1. ______ method can be used to obtain stable in-situ soil without admixtures.
a) Meshing
b) Mixing
c) Proportioning
d) Blending
Explanation: Using the method of proportioning, the in-situ soil and locally available aggregates can be mixed in such proportions to obtain a stable mix. This is a trial and error process, which requires the testing of various mix proportions of soil and aggregate mix.
2. What does HRB stand for?
a) Hot Reaction Base
b) High Resistance Bitumen
c) Heavy Reinforcement Base
d) Highway Research Board
Explanation: 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.
3. Organic stabilizers are found to be long lasting.
a) true
b) false
Explanation: 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.
4. ______ geotextile is preferred in soil stabilization works.
a) Knitted
b) Woven
c) Non-woven
d) Grid
Explanation: 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.
5. Which of the below cannot be used as a water retaining agent?
a) Potassium carbonate
b) Calcium chloride
c) Silica
d) Sodium hydroxide
Explanation: 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.
6. 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
Explanation: 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.
7. 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
Explanation: 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.
8. 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
Explanation: 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.
9. Black cotton soil can become non-plastic if an appropriate amount of lime is added to it.
a) true
b) false
Explanation: 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. Which is the most common method of waterproofing in soils?
a) Bitumen
b) Concrete
c) Polymer
d) Geotextile
Explanation: 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.