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!
  • Students Click Here

*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

Related Articles


CBR % from Clegg Readings

CBR % from Clegg Readings

CBR % from Clegg Readings

I have a set of clegg impact values (CIV) which i have obtained and recorded and I need to convert them to %CBR Values.
I have used the following formula on each CIV that i have recorded and have the results from them.

% CBR = 0.07(IVxIV)

An example of a result I am getting are as follows:- 0.07(59 x 59) = 243.67

Does this mean that the CBR % is 243.67%? or am I wrong?

I have some Design Specifications that require CBR Value of 30% but all my results are throwing out HIGH readings after the equation so its throwing me alittle.

Can anyone help?


RE: CBR % from Clegg Readings

It would be interesting to know the types of soil/road base (etc) you are dealing with. I've never used the CIH but there are different weights . . . Are you sure your Clegg Impact number is 59 and, perhaps, not 5.9?? Clegg's chart doesn't go that high from what I can see. Also, as with many correlations, one should try to get a correlation for their particular site (i.e., site specific) or area.

Just wondering if you ever did a google search?
http://web1.cnre.vt.edu/forestry/cofe/documents/20... (see page 3)

RE: CBR % from Clegg Readings

Basically i have undertaken clegg readings at 20m intervals along an old existing stone farm track which I intend on laying tarmac on.
the ground is stone and compacted like concrete and so the readings which i have are high. these readings are correct as there are no decimal places in the readout screen. Clegg hammer used is : 4.5kg CIST/882 CLEGG IMPACT SOIL TESTER.

RE: CBR % from Clegg Readings

Then the CBR is meaningless.

Anyway to prove that there are no "soft spots" in the "track" - I would presume that it wasn't an engineered pavement structure so you might get variations from place to place.

You might have better luck doing a Benkelman Beam study - it will tell you the deflections at the test locations along the track - which would tell you how much additional pavement structure is needed. (I chose the BB since it is likely more readily available than a falling weight deflectometer).

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!


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