Plate Load Test

Plate Load Test

The plate load test (see Figure 1 and 2) can be used to measure the modulus of subgrade reaction for in situ material. The test involves pressing a steel bearing plate into the surface to be measured with a hydraulic jack. The resulting surface deflection is read from dial micrometers near the plate edge and the modulus of subgrade reaction is determined by the following equation:

Figure 1. Plate load test schematic


Figure 2. Plate load test


The 1993 AASHTO Guide offers the following relationship between k-values from a plate bearing test and resilient modulus (MR):

Standard Test Methods

  • AASHTO T 222 and ASTM D 1196: Nonrepetitive Static Plate Load for Soils and Flexible Pavement Components, for Use in Evaluation and Design of Airport and Highway Pavements