The shrinkage limit of soil is a term used in soil science to describe the water content of soil when it becomes fully saturated and all its pores are filled with water. At this point, the soil has reached its maximum volume and any further reduction in water content will not cause any further decrease in volume.
Determining the shrinkage limit of soil is an important task for soil scientists as it provides valuable information about the soil’s physical properties. It can be calculated by studying the relationship between the soil’s volume and water content.
By understanding the shrinkage limit, soil scientists can better understand how soil behaves under different conditions and how it will respond to changes in moisture levels. This knowledge is essential for various applications in agriculture, engineering, and construction, where soil stability and water content are critical factors to consider.
The context given in the question is a set of variables and their corresponding descriptions. These variables include M1, V1, Ms, and V2.
M1 represents the initial wet mass of a substance or material. V1, on the other hand, represents the initial volume of the substance. Ms stands for the dry mass of soil, which means the mass of the soil after all the moisture has been removed. Finally, V2 represents the volume of the substance after it has been dried.
In summary, the given context describes the variables used to measure the wet and dry mass and volume of a substance, specifically soil. The variables M1 and V1 are used to measure the initial wet mass and volume, while Ms and V2 are used to measure the dry mass and volume after the moisture has been removed.
Determination of Shrinkage Limit of Remoulded Soil
Equipment for Shrinkage Limit Test
The equipment list includes a shrinkage dish with a flat bottom, measuring 45mm in diameter and 15mm in height. Two large evaporating dishes, each with a flat bottom and a pour-out feature, are also included. These dishes are about 120mm in diameter. Additionally, a small mercury dish with a diameter of 60mm is included.
Two glass plates are provided, one of which is plain while the other has prongs. Both plates measure 75mm by 75mm and are 3mm thick. A glass cup measuring 50mm in diameter and 25mm in height is also included.
An IS sieve with a mesh size of 425micron is provided for particle size analysis. An oven is included for drying samples, and a desiccator is provided for moisture control.
A weighing balance with an accuracy of 0.01g is available for precise measurement of samples. A spatula and a straight edge are also provided for sample handling and preparation.
Finally, mercury is included as a substance for use in experiments or analysis.
Procedure of Shrinkage Limit Test
To determine the volume changes in a soil sample, a specific procedure must be followed. Firstly, a sample of approximately 100g from a thoroughly mixed soil passing a 425 micron sieve must be taken. Then, about 30g of this soil sample is mixed with distilled water in a large evaporating dish to create a creamy paste that can be readily worked without entrapping air bubbles.
Next, a shrinkage dish is cleaned and its mass is determined. The dish is then filled with mercury and excess mercury is removed by pressing a plain glass plate over the top of the dish, ensuring that no air is entrapped. The mercury from the shrinkage dish is then transferred to a mercury weighing dish and its mass is determined with an accuracy of 0.1g.
The volume of the shrinkage dish can be determined by dividing the mass of the mercury in grams by the specific gravity of mercury (13.6). The inside of the shrinkage dish is coated with a thin layer of silicon grease or Vaseline before placing the soil specimen in the center of the dish, equal to about one-third the volume of the shrinkage dish. The dish is tapped on a firm cushioned surface and excess soil paste is allowed to flow to the edges.
More soil is added and tapping is continued until the shrinkage dish is completely filled and excess soil paste projects out of its edge. The top surface of the plate is then struck out with a straight edge, and all soil adhering to the outside of the shrinkage dish is wiped off. The mass of the wet soil (M1) is then determined.
The soil in the shrinkage dish is then dried in air until the color of the pat turns from dark to light. It is then dried in an oven at 105 to 110 0C to constant mass. The dry pat is cooled in a desiccator and its mass, along with the shrinkage dish, is determined.
To determine the volume of the dry pat (V2), a glass cup is placed in a large evaporating dish and filled with mercury. Excess mercury is removed by pressing a glass plate with prongs firmly over the top of the cup. The dry pat of soil is then immersed in the glass cup full of mercury, taking care not to entrap air under the pat. The mercury displaced by the dry pat is collected in the evaporating dish and transferred to the mercury weighing dish to determine its mass with an accuracy of 0.1g.
It is important to repeat this test at least three times to ensure accuracy in the volume measurements.
Fig: Stages for derivation of Shrinkage Limit
Fig: Determination of volume of dry pat
Data Sheet for Shrinkage Limit Test
| Sl. No. | Observations and Calculations | Determination No. | ||
| 1 | 2 | 3 | ||
| Observation | ||||
| 1 | Mass of empty mercury dish | |||
| 2 | Mass of mercury dish, with mercury equal to volume of the shrinkage dish | |||
| 3 | Mass of mercury = (2) – (1) | |||
| 4 | Volume of shrinkage dish V1= (3)/13.6 | |||
| 5 | Mass of shrinkage dish | |||
| 6 | Mass of shrinkage dish + wet soil | |||
| 7 | Mass of wet soil M1= (6) – (5) | |||
| 8 | Mass of shrinkage dish + dry soil | |||
| 9 | Mass of dry soil Ms= (8) – (5) | |||
| 10 | Mass of mercury dish + mercury equal to in volume of dry pat | |||
| 11 | Mass of mercury displaced by dry pat =(10) – (1) | |||
| 12 | Volume of dry pat V2= (11)/13.6 | |||
| Calculations | ||||
| 13 | Shrinkage limit, | |||
| 14 | Shrinkage ratio, | |||
| 15 | Volumetric shrinkage  | |||
Results of Shrinkage Limit Test
Shrinkage limit = _____%.