Determination of optimum moisture content of a clay using nonlinear ultrasonic technique

The determination of optimum moisture content is very important for soil materials. Conventionally the optimum moisture content is estimated by the measurement of void ratio (or dry density) of soil samples, which is sometimes time-consuming and tedious. This paper proposes a nondestructive evaluation (NDE) technique based on the nonlinear ultrasonic theory to determine the optimum moisture content of clay. It is found the nonlinear parameter of material defined by the nonlinear ultrasonic technique presents a similar variation trend with the void ratio of clay, corresponding to the increased moisture content. The same optimum moisture content is found by observing the variation of nonlinear parameter and void ratio. The results indicate the developed nonlinear ultrasonic technique could be a fast and convenient testing method for the determination of optimum moisture content of soil materials.