Pavement Design Multiple Choice Questions on “Soil Stabilization – 2”.
1. What does HRB stand for?
a) Hot Reaction Base
b) High Resistance Bitumen
c) Heavy Reinforcement Base
d) Highway Research Board
Answer: d
Clarification: HRB stands for Highway Research Board. The soil classification for the stabilization process is done with the help of HRB classification system. Another system used is the revised PRA system.
2. ______ geotextile is preferred in soil stabilization works.
a) Knitted
b) Woven
c) Non-woven
d) Grid
Answer: b
Clarification: Woven geotextiles are made by weaving polypropylene or polyester fibres together. These provide better resistance against breaking because of their strong interlocking between fibres. These are useful in soil stabilization as they have great tensile strength.
3. Which of the below cannot be used as a water retaining agent?
a) Potassium carbonate
b) Calcium chloride
c) Silica
d) Sodium hydroxide
Answer: c
Clarification: Water retaining agents can be used in soils that improve their property in the presence of some amount of water. It is applicable to non-cohesive soils only. Silica is not a water retaining substance, it absorbs water. All other options indicate deliquescent materials.
4. Organic stabilizers are found to be long lasting.
a) True
b) False
Answer: b
Clarification: Organic stabilizers are a good option if they are not affected by moisture content. They get knocked down easily by rainwater and this can be prevented by providing a bituminous coating. Commonly used organic stabilizers are sodium silicate, lignin, resin and molasses.
5. What is the essential feature to be checked in case of reinforced earth technique of soil stabilization?
a) Friction
b) Shear
c) Compression
d) Tension
Answer: a
Clarification: It is the friction between the reinforcement and the soil that is made use of in this particular technique. The soil transfers the force to the reinforcement by means of friction. The reinforcement is provided in the form of thin strips and is laid in the soil.
6. Which type of soil sample can be used to test consolidation, permeability and shear strength tests?
a) Non-representative
b) Undisturbed
c) Representative
d) Disturbed
Answer: b
Clarification: Soil samples can be of two type – representative and non-representative. Disturbed and undisturbed samples are types of representative samples. In undisturbed soil samples, in-situ structure and moisture content are retained and hence it can be used to test the engineering properties.
7. What does LCF used for stabilization stand for?
a) Lime Cement Fibre
b) Light Cement Fly ash
c) Lean Cement Film
d) Lime Cement Fly ash
Answer: d
Clarification: LCF is a combination of lime, cement and fly ash used to stabilize the soil. It consists of proportioned amounts of all three stabilizers that are added to provide bearing strength to the soil.
8. Which is the most common method of waterproofing in soils?
a) Bitumen
b) Concrete
c) Polymer
d) Geotextile
Answer: a
Clarification: In some soil types, the water flowing into the voids may weaken it. Therefore, it is necessary to waterproof them. The most common and effective method is using bituminous materials.
9. Black cotton soil can become non-plastic if an appropriate amount of lime is added to it.
a) True
b) False
Answer: a
Clarification: Black cotton soils have high plasticity and are also highly expansive in nature. Stabilization can be effective by adding the right proportion of lime to the soil, it reduces the plasticity index of soil to almost zero and can make it behave like a non-plastic soil.
10. What is the best possible method to stabilize desert sand?
a) Proportioning
b) Lime
c) Cement
d) Bitumen
Answer: d
Clarification: There is a problem of water scarcity and soil-cement stabilization method cannot be used. Desert sand consists of fine sand particles and proportioning is difficult. Lime is also not employed. So, hot sand-bitumen is the most possible and preferred method.