AASHTO T 206-22

This test method describes the procedure, generally known as the standard penetration test (SPT), for driving a split-barrel sampler to obtain a representative soil sample for identification purposes, and measure the resistance of the soil to penetration of the standard sampler.

ASTM D4633 is necessary to measure the drill rod energy of a given drop hammer system, and using the measured drill rod energy, N-values can be corrected to a standard energy level.

Test results and identification information are used in subsurface exploration for a wide range of applications such as geotechnical, geologic, geoenvironmental, or geohydrological explorations. When detailed lithology is required for geohydrological investigations, use of continuous sampling methods is recommended.

Penetration resistance testing is typically performed at 1.5 m (5 ft) depth intervals or when a significant change of materials is observed during drilling, unless otherwise specified.

Note—ASTM D6066 can be used when testing loose sands below the water table for liquefaction studies or when a higher level of care is required when drilling these soils. This practice provides information on drilling methods, equipment variables, energy corrections, and blow-count normalization.