# Plasticity: Plasticity Functions

## 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

LL(N, w, draw)
PI(LL, PL)
LI(w, LL, PL)
A.line(LL)
plasticity.plot(LL, PL = NA, PI = NA)

## Arguments

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)

## 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:
- PI = Plasticity index (percent)
- descr = qualitative description of soil based on
Sowers (1979)

`LI`

outputs a two-element list composed of:
- LI = Liquidity index (percent)
- 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.

## 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.

## 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.

## Examples

## 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)