Validity of Atterberg Limit charts that has been used in Geotechnical Engineering
Validity of Atterberg Limit charts that has been used in Geotechnical Engineering
(OP)
Dear all,
I have been working for a small geotechnical firm in the US. I am responsible for writing geo-reports and sending it to the client. While I have bee writing report, I found something weird about taking PI of the soil that I never done in my life.
My boss wants to do only Liquid limits test and used the liquid limit obtained from laboratory to the table of default list of liquid limit, and plastic limit. He finally wants to use the Plasticity index obtained on this way for the further calculation.
I had checked with several research papers and thesis where they had done both Liquid limits and plastic limit tests and compared the value obtained from actual test to the value obtained from that table. These values are off by significant margin (sometimes >6). I don't know whether the way taking value of Plastic limits from table based on liquid limits is right or wrong?
Does any of your company use same chart as attached?
Thanks in advance.
I have been working for a small geotechnical firm in the US. I am responsible for writing geo-reports and sending it to the client. While I have bee writing report, I found something weird about taking PI of the soil that I never done in my life.
My boss wants to do only Liquid limits test and used the liquid limit obtained from laboratory to the table of default list of liquid limit, and plastic limit. He finally wants to use the Plasticity index obtained on this way for the further calculation.
I had checked with several research papers and thesis where they had done both Liquid limits and plastic limit tests and compared the value obtained from actual test to the value obtained from that table. These values are off by significant margin (sometimes >6). I don't know whether the way taking value of Plastic limits from table based on liquid limits is right or wrong?
Does any of your company use same chart as attached?
Thanks in advance.





RE: Validity of Atterberg Limit charts that has been used in Geotechnical Engineering
RE: Validity of Atterberg Limit charts that has been used in Geotechnical Engineering
RE: Validity of Atterberg Limit charts that has been used in Geotechnical Engineering
The plastic limit is more difficult to get right and is less repeatable than the liquid limit; however, it still needs to be run.
RE: Validity of Atterberg Limit charts that has been used in Geotechnical Engineering
Feng, T. W. (2000). Fall-cone penetration and water content relationship of clays. Geotechnique, 50, 181-187.
I don't think this has really been picked up in practice, but in a discussion by Prof Mesri & Peck of a different method, they suggest that the Feng method may be reasonable.
O'kelly, B. C., Mesri, G. & Peck, R. B. (2011). A new method of measuring plastic limit of fine materials. Geotechnique, 61, 88-92.
RE: Validity of Atterberg Limit charts that has been used in Geotechnical Engineering
RE: Validity of Atterberg Limit charts that has been used in Geotechnical Engineering
f-d
¡papá gordo ain’t no madre flaca!
RE: Validity of Atterberg Limit charts that has been used in Geotechnical Engineering
Roll out a couple of plastic limits on your own time, and see how well your boss' correlation really is.
You are cheating your clients if you tell them you are performing the limits tests in accordance with ASTM standards. If not, how much does the PI really govern the recommendations you are making, and how much of the recommendations are based on local experience?