Consistency (bottom)

Cohesive soils such as clay can be assessed for consistency.

In soil science, consistency is the nature of cohesive ( fine-grained ) soils depending on the water content . The consistency is an important criterion for the compactability of the soil. ${\ displaystyle w}$

In the case of non-cohesive (coarse-grained) soils, one does not speak of consistency, here the storage density provides information about the properties of the soil.

In building materials science , one speaks of consistency as a measure of the softness of the building material soil. The softness of fresh concrete is also referred to as consistency (see concrete consistency ).

Areas and limits of consistency

According to Atterberg, a distinction is usually made between four consistency ranges, which cover all the instantaneous states of fine soils occurring in nature , and three consistency limits in between (also Atterberg's limits or state limits according to Atterberg ), each representing a limit water content:

solid (dry soil)
- Shrinkage limit ( shrinking limit w _S )
semi-solid
- Plastic limit ( plastic limit w _P )
plastic (stiff, soft, pulpy = easily deformable bottom)
- Flow limit ( liquid limit w _L )
liquid (viscous).

The consistency limits are defined in DIN 18122 and can be determined by laboratory tests.

Key figures

{\ displaystyle {\ text {Consistency number}} I_ {c} = {\ frac {w_ {L} -w} {w_ {L} -w_ {P}}}}

With

the natural water content w
Plasticity number . ${\ displaystyle I_ {p} = w_ {L} -w_ {P}}$

Activity count ${\ displaystyle I_ {A}}$	Description of the soil
> 1.25	active sound
0.75 .. 1.25	normal tone
<0.75	inactive sound

To the activity of clay minerals to describe that can activity numbers are used. It describes the ratio of the plasticity index to the mass fraction of the grain size less than or equal to 0.002 mm (cohesive soil): ${\ displaystyle I_ {A}}$