Point Load Test

How is the Point Load Test Performed?

To determine the point load strength index of a rock, a specimen is simply subjected to an increasingly concentrated load until failure occurs. Failure occurs in this test when the rock specimen has been split. The load is applied in a concentrated manner using two coaxial, conical platens. The load at which the specimen fails can be used to calculate the point load strength index.

What Does a Point Load Test Specimen Look Like?

A typical test specimen should not be less 30 mm (1.18 in.) and no more than 85 mm (3.35 in.) in diameter. The preferred diameter for a point load test is about 50 mm (1.97 in.). The specimen typically does not require any specific preparation; however, the specimen should not have any abrupt irregularities that can generate stress concentrations.

How are Rock Characteristics Determined?

After performing the point load test, the maximum load the specimen was able to resist before failure can be found. By taking this maximum load and dividing by the equivalent core diameter squared, the uncorrected point load strength index is determined.

What are the Trade Offs of the Point Load Test?

The point load test offers two major advantages over similar tests. First, the point load test is a relatively cheap test, as the system required to perform the test is not very large or complicated. The point load test does not require specialized specimen preparation, thus eliminating the need for other expensive equipment in order to prepare a specimen.