Pocket Penetrometer
The pocket penetrometer test is useful for estimating consistency and approximate measurements of unconfined compressive strength. It yields approximate information which is not suitable for foundation design. However, comparison of pocket penetrometer measurements at the time of sampling on the field and in the laboratory prior to laboratory strength testing may be useful for comparing consistency. Perform pocket penetrometer testing and record values on any and all cohesive or fine-grain samples collected from Thin-Walled /(Shelby) tube sampling and adhere to the following guidance:
- Take more than one (1) reading on a sample and average values.
- Cut off any observed fall-in or cuttings that were mixed in with the sample.
- Use firm, slow, and constant push on flat, flush surfaces cut perpendicular to the sample length.
- Keep in mind that the pocket penetrometer is at best a crude instrument. Soil around the tip or spring mechanisms may influence readings as would age of the spring. Comparison testing on almost identically dense clay material (side by side pushes) should result in a deviation of readings of no more than quarter ton.