Introduction of Fine Soil

WHAT IS FINE SOIL?

SOIL

VERY COARSE FINE
COARSE SILT CLAY

BOULDERS COBBLES GRAVEL SAND

SOIL GROUP SOIL is grouped into COARSE, VERY
COURSE and FINE based on the grain
(particle) size.

SOIL PARTICLE (GRAIN) SIZE

Imagine the powder
texture of flour (e.g.,
wheat flour, corn flour.)

Reference: BS5930: 2015 – Section 6: Description of Soil and Rock

FINE SOIL Fig. 2.1 Consistency Relationship

SILT  The classification of fine soil based on the
CLAY plasticity consistency (Consistency Limit).

 Soil consistency – soil physical state
characteristic at a given water content.

 Refer Fig. 2.1 Consistency relationship

CONSISTENCY LIMIT

SL Shrinkage Limit The water content at which drying-shrinkage at
PL Plastic Limit constant stress ceases.
LL Liquid Limit
The water content at which the soil discontinue to
be plastic and becomes a semi-plastic solid.

The water content at which the soil discontinue to
be liquid and become plastic.

CONSISTENCY LIMIT

SL Shrinkage Limit The water content at which drying-shrinkage at constant stress
PL Plastic Limit ceases.
LL Liquid Limit
The water content at which the soil discontinue to be plastic and
becomes a semi-plastic solid.

The water content at which the soil discontinue to be liquid and
become plastic.

 The most important are
LL and PL – represent
plastic states

 LL – upper bound Plastic
 PL - lower bound range

 The range of plastic
state  Plasticity Index

(PI)

 PI = LL – PL

CONSISTENCY LIMIT

INFO

LL and PL are
determined from
the LABORATORY

TESTS.

% LL Degree of Plasticity
< 35 Low plasticity
35 - 50
50 - 70 Intermediate plasticity
70 - 90 High plasticity
> 90
Very high plasticity
Extremely high plasticity

- NORAIDA MOHD SAIM -
[email protected]