Past Year Questions: Classification of Soils & Clay Minerals

# Past Year Questions: Classification of Soils & Clay Minerals | Soil Mechanics - Civil Engineering (CE) PDF Download

Q.1. A fine-grained soil is found to be plastic in the water content range of 26-48%. As per Indian Standard Classification System, the soil is classified as [2016: 1 Mark, Set-I]
(a) CL
(b) CH
(c) CL-ML
(d) CI

Ans. (d)
Solution: Soil is plastic in the range of 26-48%.
Hence, Plastic limit = 26% and liquid limit = 48%.
Because the liquid limit is in the range of 35% to 50%. Hence intermediate compressible soil.

Question for Past Year Questions: Classification of Soils & Clay Minerals
Try yourself:The clay mineral primarily governing the swelling behavior of Black Cotton soil is [2014: 1 Mark, Set-II]

Question for Past Year Questions: Classification of Soils & Clay Minerals
Try yourself:As per Indian Standard Soil Classification System (IS 1498: 1970), an expression for A-line is [2014: 1 Mark, Set-II]

Q.4. As per the Indian Standard soil classification system, a sample of silty clay with a liquid limit of 40% and plasticity index of 28% is classified as [2012: 1 Mark]
(a) CH
(b) CI
(c) CL
(d) CL-ML

Ans. (b)
Solution:
Ip of soil = 28%
Ip of A-line = 0.73(W- 20) = 0.73 (40 - 20) = 14.6
∵ Ip of soil > Ip of A-line
∴ It will lie above Aline and also 35 < W< 50
So it is CI.

Q.5. The results for sieve analysis carried out for three types of sand, P, Q, and R, are given in the adjoining figure. If the fineness modulus values of the three sands are given as FMP, FMQ, and FMR, it can be stated that [2011: 1 Mark]

(a) FM( FMx FM)
(b) FM= 0.5 ( FM+ FM)

(c) FMP > FMQ > FMR
(d)
FM< FMQ < FMR
Ans. (a)
Solution: The term fineness modulus is used to indicate an index number roughly proportional to the average size of a particle in the entire quantity of aggregate.

Question for Past Year Questions: Classification of Soils & Clay Minerals
Try yourself:A fine-grained soil has a liquid limit of 60 and a plastic limit of 20. As per the plasticity chart, according to IS classification, the soil is represented by the letter symbols [2010: 1 Mark]

The document Past Year Questions: Classification of Soils & Clay Minerals | Soil Mechanics - Civil Engineering (CE) is a part of the Civil Engineering (CE) Course Soil Mechanics.
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## Soil Mechanics

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## FAQs on Past Year Questions: Classification of Soils & Clay Minerals - Soil Mechanics - Civil Engineering (CE)

 1. What is the importance of soil classification and clay minerals in the field of geotechnical engineering?
Ans. Soil classification and clay minerals play a crucial role in geotechnical engineering as they help in understanding the properties and behavior of soils. By classifying soils, engineers can determine their suitability for construction projects, assess their stability, and design appropriate foundations. Clay minerals, on the other hand, influence the engineering properties of soils such as permeability, shrinkage, and swelling. Understanding these minerals is vital for effective soil stabilization and preventing foundation failures.
 2. How are soils classified based on their particle size distribution?
Ans. Soils can be classified based on their particle size distribution using several widely accepted classification systems. One such system is the Unified Soil Classification System (USCS), which categorizes soils into various groups based on their percentage of gravel, sand, silt, and clay particles. Another commonly used system is the AASHTO soil classification system, which is specifically designed for highway engineering purposes. These classification systems provide engineers with a standardized way to communicate and analyze soil characteristics.
 3. What are the main types of clay minerals found in soils?
Ans. The main types of clay minerals found in soils are kaolinite, montmorillonite, and illite. Kaolinite is a relatively non-plastic clay mineral and is commonly found in residual soils. Montmorillonite, on the other hand, is highly plastic and exhibits significant swelling when exposed to water. It is often found in soils with high shrink-swell potential. Illite is a mica-like clay mineral and is intermediate in plasticity between kaolinite and montmorillonite. These clay minerals greatly influence the engineering behavior of soils.
 4. How do clay minerals affect the engineering properties of soils?
Ans. Clay minerals have a significant impact on the engineering properties of soils. They can greatly influence the soil's permeability, compressibility, shear strength, and shrink-swell behavior. For example, soils with a higher clay mineral content tend to have lower permeability, making them more susceptible to waterlogging and poor drainage. Additionally, clay minerals can cause soils to exhibit high compressibility and low shear strength, which can pose challenges for construction projects and require appropriate soil stabilization techniques.
 5. What are the different methods used to identify clay minerals in soils?
Ans. Several methods are used to identify clay minerals in soils. X-ray diffraction (XRD) is a commonly used technique that provides detailed information about the mineral composition of soils. XRD analysis allows for the identification and quantification of different clay minerals present in a soil sample. Another method is the use of electron microscopy, which provides high-resolution images of clay minerals, allowing for visual identification. Additionally, various chemical tests and laboratory experiments can be conducted to determine the presence and behavior of specific clay minerals in soils.

## Soil Mechanics

30 videos|76 docs|74 tests

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