Investigation on Correlation Between DCP, CBR and Cyclic Triaxial tests

Experimental research was concluded to the fact that resilient modulus is the best parameter to illustrate structural strength of unbound pavement materials. Resilient modulus was used to be determined by expensive and complex cyclic triaxial test and obtained by dividing the deviator stress by pure elastic strain. Thus use of simple tests that do not require complex equipment and are performed by site technicians, has been used as an appropriate alternative in these years. One of the methods for determining the strength properties of pavement layers used in recent years is DCP test. This device is simple and inexpensive and evaluates the structural strength of unbound pavement layers in a relatively short period of time. This method is rarely used in Iran and there is no enough knowledge about it. In this research, the DCP device and test methods have been introduced.The CBR and cyclic triaxial test were performed along DCP and the correlation between the results were presented. Thus all three tests were conducted on 15 subgrade samples and after analysis it was concluded that there is a good correlation between results, especially those of DCP and resilient modulus.