Standard Method of Test for
Determining the Plastic Limit and Plasticity
Index of Soils
AASHTO Designation: T 90-00 (2004)
1.1.The plastic limit of a soil is the lowest water content determined in accordance with the following 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.
1.2. 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.
1.3.The Hand Rolling Method shall be the referee procedure.
Click below to downloadAASHTO Designation: T 90-00 (2004) pdf free
Click here to download AASHTO Designation: T 89-02 (2006) pdf free download