A ratio used in determining the bearing capacity of a foundation;
defined as the ratio of the force per unit area required to penetrate a soil mass with a 3 sq
in. (19.4 sq cm) circular piston at the rate of 0.05 in. (1.27 mm) per min to the force required for corresponding penetration of a standard crushed-rock base material; usually determined at a penetration of 0.1 in. (2.54 mm).