Atterberg Limits Test: Liquid Limit, Plastic Limit

Atterberg Limits Test: Liquid Limit, Plastic Limit


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Introduction

Atterberg Limits Test : Limits of liquids (LL) It’s the percentage moisture content at which a soil changes from liquid to plastic consistency or from plastic to liquid consistency when wetness decreases or increases. When a soil’s water content reaches a certain level, it transitions from plastic to liquid.

The plastic limit (PL) is the water content in percent at which a soil can no longer be bent without collapsing when rolled into 3 mm diameter threads. In other words, it is the percentage moisture content at which a soil goes from a plastic to a semi-solid consistency or from a semi-solid to a plastic consistency when the wetness decreases.

This testing method is used to describe fine-grained fractions of soils and to specify the fine-grained fraction of building materials in numerous engineering categorization systems. Soil qualities such as compressibility, permeability, compatibility, shrink-swell, and shear strength are correlated with engineering behavior using the liquid limit, plastic limit, and plasticity index, either alone or in combination with other soil parameters.

Objective

The main objective of this testis to determine the liquid limit and plastic limit which are known as atterberg limits.

Liquid Limit

Apparatus : Atterberg Limits Test

  1. Casagrande Liquid limit Device.
  2. Grooving tool.
  3. Moisture cans.
  4. Porcelain evaporating dish.
  5. Spatula.
  6. Oven.
  7. Balance sensitive up to (0.01g)
  8. Plastic squeeze bottle.
  9. Paper towels.

Procedure

  1. The moisture cans’ weights (W1) were measured and recorded.
  2. The evaporating dish was filled with about 250g of soil sample that had passed through a 4.75mm sieve.
  3. Then water was added from a plastic squeeze bottle and the soil was mixed thoroughly to form a uniform paste.
  4. The created paste was poured in the liquid limit device’s metal cup, and the soil was distributed with a spatula.
  5. The soil surface was smoothened and the section in the cup was cut down to around 8mm depth.
  6. The soil in the cup was then cut across the center line using a grooving tool to create a sharp groove.
  7. By spinning the liquid limit device’s crank at a pace of roughly 2rps, the cup was lifted and down until the two sides of the soil connected.
  8. Simultaneously, the number of blows was tallied and recorded.
  9. A representative soil sample was removed from the cup and placed in a moisture container, which was then closed.
  10.  The weight of the can containing soil sample (W2) was then calculated and recorded.
  11. The remaining soil in the cup was transferred to the evaporating dish, and the cup was thoroughly cleaned with paper towels.
  12.  The soil paste was then re-mixed after water was added to the evaporating dish.
  13.  The test was done three more times with various moisture content for a total of 15 to 35 blows.
  14. The soil thread pieces with moisture container were kept in the oven for about 24 hours.
  15. The moisture container containing dry soil thread pieces was measured after 24 hours and recorded as W3.

Calculations : Atterberg Limits Test

Atterberg Limits Test
Atterberg Limits Test
Atterberg Limits Test
Atterberg Limits Test
Atterberg Limits Test
Atterberg Limits Test
Atterberg Limits Test
Atterberg Limits Test
Atterberg Limits Test

Plastic Limit

Apparatus

  1. Porcelain evaporating dish
  2. Spatula
  3. Plastic squeeze bottle with water
  4. Moisture can
  5. Ground glass plate
  6. Balance sensitive up to 0.01g

Procedure : Atterberg Limits Test

  1. The evaporating dish was filled with about 250g of soil sample that had passed through a 4.75mm sieve.
  2. The moisture cans’ weights (W1) were measured and recorded.
  3. Then water was added from a plastic squeeze bottle and the soil was mixed thoroughly to form a uniform paste.
  4. Squeezing the sol with fingers prepared several ellipsoidal-shaped soil masses.
  5. The ellipsoidal soil mass was rolled on a ground glass until it reached a diameter of around 3mm.
  6. Break the thread into multiple pieces and put them in the moisture container after it has reached a diameter of 3mm.
  7. The mass of a moisture can with soil thread pieces was recorded as W2.
  8. The soil thread pieces with moisture container were kept in the oven for about 24 hours.
  9. The moisture container containing dry soil thread pieces was measured after 24 hours and recorded as W3.

10.) Finally, all of the used equipment was cleaned.

Calculations : Atterberg Limits Test

Atterberg Limits Test
Atterberg Limits Test

Discussion : Atterberg Limits Test

 Liquid limit test and plastic limit test is very important tests that helps to classify the soils. The liquid limit and plastic limit may different from soil to soil. Not only that these limits are helps to find the plasticity index of the soil. In here we got the liquid limit as 19.57 it is saying that the soil sample that we took was behave as liquid in this range. Plastic limit is 25 and it says at the 25 soil is change from plastic limit to semisolid state. Plasticity index is the size of range of water contents where the soil exhibits plastic properties. In this practical we got it as -5.43.  As we got negative value it says that the soil sample is drier than the plastic limit.

Conclusion

Those soil limits are a significant attribute of fine-grained soil, and their value is used to define fine-grained soil and compute clay activity and soil hardness. Furthermore, it provides information on the consistency of the soil on-site. It may also be used to anticipate the consolidation qualities of soil when estimating the foundation’s permitted bearing capacity and settling.

Results and analysis for water content test

Atterberg Limits Test
Atterberg Limits Test

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