Rock strength parameters from classification and testing - Geotechnical Investigation and Design Tables - page 74

Table 6.12 Variation of rock strength (Walthman, 1994).
Uniaxial compressive Strength Rock classification

strength (MPa)

Sedimentary Metamorphic Igneous

10 Lowest Salt, Chalk

20 Shale, Coal, Gypsum,

Triassic sandstone,
Jurassic limestone

⏐

40 Mudstone

60 Carboniferous sandstone Schist

80 Slate

100 Carboniferous limestone Marble

150 Greywackes Gneiss

200 Granite

250 Highest Hornfels Basalt

Table 6.13 Relative rock strength combining above variations.
Uniaxial compressive

Strength Rock classification

strength (MPa)

Sedimentary Metamorphic Igneous

10 Lowest Salt, Chalk Welded tuff

20 Shale, Coal, Gypsum, (2) Porphyry,

⏐

Triassic sandstone, Jurassic Granadiorite

limestone

40 Mudstone, Sandstone, Phyllites

Clay - Shale

60 Carboniferous sandstone, (2) Schist, Granadiorite

Limestone, (2) Dolomite, Micaschists

Siltstones

80 Slate, Granite,

Quartzite Rhyolite

Serpentinite

100 (2) Carboniferous limestone, (2) Marble, Granite,

Dolomite, Siltstone, (2) Schist Pegmatites

Sandstone Quartzites

150 Greywackes Gneiss (2) Granite,

Granadiorite,
Rhyolite

200 Quartzite Granite, Diorite

250 Highest Hornfels Basalt

6.14 Parameters from rock type
•

The table below uses the above considerations, by combining intact rock strengths
with, rock type, structure and weathering.