Cone Penetration Test (CPT)

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Definition - What does Cone Penetration Test (CPT) mean?

A cone penetration test refers to the in-situ testing of soil via one of two methods utilizing cones to measure resistance and depth.

The two types of cone penetration tests are static cone penetration and dynamic cone penetration tests. They are indirect exploration methods that are used for geotechnical site investigation and are simple, quick, and physical in nature, making them environmentally friendly and cheap.

The dynamic and static cone penetration test methods give a measure of the in-situ resistance of soil to penetration. This method can help determine the strength of in-situ soil as well as the depth and thickness of sub-surface soil layers.

Trenchlesspedia explains Cone Penetration Test (CPT)

The static cone penetration test is best performed in soft clay, silt, medium, and fine sands. The test is performed by pushing the standard cone with a base area of 10 cm2 and an angle of 60 degrees, into the soil at a rate of 10 to 20 mm/sec.

After installation, a sounding rod is pushed into the soil at a steady rate of 10 mm/sec in order to advance the cone, and readings are noted in the gauge at regular depth intervals.

The dynamic cone penetration test is performed by driving a cone into the ground by repeated blows with a standard weight dropped from a standard height. The penetration of the cone is measured after every blow and recorded. For harder soil, the reading may be noted after a certain number of hammer blows.

The standard cone size is 20 mm diameter and angle of 60 degrees, with the hammer weighing 8 kg.

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