ASDSO Dam Safety Toolbox

National Engineering Handbook: Chapter 4 - Engineering Classification of Rock Materials

From ASDSO Dam Safety Toolbox
Jump to: navigation, search

Natural Resources Conservation Service, 2012

Rock material properties are measurable or describable lithologic properties of rock material that can be evaluated in hand specimens or tested in the laboratory. Rock material properties are related to the physical properties of the rock-forming minerals and the type of mineral bonding. Properties are determined from hand specimens, core sections, drill cuttings, outcrop-pings, and disturbed samples using qualitative procedures, simple classification tests, or laboratory tests. The results are applicable to hand specimens and representative samples of intact rock material. They do not account for the influence of discontinuities or boundary conditions of the rock. Typical classification elements include:

  • principal rock type
  • mineralogy (estimate percentage of principal and accessory minerals; note type of cement and presence of alterable minerals)
  • primary porosity (free draining or not)
  • hardness and unconfined compressive strength categories unit weight (dry)
  • unit weight (dry)
  • color
  • discrete rock particle size (use D50 or cube root of the product of its three dimensions)

Document Download:

2012 (current)

Errata/Special Notes:


Revision ID: 5882
Revision Date: 12/16/2022