Our CPT cones are equipped for:

Cone penetration depths are limited by bedrock or thick gravel layers but can push through almost any other material, even asphalt surfaces. Refusal (when the operator has reached the limits of our equipment) can occur when there is excessive flex in the rods or sharp movements of the inclinometer when the cone is pushed to the side by large gravel or cobbles. Rod flex depends on the soil, where well-consolidated material provides extra support to push through harder layers. Similar to pushing a straw too hard into your iced latte, our rods can snap under too much force.

For more information on soil behavior type classification using CPT: Robertson, 2016

Soil Behavior Types from Robertson et. al., 1986 based on CPT resistance, pore pressure, and the ratio of tip and sleeve resistance. SBT classification numbers increase with grain size; SBT zone 3 behaves like clay, while SBT zone 10 corresponds to sandy gravel.