DHARMINDEX PROPERTIES AND CLASSIFICATION TESTS 91
3.20 In a hydrometer analysis, 0.5 N of soil was mixed in water to form one litre of uniform suspen-
sion. The corrected hydrometer reading after a lapse of 60 min. from the start of sedimentation
was 1.010, and the corresponding effective depth was 10.8 cm. The grain specific gravity was
2.72. Assuming the viscosity of water as 0.001 N-sec/m^2 and the unit weight of water as
9.8 kN/m^3 , determine the co-ordinates of the corresponding point on the grain-size distribution
curve.
3.21 The liquid limit and plastic limit of a soil are 75% and 33% respectively. What is the plasticity
index? The void ratio of the soil on oven-drying was found to be 0.63. What is the shrinkage
limit? Assume grain specific gravity as 2.7.
3.22 A piece of clay taken from a sampling tube has a wet weight of 1.553 N and volume of 95.3 cm^3.
After drying in an oven for 24 hours at 105°C, its weight is 1.087 N. The liquid and plastic limits
of the clay are respectively 56.3% and 22.5%. Determine the liquidity index and void ratio of the
sample. Assume the specific gravity of soil particles as 2.75. (S.V.U—B.E., (R.R.)—Nov., 1973)
3.23 A completely saturated sample of clay has a volume of 31.25 cm^3 and a weight of 0.5866 N. The
same sample after drying has a volume of 23.92 cm^3 and a weight of 0.4281 N. Compute the
porosity of the initial soil sample, specific gravity of the soil grains and shrinkage limit of the
sample. (S.V.U.—Four-year B.Tech.—June, 1982)
3.24 In a shrinkage limit test, the following data were obtained:
Initial weight of the saturated soil = 1.928 N
Initial volume of saturated soil = 106.0 cm^3
Weight after complete drying = 1.462 N
Volume after complete drying = 77.4 cm^3
Determine the shrinkage limit, the specific gravity of soil grains, initial void ratio, bulk unit
weight, and dry unit weight and final void ratio and unit weight.
(S.V.U.—B.Tech., (Part-Time)—April, 1982)
3.25 The Atterberg limits of a clay soil are: Liquid limit = 63%, Plastic limit = 40%, and shrinkage
limit = 27%. If a sample of this soil has a volume of 10 cm^3 at the liquid limit and a volume of 6.4
cm^3 at the shrinkage limit, determine the specific gravity of solids, shrinkage ratio, and volumet-
ric shrinkage.
3.26 A 100 cm^3 -clay sample has a natural water content of 30%. Its shrinkage limit is 18%. If the
specific gravity of solids is 2.72, what will be the volume of the sample at a water content of
15%?
3.27 The oven-dry weight of a pat of clay is 1.17 N and the weight of mercury displaced by it is 0.855
N. Assuming the specific gravity of solids as 2.71, determine the shrinkage limit and shrinkage
ratio. What will be the water content, at which the volume increase is 10% of the dry volume?