WHY HAVE SOME OF MY CBR TESTS TAKEN LONGER THAN NORMAL TO COME BACK?
In early 2017 a change was made to the Australian Standard when undertaking CBR testing. From then on the curing times for some soils when undertaking CBR testing was extended to reflect the difference between the Field Moisture Content (FMC) of a soil and its Optimum Moisture Content (OMC).
The changes to the Australian Standard mean that depending upon the FMC to OMC difference and the Liquid Limit (LL) of the sample, the time that the sample needs to be cured (basically leaving the sample in sample bags to allow the MC to reach equilibrium) has increased up to 7 days.
This time is on top of the required 4-day soak that the vast majority of all CBR’s are subject to.
This change only really affects cohesive materials (the curing time for sands and gravels is hours not days).
Please don’t hesitate to contact Soil Surveys should you have any queries in relation to this article or general soil/rock/water testing services.
Posted on Linkedin 24th August, 2018