Standard Test Method for Measuring Deflections using a Portable Impulse Plate Load Test Device

Note 1: If the load plate is in “perfectly uniform” contact with the unbound material under the plate, then deflection of the load plate should be equal to the deflection of the surface of the unbound material under test. However, with typical unbound materials a 100% uniform contact can seldom be achieved. Accordingly, the test surface shall be as clean and smooth as possible with loose granules and protruding material removed. For gravel surfaces it is recommended that a thin layer of fine sand be placed over the test point. For fine-grained materials, this will help in obtaining a reasonably uniform contact between the load plate and the surface. See 5.1 in Test Method .

Note 2: The volume of the pavement foundation materials affected by the applied load is a function of the magnitude of the load, plate size and rigidity, loading rate, buffer stiffness, and the stiffness and shear strength of the pavement foundation materials. Therefore, care must be taken when analyzing the results because the data obtained by the Portable Impulse Plate Load Test may be obtained under substantially different conditions than when a heavy moving wheel load passes over the pavement surface after construction is complete.