PLASTIC LIMIT TEST

NEED AND SCOPE  

        Soil is used for making bricks, tiles, soil cement blocks in addition to its use as foundation for structures.

APPARATUS REQUIRED

1.    Porcelain dish.

2.    Squeeze Bottle and Spatula

3.    Balance of capacity 200gm and sensitive to 0.01gm

4.    Ground glass plate for rolling the specimen.

5.    Containers to determine the moisture content.

6.    Oven thermostatically controlled with interior of non-corroding material to maintain the temperature
around 105⁰ and 110⁰C.

PROCEDURE

1.        Put 20 gm of air-dried soil, passed thorough 425 mm sieve (In accordance with I.S. 2720: part-1), into an evaporating dish. Add distilled water into the soil and mix it thoroughly to form uniform paste (the soil paste should be plastic enough to be easily molded with fingers.)

2.        Prepare several ellipsoidal shaped soil masses by squeezing the soil between your fingures. Take one of the soil masses and roll it on the glass plate using your figures. The pressure of rolling should be just enough to make thread of uniform diameter throughout its length. The rate of rolling shall be between 60 to 90 strokes per min.

3.        Continue rolling until you get the thread diameter of 3 mm.

4.        If the thread does not crumble at a diameter of 3 mm, kneed the soil together to a uniform mass and re-roll.

5.        Continue the process until the thread crumbles when the diameter is 3 mm.

6.        Collect the pieces of the crumbled thread for moisture content determination.

7.        Repeat the test to at least 3 times and take the average of the results calculated to the nearest whole number.

PRESENTATION OF DATA

Average Plastic Limit =...............

Plasticity Index(Ip) = (LL - PL) =............       

Toughness Index =Ip/I_F =