The Application of PFWD in Sub-Grade Compactness Test

Controlling compactness can increase sub-grade capability of resisting deformation and improve the pavement structure strength and stiffness. Portable Falling Weight Deflector (PFWD) has many advantages than the traditional method of testing sub-grade strength. The paper introduces the PFWD technical indexes and researches the PFWD performance in the sub-grade test. The paper research relations between deflector by PFWD test and compactness on the four sub-grade type, include low liquid limit clay soil and difference proportion cement stabilized soil. The result proves the better linearity relativity between deflector by PFWD test and compactness, The correlation formula between the back-calculate modulus and compactness is educed. Sub-grade compactness can be effectively controlled by PFWD rapid test. The paper provides the new test method and foundation for rapidly and objectively testing compactness. It is practical and theoretical significance for enriching the actual guide regulation.