Experimental study for development of correlation between CBR and Dynamic Cone Penetration Tests

Abstract

CBR (California bearing ratio), gives realistic results which aids the desig n process of new flexib le pavements as well as the restoration of existing pavements all over the world. The conventional CBR test procedure has always been time consuming, relatively expensive and has generally low repeatability. The repeatability has bee n found extremely low when it comes to sensitive soils like Lacustrine soils, locally known as Kerawa soils in No rth India. All these hindrances indicate that the p resent study should be carried out using Dynamic Cone Penetrometer (DCP). The DCP has been widely used to evaluate the in-situ strength of undisturbed soil and compacted sub-grade materials. The present study aims at developing a correlation of DCP t est values with the CBR test values for Lacustrine (sedimentary upland) soil format ions so that a quick assessment of road sub-grades can be made. Analysis of experimental data indicated that there is a very good relat ionship of the measured soil strength (i. e., unsoaked Californ ia Bearing value and Dynamic cone penetration values) with the soil in itia l state factor as described by the combination of in itial dry density, water content and void ratio. Co mparison of measured and predicted values of soaked CBR a nd DCP using the developed equation clearly indicate the valid ity.