Rock samples Hardness (hand sample) Rebound hardness
Surface texture and lamination
Dry density kN/m3
Slake durability index (%)
Slightly weathered Sandstone (BP2g, BP2s) Moderately weathered Sandstone (BP3) BP4 Highly weathered Sandstone (BP5) Slightly weathered shale ( S2 ) Moderately to Highly weathered shale S5 S5a Very hard and intact Hard and slightly disintegrate Breakable and easily disintegrate Easily broken and disintegrate Hard and slake Breakable and easily slake Breakable and slake > 30
5-30
10-15
dented
< 20
10-20
dented
Smooth and intact Slightly massive and gritty Partially massive and gritty Very gritty and massive Soapy and intact Powdery and slightly massive Powdery, gritty and massive 2.4 – 2.6 2.2 – 2.7 2.0 – 2.7 1.5 – 1.9 2.4 – 2.5 2.2 – 2.4 2.5 – 2.6 98 94 - 46 92 96 92