Plate load testing is a ground bearing analysis used to assess the strength and compactness of soils. Used mainly during earthworks to validate the compaction of successive soil layers. Plate load testing is also used to ensure that stone mats are sufficiently rigid to support heavy plant such as piling rigs and cranes.

The test involves loading a circular steel plate using an item of plant as counter weight, and measuring the deflection using digital dial gauges fixed to datum bars. The ground is considered acceptable at a suitable level of settlement for the applied load.

where a yield or point of inflection is observed on the settlement versus load graph this can be taken as the failure point and can be used to determine the ultimate bearing strength of the soil. It is possible to calculate a CBR value from plate load test data, however caution should be exercised as the tests load the ground in different ways and  unexpectedly low values may be obtained on slightly softer soils.