Question

A container of saturated soil is 38mm dia. and 78mm long and it's mass is 142g. After over drying at 105 degrees celcius it's mass is 86g. Calculate the unit weight, water content, specific volume of the soil and the specific gravity of the grains. (Ans. 15.75kN/m3, 65.1%, 2.72, 2.64)

Answer 1

Volume of the container is (diameter, d = 38 mm = 0.038 m and length, h = 78 mm = 0.078 m)

The weight of the container is W which is expressed as

Unit weight (w) of the container is the ratio of the weight of the container and the volume of the container.

% of water in the soil will be

Volume of the soil is 88.46 cm³ and the mass of the soil is 142 g. Hence specific volume of the soil will be

I have a doubt about the answer. According to definition, the specific volume of a substance is the ratio of the volume of the substance and its mass.

Specific gravity is the ratio of the mass of a substance of unit volume and the mass of water of unit volume. The mass of water of unit volume is 1 g/cm³. Water content in the container is (142 - 86)g = 56 g. Hence the volume of the water will be 56 cm³. The volume of container is 8.846 x 10^-5 m³ or 88.46 cm³. Therefore, the volume of the grains will be (88.46 cm³-56 cm³ ) = 32.46 cm³. Hence, according to definition, the specific gravity of the grains will be