Highways England earthworks specifications often call for testing to monitor the compaction level of placed materials. As this is the 'gold standard' specification, many other earthworks contracts call for the same type of testing, The basic principle is to first determine the maximum dry density that the material can achieve in laboratory conditions.  

 

Depending on the material and the likely compaction methods on-site, this can be tested in various ways and we can advise on which would suit best. Once this laboratory maximum dry density has been determined then site based density tests on compacted material can be undertaken with the on-site density values compared to the maximum laboratory value in terms of percentage.  

 

A common specification requirement would be that the on-site density should be at least 95% of the laboratory maximum density. In summary compaction monitoring would comprise of laboratory maximum density tests and on-site density tests.