<p><p><strong>References:<br></strong><em>SHRP 2-Phase I Technology Assessment</em></p><p><strong>Method Summary</strong></p><p>The Cone Penetration Test (CPT) is a field method to indirectly measure the strength of the soil. In this test a small diameter cone is pushed into the ground at a constant rate. The point resistance and the friction on the sleeve above the cone are measured with depth either electronically or mechanically (not typically used anymore). While this test is unable to retrieve samples, it provides a continuous soil profile. The measured values can be used to estimate soil classification and strength parameters. CPTs are not always feasible for evaluation of SCPs. The ability to push a cone into the soil is a function of material type, density, depth, and push capability. Guidance for CPT feasibility can be found in FHWA Report FHWA-SA-91-043, <em>The Cone Penetrometer Test.</em></p><p><strong>Accuracy and Precision</strong></p><p>Generally regarded as a more reliable test than the SPT in applicable soils.</p><p><strong>Adequacy of Coverage</strong></p><p>The frequency of CPT tests is based on size of construction, number of machines in operation, subsurface variability, and importance of the structure being built.</p><p><strong>Implementation Requirements </strong></p><p>CPT testing is a common procedure. However, the test requires experience to push the cone and interpret the results.</p><p><strong>General Comments</strong></p><p>Commonly, construction specifications will mandate a resistance value or interpreted soil property value for the SCPs and/or for the in-situ soil for sites with cohesionless or cohesive soils. Barksdale (1987) states that if low permeability layers are present in the soil, the CPT cone resistance values should be taken as long after construction as possible due to temporary loss of strength caused by disturbance and remolding of soil surrounding the SCP. The required CPT values will vary depending on the project. The CPT values are an indicator of the ability of the soil foundation to support the service loads and prevent liquefaction. CPT cone resistance values can be correlated to produce relative density values and Cyclic Resistance Ratio (CRR).</p></p>