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Calculating AS 1289.3.9.1 Cone Liquid Limit test

Calculating AS 1289.3.9.1 Cone Liquid Limit test

Calculating AS 1289.3.9.1 Cone Liquid Limit test

(OP)
Just a quick question on the calculation of the cone liquid limit test.  In the past we have been using natural log on a computer program, NATA has come back saying this i wrong. I have adjusted the program to use Log base 10 but still need a bit of help with the full caculating of the test.  Can someone out there please in laymans terms describe how to calculate it on paper and if possible on a excel spreadsheet- I am no scientist and have no idea about log or anything like that just starting to learn it.

Thanks in advance

RE: Calculating AS 1289.3.9.1 Cone Liquid Limit test

Hi BioBloke,

Sounds like NATA (along with many people in the industry) are getting this confused.

The standard requires the points to be plotted on a chart with linear scale for moisture contents and log base 10 scale for the number of blows. It then specifies to draw a straight line of best fit through the data. Alternatively, through Note 12, it allows you to calculate to that line of best fit.

To calculate a straight line of best fit on a semi log chart you need to use log natural, with the equation y=(c*LN(x))-b .  

If you were to use a linear equation, y=m*x-b, through the data,  it would plot as a curve and thus not be compliant with the requirement to draw a straight line.

To see how to plot this on an Excel chart, take a look at this website

http://spreadsheetpage.com/index.php/tip/chart_trendline_formulas/

If you need any help getting it going, post back here.

HTH
Michael

RE: Calculating AS 1289.3.9.1 Cone Liquid Limit test

There is a typo with both those equations. They should be
y=(c*LN(x))+b
and
y=m*x+b

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