Hydraulic Structures: Fourth Edition

Table 2.5 Characteristics of core soilsSoil description

Cracking resistance

Erosion–piping

Optimum compaction

Sensitivity to

(BS 5930)

resistance

roller

compaction watercontent control

Very silty sands or

Low; increases with



d

Low; increases with



d

Pneumatic tyred

High to avoid brittleness

gravels; 6% clay

and



Ip

and



Ip

(20–80 t)

(GM–SM)Very clayey sands or

Intermediate at

Intermediate

Pneumatic tyred

Low to control

uw

gravels; 20% clay

representative

d

(20–80 t)

(GC–SC)Low-plasticity clays (CL)

Relatively flexible

High; increase with



d

Pneumatic tyred or

Intermediate to high to

sheepsfoot

control

uw

High-plasticity clays

Flexible; can resist large

High; increase with



d

Sheepsfoot

High to control

uw

(CH)

deformations