Approved Plan - EXE230029

            Classification of Material Weathering
              Term                                             Abbreviation           Definition

                                                                                      Material is weathered to such an extent that it has soil properties. Mass
              Residual Soil                                            RS             structure and material texture and fabric of original rock are no longer visible,
                                                                                      but the soil has not been significantly transported.

                                                                                      Material is weathered to such an extent that it has soil properties. Mass
              Extremely Weathered                                      XW
                                                                                      structure and material texture and fabric of original rock are still visible.
                                                                                      The whole of the rock material is discoloured, usually by iron staining or
                                                                                      bleaching to the extent that the colour of the original rock is not recognisable.
              Highly Weathered                                 HW                     Rock strength is significantly changed by weathering. Some primary minerals
                                              Distinctly                              have weathered to clay minerals. Porosity may be increased by leaching, or
                                             Weathered                      DW        may be decreased due to deposition of weathering products in pores.
                                              (Note 1)
                                                                                      The whole of the rock material is discoloured, usually by iron staining or
              Moderately Weathered                            MW                      bleaching to the extent that the colour of the original rock is not recognisable,
                                                                                      but shows little or no change of strength from fresh rock.
                                                                                      Rock is partially discoloured with staining or bleaching along joints but shows
              Slightly Weathered                                       SW
                                                                                      little or no change of strength from fresh rock.

              Fresh                                                    FR             Rock shows no sign of decomposition of individual minerals or colour changes.

            NOTE 1: The term ‘Distinctly Weathered’ is used where it is not practicable to distinguish between ‘Highly Weathered’ and ‘Moderately Weathered’ rock.
            ‘Distinctly Weathered’ is defined as follows: ‘Rock strength usually changed by weathering. The rock may be highly discoloured, usually by iron staining.
            Porosity may be increased by leaching, or may be decreased due to deposition of weathering products in pores’. There is some change in rock strength.




            Rock Material Strength Classification
                                                                                                                Guide to Strength

                                                          Uniaxial              Point Load
                                                       Compressive            Strength Index
              Term                 Abbreviation       Strength (MPa)            Is(50) (MPa)        Field Assessment

              Very Low                  VL                 0.6 to 2              0.03 to 0.1        Material crumbles under firm blows with sharp end of pick;
              Strength                                                                              can be peeled with knife; too hard to cut a triaxial sample by
                                                                                                    hand. Pieces up to 30mm thick can be broken by finger
                                                                                                    pressure.

              Low Strength               L                  2 to 6               0.1 to 0.3         Easily scored with a knife; indentations 1mm to 3mm show
                                                                                                    in the specimen with firm blows of the pick point; has dull
                                                                                                    sound under hammer. A piece of core 150mm long by 50mm
                                                                                                    diameter may be broken by hand. Sharp edges of core may
                                                                                                    be friable and break during handling.
              Medium                    M                   6 to 20               0.3 to 1          Scored with a knife; a piece of core 150mm long by 50mm
              Strength                                                                              diameter can be broken by hand with difficulty.

              High Strength              H                 20 to 60                1 to 3           A piece of core 150mm long by 50mm diameter cannot be
                                                                                                    broken by hand but can be broken by a pick with a single
                                                                                                    firm blow; rock rings under hammer.

              Very High                 VH                 60 to 200              3 to 10           Hand specimen breaks with pick after more than one blow;
              Strength                                                                              rock rings under hammer.
              Extremely                 EH                  > 200                     > 10          Specimen requires many blows with geological pick to break
              High Strength                                                                         through intact material; rock rings under hammer.




            February 2019                                                        10



Document Set ID: 22532435
Version: 1, Version Date: 07/08/2023