×
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!
  • 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

Jobs

Bank Weight of Soil Same as Max. Dry Density
3

Bank Weight of Soil Same as Max. Dry Density

Bank Weight of Soil Same as Max. Dry Density

(OP)
If soils report states that Maximum Dry Density of Sandy Silt is 121.5 lbs/cu ft, would this also represent the Bank, or Natural State Weight?  The soils report has no shrink/swell percentages, and I am trying to arrive at some reasonable adjustment factors.  Any help would be appreciated.

RE: Bank Weight of Soil Same as Max. Dry Density

Hi,
If I understand your query right; it is difficult to make an approximation of the natural density from the maximum dry density test results. (if someone has seen one please let me have a copy, would be interesting).

To evaluate the natural density, you definitely need to obtain some cores or do sand replacement tests at site. These are very cheap tests and can be conducted easily.

Having said this, 121.5 pounds per cubic feet is approx 19.5 kN/m3; this is not much for a maximum dry density; which can be up to 21 or so for a well graded material. For all approximations, you could assume a natural density of 17 kN/m3. I presume it is an embankment and generally could be clayey silts. Any case, you must state you density assumption clearly (you have to save your back).

Cheers



RE: Bank Weight of Soil Same as Max. Dry Density

jafcon1...you need to provide a bit more context for your "maximum dry density" statement.  This term is usually associated with a laboratory test to determine such for field comparison to in-place density after compaction.  If they are using the term to imply bank density, then you should ask the Geotech to clarify.

Get the terms clarified as I have seen lawsuits over such.  The 121 value may or may not be high, depending on the nature of the material.  Densities can vary all over the board....90 pcf to 130pcf or more.

RE: Bank Weight of Soil Same as Max. Dry Density

(OP)
Perhaps I aked my question in the wrong way.  What I'm trying to determine is if it is reasonable to use the Geo Lab's Max Dry Density Weight as Loose Weight Estimates for trucking?  Or am I way out in left field?   

RE: Bank Weight of Soil Same as Max. Dry Density

Not only in left field, but in foul territory.  I might estimate that the loaded truck is 85% of MDD standard - typically, when you dump sand it is in this round figure. Ashjun - our silty sand here has a MDD modified of only 1.55 to 1.6g/cc. We are below the specified "minimum" MDD value but we've passed it for use - why pass up a good sand for embankment construction just to use a heavier clay with PI of 40?

RE: Bank Weight of Soil Same as Max. Dry Density

Jafcon1...BigH is right.   Now you are in litigation territory.  85% is a reasonable estimate of bank density to maximum dry density; however, it is very easy to determine the in-place density of a material, excavate a small amount and determine its density again after the "bulking" associated with excavation.  If you are moving a lot of soil, a small error in these estimates can cost a lot of money in the transportation/placement/compaction of the materials.  

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