What is the density of mercury which is used in shrinkage limit test?

Explanation: The density of mercury = 13.6 g/cm3. Explanation: Vaseline prevents the formation of air-bubbles. Hence it is used as for inner coating in a shrinking dish.

Which liquid is used to find volume of soil pat in shrinkage limit test?

The volume of oven-dried soil is determined by using mercury to occupy the vacant spaces caused by shrinkage. The mass of mercury is determined and the volume decrease caused by shrinkage can be calculated from the known the density of mercury.

Which material is used in determination of shrinkage?

The volume of dry soil pat, Vd, is computed by dividing the weight of displaced mercury with the specific gravity of mercury. ASTM D-4943 describes a method of using molten wax for the determination of shrinkage limit in place of mercury, since handling mercury is hazardous.

How we can determine the shrinkage limit of soil?

To Determine The Shrinkage Limit of Soil

1. Take a soil sample passing through sieve#40 and add some amount of water in it to form a thick uniform paste.
2. Take the shrinkage dish, weigh it, and put some of the soil mixture in it by spatula, fill it and again weigh it.

What is the purpose of shrinkage limit?

This limit is needed for studying the swelling and shrinkage properties of cohesive soil. The shrinkage factor helps in the design problems of structure made up of this soil or resting on such soil. It helps in assessing the suitability of soil as a construction material in foundations, roads, embankments, and dams.

Why liquid limit test is done?

Liquid limit of soil can be used to predict the consolidation properties of soil while calculating allowable bearing capacity & settlement of foundation. Liquid limit value of soil is also used to calculate activity of clays and toughness index of soil.

Why volume of soil does not change if it is allowed to dry beyond shrinkage limit?

Soil contains mineral matter, organic matter, water and air. For any fixed volume of soil, the amount of air present in soil varies according to the water content. Therefore decreasing the water content of a soil below the shrinkage limit will increase the air content but soil volume will remain the same.

Why does shrinkage occur in soil?

Shrinking Soils Shrinkage and shrinkage cracks are caused by a reduction in soil moisture content through: Evaporation from the soil surface in dry climates. Lowering of the groundwater table. Desiccation of soil by trees during temporary dry spells in otherwise humid climates.

What is dry density of soil?

Dry density of soil is defined as the ratio of Mass of solids to the total volume of the soil. It is represented by. To obtain relationship between the moisture content and dry density, multiply the numerator and denominator of expression of dry density with “M” which is mass of soil sample.

What is a pat of soil?

The shrinkage limit of cohesive soils is defined as the water content at which further loss of moisture will not cause a decrease in volume. The soil pat is then oven-dried. After coating in melted wax, the volume of the soil pat is computed by weighing in water and noting the difference from its weight in the air.

Why is the soil air dried first before oven drying?

Suppose a soil with field capacity (0.33 tension) starts drying and reaches 1.0 tension. Then if you determine moisture content at this tension on oven dry basis it will be more than the wet soil moisture. So before determining moisture content it is necessary to air dry the soil.

How do you calculate the volume of dry soil Pat?

The glass cup is removed from the evaporating dish, and the displaced mercury in the evaporating dish is carefully weighed. The volume of dry soil pat, V d, is computed by dividing the weight of displaced mercury with the specific gravity of mercury.

What is the relationship between soil moisture content and dry density?

The soil moisture content and the degree of dry density to which the soil is prepared to be compacted maintain a definite relationship. The Optimum moisture content (OMC) or Optimum Water Content (OWC) is the moisture content at which the soil attains maximum dry density.

How to determine if the soil is wet or dry?

If the thread crumbles at diameter smaller than 3 mm, the soil is too wet. If the thread crumbles at a diameter greater than 3 mm, the soil is drier than the plastic limit. The sample can then be remolded and the test repeated. Once the appropriate size rolls are made, their moisture content is assessed using the procedure described previously.

What happens to the volume of the soil when water content decreases?

The volume of the soil does not decrease when the water content is reduced below the shrinkage limit. Shrinkage limit can be determined from the relation Where M1= initial wet mass, V1= initial volume Ms = dry mass of soil V2 = volume after drying.