Plasticity Chart For Soil Mechanics

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SILT (M-SOIL), M, plots below A-line m and C may be combined as FINE SOIL, F. CLAY, C, plots above A-line I

SILT (M-SOIL), M, plots below A-line m and C may be combined as FINE SOIL, F. CLAY, C, plots above A-line I

Plasticity Chart Components
Liquid limit (percent) Fig. 1.7 Plasticity chart for the BSCS (after BS5930: 1981).

The main soil types are designated by capital letters:

G Gravel M Silt, M-soil

S Sand C Clay

F Fine soil, Fines Pt Peat

The classification 'F' is intended for use when there is difficulty in determining whether a soil is a silt or a clay.

Originally all soils that plotted below the A-line of the plasticity charts were classified as silts. The term 'M-soil' has been introduced to classify soils that plot below the A-line but have particle size distributions not wholly in the range of silt sizes.

Behind the letter designating the main soil type additional letters are added to further describe the soil and to denote its grading and plasticity. These letters are:

W Well graded L Low plasticity (wL<35%) P Poorly graded I Intermediate (35<wL<70) Pu Uniform H High plasticity (50 < wL < 70)

O Organic E Extremely high (wL>90%)

The letter O is applied at the end of the group symbol for a soil, no matter what type, if the soil has a significant amount of organic matter within it. Examples of the use of the symbols are set out below.

Soil description

Group symbol

Well graded silty SAND

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  • Carl Curran
    How to draw aline chart in soil mechanics?
    2 years ago
  • brogan
    How to draw a plasticity chart?
    12 months ago
  • Sarah
    What can i make for soil mechanics chart?
    10 months ago
  • Joshua
    What is A line diagram in soil mechanics?
    8 months ago
  • Wegahta
    How to draw plasticity graph?
    5 months ago
  • Siiri
    How will you classify organic from plasticity chart?
    4 months ago
  • priamus
    What type of soil that is plot above the plasicity?
    23 days ago
  • helvi suorsa
    What type of soil that plot above a line in the plasticity chart?
    21 days ago

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