Standard Method of Test for Determining the Plastic Limit and
Plasticity Index of Soils
Standard Method of Test for Determining the Plastic Limit and Plasticity
Index of Soils
AASHTO
AASHTO
Designation: T 90-16
Technical
Section: 1a, Soil and Unbound Recycled
Material
Release:
Group 3 (OCTOBER)
7. CALCULATIONS
7.1 The plastic limit of the soil is the
moisture content determined in Section 6.7,
expressed as a percentage of the oven-dry mass, and determined in accordance
with T 265. Report the plastic limit to the nearest whole number.
7.2 If applicable, calculate the
plasticity index of a soil as the difference between its liquid limit and its
plastic limit, as follows:
Plasticity index= liquid limit –
plastic limit
7.3 Report the result as calculated in Section 7.2, as the plasticity index, except under the following
condition:
7.3.1
When the liquid limit or plastic limit cannot be determined, report the
plastic index as NP (non plastic)
7.3.2 When the liquid limit is equal to, or
greater than, the liquid limit, report the plasticity index as NP.
Calculation attach with graph in below
figure
8. PRECISION STATEMENT
8.1 This precision statement applies to
soil with a plastic limit range between 15 and 32, tested using the hand
rolling method.
8.2 Repeatability (Single Operator)
--- Two result obtained by the same operator on the same sample in the same
laboratory using the same apparatus should be considered suspect if they differ
by more than 10 percent of their mean.
8.3 Reproducibility (Multilaboratory)
--- Two result obtained by the different laboratories should be considered
suspect if they differ from each other by more than 18 percent of their mean.
