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AASHTO T90 – Standard Method of Test for Determining the Plastic Limit and Plasticity Index of Soils


The plastic limit of a soil is the lowest moisture content at which the soil remains plastic. The plasticity index of a soil is the range in moisture content, expressed as a percentage of the mass of the oven-dried soil, within which the material is in a plastic state. The plasticity index is calculated as the numerical difference between the liquid limit and plastic limit of the soil.


plastic limit; plasticity index; soil

AASHTO T90 Accredited Laboratory

Applied Testing & Geosciences, LLC is accredited for performing tests using the AASHTO T90 standard.

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