Down to Earth

I was recently asked whether there is such a thing as the perfect in-situ soil test, probably in response to a presentation that I had given a few weeks earlier, in which I enthusiastically described the advantages of CPT. The answer is obviously no: there is no single test that provides the most reliable information on the various soil parameters for all soil types. Having said that, CPT is generally speaking a very appropriate testing method in soils other than rock and gravel, providing good data on a very wide range of soil parameters. As such it is clearly the most versatile in situ soil test available. What is even more important, especially here in North America, is that CPT provides information on more soil parameters than SPT in all soil conditions other than gravel. Moreover, for those soil parameters that can be derived from both the SPT and the CPT results, CPT provides generally more accurate results and the results are available within minutes after the test was done (before the test equipment leaves the test site). In other words, CPT is a very useful test to provide an all-around characterization of the soil in a very short period of time. Not perfect, but in my opinion by far the best in the class of in-situ soil tests.