The use  of new presses to carry out the CBR test (California Bearing Ratio) in Switzerland has shown that, for materials with a high CBR coefficient and identical compaction energy, the shape and dimensions of the hammer have a definite influence on the results obtained.

In addition, for these materials having a high CBR coefficient, the deformation of the dynamometric ring of the old (but still often used) CBR presses, which modifies slightly the penetration speed of the punch, also influences the results obtained significantly.

The research should clarify these different influences, notable through the use of systematic tests and a critical and comparative examination of foreign standards recognised internationally (ASTM, BSI, AFNOR, DIN).

Swiss standards on the subject need to be modified as a function of the research results.