SOIL REPORT: The plastic limit

 SOIL REPORT: The plastic limit

Abstract:  This blog post is a report of laboratory soil analysis to find the liquid limit which is a coefficient needed for soil classification.

 

Apparatus:  We use an aluminum can, wet soil, brush, balance, and oven.

 

Objective: Determine the plastic limit

 

Procedures:

(1)  Weigh the remaining empty moisture cans with their lids, and record the respective weights and can number on the datasheet.

 

(2)  Take the remaining 1/4 of the original soil sample and add distilled water until the soil is at a consistency where it can be rolled without sticking to the hands.

 

(3)  Form the soil into an ellipsoidal mass. Roll the mass between the palm or the fingers and the glass plate. Use sufficient pressure to roll the mass into a thread of uniform diameter

 

(4)  Continue this alternate rolling, gathering together, kneading, and re-rolling until the thread crumbles under the pressure required for rolling and can no longer be rolled into a 3.2 mm diameter thread

(5)  Add soil to the can weigh the moisture can containing the soil, record its mass

(6)   Place the can into the oven. Leave the moisture can in the oven for at least 16 hours.

(7)  Repeat steps more times. Determine the water content from each trial by using the same method

 

Rolling of soil mass on a ground glass plate to determine the plastic limit.

 

Data collection and calculation (manual result):

 

Mass of can	Mass of can + wet soil	Mass of can + dry soil	Mass of wet soil	Mass of dry soil
3.97 g	9.43 g	8.34 g	5.46 g	4.37 g

 

Calculation of water content: w = (Mw) / (Ms)

Mass of water = mass of wet soil – a mass of dry soil

Water content = (5.46 – 4.37) *100 / 4.37 = 24.9427 %

W = plastic limit = 24.9427 %

 

Discussion: Because the time was limited, we make only one simple.

 

References:

1)    Soil lab (BAU)

2)    Book: principles of geotechnical engineering (25th edition)