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Rock Quality Designation (RQD)                                                                                                    Field Testing


                                                                                                                                                  Field Works     Description/     Limitation                              Photos
                        The RQD is a modified                                                                                                                     Purpose
                         core recovery


                        Measure of the degree of                                                                                                 3.               to obtain     not reliable
                         fractures, joints, and                                                                                                   Mackintosh       the bearing    for deep
                         discontinuities of rock                                                                                                  Probe (MP)       capacity       foundation
                         mass                                                                                                                     or               indication     and critical
                                                                                                                                                  JKR Probe        by no. of      areas.
                                                                                                                                                                   blows per
                         RQD = sum of pieces >                                                                                                                    300mm          does not
                         100 mm divided by total                                                                                                                                  give soil
                         core run                                                                                                                                                 description

                                                                                Table 4 : Rock Quality Description
                                                                                                                                                                                  unable to
                                                                                                                                                                                  penetrate
                                                                                 RQD (%)         Description of rock                                                              hard stratum
                                                                                                      quality                                                                     or gravel

                                                                                                                                                                                  bed
                                                                                   0 - 25            Very Poor
                                                                                                                                                                                  max depth
                                                                                  25 – 50              Poor
                                                                                                                                                                                  15.0m
                                                                                  50 – 75               Fair


                                                                                  75 – 90              Good

                                                                                  90 - 100           Excellent


                                                                                                                                                                                                  Figure 7: Mackintosh Probe (MP) and MP Logs
                                         Figure 6: Rock Quality Designation

       12  PUBLIC WORKS DEPARTMENT MALAYSIA                                                                                                                                                                                      GEOTECHNICAL ENGINEERING HANDBOOK  13
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