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

Permeability of Sand-Clay Mixtures

Permeability of Sand-Clay Mixtures

Permeability of Sand-Clay Mixtures

Hello everyone,

I had a really important problem and performed an extensive literature search, however, I couldn't find anything except few articles.

My problem is: Sand's permeability.

We all -I think- sand settles almost immediately due to high permeability. Howewever, in a project, I had a chance to get UD from clayey sands and oedometer test yields very low permeabilities although sand ratio is around 75% and clay is around 15-20%.

When I looked it up, I found an article that performed consolidation tests on different sand-clay ratios. I saw that even 10% clay ratio is decreasing permeability to 10-8 m/s.

What experience do you have on this issue? Do you have any resource? I really don't want to say there is a time-dependent settlement in sands, however, it seems like that. I would like to discuss this issue and waiting any contribution from you guys.


RE: Permeability of Sand-Clay Mixtures

there are correlations based on D10 and D20. It does't take much reduction in D20 or D10 to change the permeability.


ípapß gordo ainÆt no madre flaca!

RE: Permeability of Sand-Clay Mixtures

Your experience:
"very low permeabilities although sand ratio is around 75% and clay is around 15-20%."
is very common and to be expected.

In my experience, landfill cover construction, it doesn't take much clay to really lower the permeability of the mix. However, get your clay content much higher and you run into the problem of shrinkage and the resu8lting cracks make for significant infiltration potential.

Here was a funny experience. Years ago the early on Wisconsin DNR management engineers were going to show me (a consulting engineer) one of their pride landfills where they required a high clay percentage in the cover. It was a 1.5 hour trip each way. The landfill had been closed for three years. It was summer time. As we walked out on the landfill, in the tall grass I noticed cracks in the cover and shoved a folding rule down about three feet into the solid waste via these many open cracks. On the way to the site they "preached" to me as to what it takes to "do a good job". Needless to say, on the way home, they were totally silent. However, they turned out to be great friends and referred landfill prospects to me for advice.

RE: Permeability of Sand-Clay Mixtures

I remember from soil mechanics class many moons ago the professor mentioning that as little as 15% clay content can choke off the sand's permeability.


RE: Permeability of Sand-Clay Mixtures

The Northwest Florida ERP Manual has a graph showing hydraulic conductivity vs fines content. I think UF students may have developed the graph based on hundreds of permeability tests run on Florida sands with varying fines contents. May be worth a look.

RE: Permeability of Sand-Clay Mixtures


Yes, for example Hazen formula considers D10 and yields for 0.0013mm=D10, approximately 1.7 x 10-8 m/sec yields. Very low..


I didn't know, thank you for these cases.


Your professor is definetely right. Nice term: choking.


Great resource! I found the document you told which is "REFERENCES AND DESIGN AIDS FOR ENVIRONMENTAL RESOURCE PERMIT APPLICANT’S HANDBOOK VOLUME II", Figure 1-12 shows the graph you mentioned.
Thank you very much. Is it published in a paper?

RE: Permeability of Sand-Clay Mixtures

In my experience with SP and SP-SC materials, at about 10 to 15 percent clay content, the unit weight jumps up significantly in laboratory compaction and the permeability drops by one to two orders of magnitude...from 10^-3 to 10^-5 cm/s. Keep in mind that clay particles are significantly smaller than sand particles and will easily fill those interstitial voids in sand.

RE: Permeability of Sand-Clay Mixtures

permeability can also vary by two or three orders of magnitude depending on the compaction moisture content. Refer to Mitchel, Hooper and Campenella (sp) where they show permeability of one soil all compacted to the same relative compaction, but showing variation by 3 orders of magnitude depending on whether the compaction was below the line of optimums or above. Much lower permeability when wet of the line of optimums!

Hazen is one of the correlations, but there are others.


ípapß gordo ainÆt no madre flaca!

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


White Paper - Strategies to Secure Connected Cars with Firewalls
White-hat hackers have demonstrated gaining remote access to dashboard functions and transmissions of connected vehicles. That makes a firewall a vital component of a multilayered approach to vehicle security as well as overall vehicle safety and reliability. Learn strategies to secure with firewalls. Download Now
White Paper - Model Based Engineering for Wire Harness Manufacturing
As complexity rises, current harness manufacturing methods are struggling to keep pace due to manual data exchanges and the inability to capture tribal knowledge. A model-based wire harness manufacturing engineering flow automates data exchange and captures tribal knowledge through design rules to help harness manufacturers improve harness quality and boost efficiency. Download Now
White Paper - What is Generative Design and Why Do You Need It?
Engineers are being asked to produce more sophisticated designs under a perfect storm of complexity, cost, and change management pressures. Generative design empowers automotive design teams to navigate this storm by employing automation, data re-use and synchronization, and framing design in the context of a full vehicle platform. Download Now
eBook - Simulation-Driven Design with SOLIDWORKS
Simulation-driven design can reduce the time and cost of product development. In this engineering.com eBook, we’ll explore how SOLIDWORKS users can access simulation-driven design through the SOLIDWORKS Simulation suite of analysis tools. Download Now

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