For proper field control, which of the following methods is best suited for quick determination of water content of a soil mass
Calcium carbide method - It is a method for rapid determination of water content from the gas pressure developed by the reaction of calcium carbide with the free water of the soil. Shake until the pressure gauge reading is constant and note the reading. Usually it takes 4 to 8 minutes to achieve constant reading
A pycnometer is used to determine
Pycnometer is used to determine water content and specific gravity.
Stoke’s law is valid only if the size of particle is
Assumptions Stoke’s law: 1. Soil particles are spherical 2.Particle settle independent 3. Wall of jar no affect the settlement 4. Particle size between 0.0002 mm and 0.2 mm
In hydrometer analysis for a soil mass
The hydrometer method of sedimentation analysis is differs from the pipette analysis mainly in
Particle size Analysis by two methods – 1. Sieve analysis ( For coarse grain soil > 75u) 2. Sedimentation analysis ( For fine grain soil < 75u) a) Pipette method b) Hydrometer analysis
Which of the following is a measure of particle size range
a. Effective size D10 b. Uniformity coefficient (Cu = D60/D10) – Particle size c. Coefficient of curvature (Cc = D30^2/D60.D10) – Particle shape
Which of the following statements of correct
a. Uniformity coefficient represents the Size of particles b. For well graded soil, Cu > 4 Cc = 1 to 3 c. Well graded or uniformly graded – soil contains the particles of different sizes in good proportion.
Uniformity coefficient of a soil is
For a uniformly graded soil Cu is nearly unity For well graded gravel, Cu > 4 For well graded sand, Cu > 6
According to Atterberg, the soil is said to be of medium plasticity if the plasticity index PI is
Plasticity Index = Liquid Limit – Plastic Limit. PI = 0 - Nonplastic. PI 17 - Highly plastic
If the natural water content of soil mass lies between its liquid limit and plastic limit, the soil mass said to be in
Upto Shrinkage limit is Solid state. Between shrinkage and plastic limit is semi solid state. Between plastic and liquid limit is plastic state. beyond liquid limit is liquid state.
The ratio of (Liquid Limit – Water Content)/(Plasticity Index) for a soil mass is called
Plasticity index = Liquid limit(LL) – Plastic limit (PL) a. Liquidity Index = (W - PL) / PI c. Consistency Index = (LL – W) / PI d. Toughness Index = PI / Flow index
When the plastic limit of a soil is greater than the liquid limit, then the plasticity index reported as
Plasticity index is always greater than or equal to zero
Toughness index is defined as the ratio of
Toughness Index = PI/FI
If the plasticity index of a soil mass is zero, the soil is
Soil is non plastic in nature.
The admixture of coarser particles like sand or silt to clay causes
Plasticity Index = Liquid Limit – Plastic Limit
Select the correct statement
Uniformity coefficient, Cu = D60/D10. For well graded soil, Cu > 4 (Sand>6 and Gravel>4). For well graded soil, Cc = 1to 3
The following index properties were determined for four soils A, B, C and D Soil property A B C D Liquid Limit 0.50 0.49 0.43 0.47 Plastic limit 0.23 0.17 0.21 0.26 Which of these soils contains more clay particles
More the plasticity index value higher the clay particles. Plasticity index = Liquid Limit – Plastic Limit Soil A, PI = 0.50 – 0.23 = 0.27 Soil B, PI = 0.49 – 0.17 = 0.32 Soil C, PI = 0.43 – 0.21 = 0.22 Soil D, PI = 0.47 – 0.26 = 0.21
The water content of soil, which represents the boundary between plastic state and liquid state, is known as
Which of the following soils has more plasticity index
Plasticity index is more for fine soil. Clay > Silt > Sand > Gravel
At liquid limit, all soils possess
Same shear strength and small magnitude 2.70 KN/m²
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