GATE PSUs- Soil Engineering - One liners- Part 3

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Soil Engineering one liners - part 3.

• Uniformity co-efficient is a measure of particle size range.
• Uniformity co-efficient of soils is always equal to or greater than 1.
• According to Atterberg, the soil is said to be of medium plasticity if the plasticity index PI is greater than equal to 7 and less than or equal to 17 i.e. 7<=PT<=17.
• If the natural water content of a soil is in between the liquid limit and plastic limit then the soil is said to be in Plastic state.
• Consistency index is defined as (Liquid limit - Water content) / Plasticity Index.
• When the plastic limit of a soil is greater than the liquid limit, then the plasticity index is reported as  zero.
• Toughness index is defined as the ratio of plasticity index to flow index.
• Sand has a plasticity index equal to 0.
• The admixture of coarser particles like sand or silt to clay causes decrease in both liquid limit and plasticity index.
• A uniform soil has less strength and stability than a non-uniform soil.
• The water content of soil, which represents  the boundary between plastic state and liquid state, is known as Liquid limit.
• At liquid limit, all soils possess same shear strength of small magnitude.
• If the material of the base of the Casagrande liquid limit device on which the cup containing soil paste drops is softer than the standard hard rubber, then the liquid limit of soil always increases.
• According to IS classification the range of silt size particles is 0.075 mm to 0.002 mm.
• Sand particles are made of rock minerals.
• The clay mineral with largest swelling and shrinkage characteristics is montmorillonite. 
• Dispersed type of soil structure is an arrangement comprising particles having face to face or parallel orientation.
• Effective stress is important because it is function of engineering properties. 
• Rise of water table above ground surface causes equal increase in pore water pressure and total pressure.

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References: Google & a book titled as "Civil Engineering objective" by S P Gupta and S P Gupta.