Clegg Impact Test as Alternative to CBR
•(1) Dr Clegg’s Revised General Correlation of 1986 for a 4.5 kg Clegg Impact
•  Soil Tester (to ~700 % CBR), roughly 1/4 of the CIV plus 1, then squaring:-
•                                             2
•% CBR = [(0.24 × CIV) + 1]                                          “r” = 0.957
•
•The equation above was derived from results obtained in Australia, New Zealand and the UK. These tests cover a wide range of soils for both laboratory and in-situ testing, unsoaked, non-surcharge conditions.
•
•(2)  Dublin Light Rail Project Correlation for 2.25 kg Clegg Impact Soil Tester
•   for testing in-situ material prior to construction (to ~50 % CBR):-
•
•                   [(Gm (3rd Drop Result) – 14.936) / 79.523]
•% CBR = e                                                                  “R” Squared = 0.9317
•
•The equation above was derived by engineers working on the Dublin LRT Project, Civil, Track & Building Works C600, Contractor: MVMBNI JV in the period October 2001 to January 2003.  “Gm” represents “gravity units” peak deceleration upon impact rather than the “tens of gravities units” scale of CIV.