Aggregate -1

Rock Type Hardness, Toughness Resistance to Stripping1,2 Surface Texture Crushed Shape
Igneous
Granite Fair Fair Fair Fair
Syenite Good Fair Fair Fair
Diorite Good Fair Fair Good
Basalt (trap rock) Good Good Good Good
Diabase (trap rock) Good Good Good Good
Gabbro (trap rock) Good Good Good Good
Sedimentary
Limestone Poor Good Good Fair
Sandstone Fair Good Good Good
Chert Good Fair Poor Good
Shale Poor Poor Fair Fair
Metamorphic
Gneiss Fair Fair Good Good
Schist Fair Fair Good Fair
Slate Good Fair Fair Fair
Quartzite Good Fair Good Good
Marble Poor Good Fair Fair
Serpentine Good Fair Fair Fair
Notes:

  • Aggregates that are hydrophilic (water-loving) tend to strip more readily since water more easily replaces the asphalt film over each particle.

  • Freshly crushed aggregates with many broken ionic bonds tend to strip more easily.