# Plasticity: Plasticity Functions In geotech: Geotechnical Engineering

## Description

These functions compute diferent aspects related to plasticity:

• `LL` calculates and plots a soil's liquid limit (LL) using the flow curve from measured lab data.

• `PI` calculates plasticity index.

• `LI` calculates liquidity index.

• `A.line` calculates the PI corresponding to the A-line on Casagrande's plasticity chart.

• `plasticity.plot` plots a soil's plasticity parameters on Casagrande's plasticity chart.

## Usage

 ```1 2 3 4 5``` ```LL(N, w, draw) PI(LL, PL) LI(w, LL, PL) A.line(LL) plasticity.plot(LL, PL = NA, PI = NA) ```

## Arguments

 `LL` Liquid Limit (percent) `PL` Plastic Limit (percent) `PI` Plasticity index (percent) `w` moisture content (percent) [see details below] `N` vector of number of blows obtained from the liquid limit test (for LL function) `draw` logical variable: TRUE if plot of flow curve is desired, and FALSE to suppress the creation of the plot (for LL function)

## Details

• Note that all inputs should be entered as percents, not decimals (e.g. w = 23, not w = 0.23)

• The argument w (water content) should be a single value for the LI function that represents the soil's in-situ moisture content; and w should be a vector of values for the LL function that represent the measured water contents, each with N blows.

• For plot.plasticity and A.line, either PL or PI must be specified in addition to LL.

## Value

• `LL` outputs a soil's liquid limit and, optionally, a plot of the soil's flow curve.

• `PI` outputs a two-element list composed of:

1. PI = Plasticity index (percent)

2. descr = qualitative description of soil based on Sowers (1979)

• `LI` outputs a two-element list composed of:

1. LI = Liquidity index (percent)

2. descr = qualitative description of soil based on Sowers (1979)

• `A.line` outputs the plasticity index corresponding to the A-line on Casagrande's plasticity chart

• `plasticity.plot` is used to make a plot of a soil's plasticity parameters (LL and PI) on Casagrande's plasticity chart. No numerical values are output from this function.

## Author(s)

James Kaklamanos <[email protected]> and Kyle Elmy <[email protected]>

## References

Casagrande, A.M. (1948). "Classification and Identification of Soils", ASCE Transactions, Vol. 113, pp. 901-991.

Sowers, G.F. (1979). "Introductory Soil Mechanics and Foundations: Geotechnical Engineering", 4th edition, Macmillan, New York.

`USCS`, `AASHTO`, `grainSize`
 ``` 1 2 3 4 5 6 7 8 9 10 11``` ```## Example code for Plasticity Index PI(LL = 80, PL = 30) ## Example code for Liquidity Index LI(w = 55, PL = 20, LL = 50) ## Example code for plasticity plot plasticity.plot(LL = 40, PL = 20) ## Example code for liquid limit analysis LL(N = c(72, 37, 14), w = c(7, 15, 21), draw = TRUE) ```