Evaluation of PFWD and DCP as Quality Control Tools for Sub-Grade of GW and SW Soils

The Stiffness modulus is one of the necessary inputs in mechanistic-empirical pavement design and Quality Assurance/ Quality Control ( A C Q Q ) of pavement layers construction. The use of Portable Falling Weight Deflectometer (PFWD) for measuring the stiffness modulus of unbound pavement layers is increasing worldwide. The modulus can also be indirectly calculated by the results of other available devices. The Dynamic Cone Penetrometer (DCP) is an easy-to-access device for evaluating the strength of unbound pavement layers in a cheap, easy and fast way. In this study, the stiffness modulus of PFWD and penetration rate of DCP was correlated for the sub-grades ranging from well-graded sand (SW), which is highly consisted of SiO2 and Al2O3, and well-graded gravel (GW) classification. In addition, the results indicated that a good correlation exists between PFWD moduli and DCP results and also for the precise evaluation of the SW soil modulus with a considerable amount of SiO2 and Al2O3, a coefficient factor, of C = 2.39 , was presented.