Response to Information Request - Received on 19/04/2012 · OPW11/0335

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Notes on Description and Classification of Soil


                                                      DESCRIPTIVE TERMS FOR MATERIAL PROPORTIONS


                               Co.arse Grained Soils                                                             Fine Grained Soils

         % Fines                             Modifier                             % Coarse                                   Modifier

            <5        Omit, or use ’trace’                                            <   15      Omi~ or use trace.
           5-12       Describe as ’with clay/silt’ as applicable.                    15-30        Descnbe as ’with sand/gravel’-as applicable.
            >12       Prefix soil as ’silty/clayey’ as applicable                     > 30        Prefix soil as ’sandy/gravelly’ as applicable.




                                                               STRENGTH TERMS         -
                                                                                          COHESIVE SOILS


                   Strength             Undrained Shear                                         Field Guide to. Strength

                   Term                      Strength
                   Very 50ft                 <   12 kPa           Exudes between the fingers when squeezed in hand.

                   Soft                   12-25 kPa               Can be moulded by light finger pressure.

                   Firm                   25- 50 kPa              Can be moulded by strong finger pressure.

                   Stiff                  50     -
                                                     100 kPa      Cannot be moulded by fingers, can be indented by thumb.

                   Very stiff            100     -
                                                     200 kPa      Can be indented by thumb nail.

                   Hard                      >   200 kPa          Can be indented with difficulty by thumb nail.




                                                               DENSITY TERMS    -    NON COHESIVE SOILS


                                             Density                     Density           SPT "N"          CPTCo.ne
                                             Term                         Index                             Resistance

                                             Very loose                   <   15 %             0-5          0-2 MPa

                                             Loose                      15-35%                 5-10          2-5 MPa

                                             Medium dense               35-65%              10 -30          5 -15 MPa

                                             Dense                      65-65%             30-50           15- 25 MPa

                                             Very dense                   >85%                 >50           >   25 MPa




COLOUR


The colour of a soil will generally be described in a ’moist’ condition using simple colour terms (eg. black, grey, red, brown etc.) modified as necessary by
’pale’,’dark’,’light’ or ’moWed’. Borderline colours will be described as a combination of colours (eg.grey.brown).


EXAMPLE


eg: CLAYEY SAND (SC) medium dense, grey-brown, fine to. medium grained with sill.
                           -




Indicates a medium dense, grey.brown, fine to medium grained clayey sand with sill.




Notes on Description and Classification 01 Soil
Revision 2, November 2001                                                                                                                              Page 2 012