analysis

Hello all,

I'm working on a hydrometer test for our small company, but we just started doing these so I'm spending some time reading into the theory and analyzing our results. Technically ASTM D422 has been withdrawn; I've read some studies showing that the estimated particle sizes from the hydrometer portion of the test can be underestimated by up to two orders of magnitude due to the assumption of Stokes Law of falling spheres vs the disk or other shapes of real clay particles. This might be what we're running into but it seems unlikely because it's our first test and the distributions measured from the sieve analysis portion contradict results from the hydrometer portion. That is, the hydrometer portion is measuring all of the soil that passes the #10 sieve, which is estimated by percent suspended (calculated from specific gravity of the fluid+floating soils) and the estimated maximum particle size still in suspension (from Stokes Law). That same soil is later washed, dried, and measured again via a sieve analysis. The sieves are showing only 12% passing a #200, while the hydrometer analysis indicates 42% suspended after 2 minutes (so a particle size of about 0.037mm, about half of the .074mm of a #200 sieve).

Obviously these can't both be true, but we've triple checked the equations and they seem to be right. Is this a common problem with this test or is there something likely wrong with the calcs (spreadsheet attached)? I've double checked the measurements with this material and they are right. Also, is there a better place to ask questions about test-specific calculations than this forum? I've been looking around and can't find anything for that.


RE: ASTM D422 Hydrometer Test vs Sieve Analysis

Steven....red flag your post and repost in the soil testing engineering or geotechnical forum. You will get more activity there.

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! Already a Member? Login


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