Casagrande plasticity chart (LL vs PI)

Create the Casagrande plasticity chart plotting Liquid Limit (LL) vs Plasticity Index (PI). The plot shows the A-line and U-line, a polygon representing typical classification zones, and labels for standard regions used in soil plasticity interpretation.

Usage

Casagrande_chart(ll.max = 110, pi.max = 90, lang = "en")

Arguments

ll.max

numeric. Maximum value for the liquid limit (LL) axis (x-axis). Default 110.

pi.max

numeric. Maximum value for the plasticity index (PI) axis (y-axis). Default 90.

lang

character. Label language; 'es' for Spanish or 'en' for English. Default 'en'.

Value

A ggplot2 object (class 'gg' and 'ggplot').

Details

The function computes the A-line and U-line values for LL vs PI and draws a polygon approximating the CL-ML zone. It returns a ggplot2 object so the caller can further customize the plot (titles, themes, annotations) or save it.

References

Holtz, R. D., Kovacs, W. D. & Sheahan, T. C. (2011). An Introduction to Geotechnical Engineering. Prentice Hall.

See also

Other classification plots, soil mechanics: clay_activity(), soil_collapse(), soil_expansion(), soil_swelling(), ternary_shepard(), ternary_usda()

Examples

Casagrande_chart()
#> Warning: Removed 42 rows containing missing values or values outside the scale range
#> (`geom_line()`).

Casagrande_chart(ll.max = 80, pi.max = 60) + ggplot2::ggtitle('Casagrande chart')
#> Warning: Removed 42 rows containing missing values or values outside the scale range
#> (`geom_line()`).

soil_df = data.frame(ll = c(67, 58, 77, 51),
                     pi = c(39, 19, 22, 20),
                     sample = paste0('M', 1:4))
Casagrande_chart(lang = 'es') +
ggplot2::geom_point(ggplot2::aes(ll, pi, shape = sample, color = sample), soil_df, size = 3) +
ggplot2::scale_shape_manual(values = 1:4)
#> Warning: Removed 42 rows containing missing values or values outside the scale range
#> (`geom_line()`).