AASHTO T 90-20 PDF Format



AASHTO T 90-20 PDF Format


Standard Method of Test for Determining the Plastic Limit and Plasticity Index of Soils
standard by American Association of State and Highway Transportation Officials, 2020



The plastic limit of a soil is the lowest water content determined in accordance with this procedure at which the soil remains plastic. The plasticity index of a soil is the range in water content, expressed as a percentage of the mass of the oven-dried soil, within which the material is in a plastic state. It is the numerical difference between the liquid limit and plastic limit of the soil.

The following applies to all specified limits in this standard: For the purpose of determining conformance with these specifications, an observed value or a calculated value shall be rounded off “to the nearest unit” in the last right-hand place of figures used in expressing the limiting value, in accordance with ASTM E 29.

Two procedures for rolling out soil samples are provided in this method: the Hand Rolling Method and the Plastic Limit Device Method. The Hand Rolling Method shall be used as the referee procedure.

AASHTO T 90-20 is often conducted in conjunction with T 89, which is used to determine the liquid limit of soils.

Product Details

Number of Pages:
File Size:
1 file , 1.2 MB
Product Code(s):
T090-20-UL, T090-20-UL, T090-20-UL