Pavement Design MCQs on “Soil-Cement Stabilization – 2”.
1. Which type of soil-cement becomes waterproof and UV resistant when it dries up?
a) Acrylic copolymer
b) Cement treated base
c) Soil cement base
d) Cement modified soil
Answer: a
Clarification: Acrylic copolymer is a type of water-soluble acrylic polymer. Hence it is able to penetrate into the soil and bind the particles together. This makes the mix to become waterproof and UV resistant when it dries up.
2. What is the maximum loss in the soil-cement mix after 12 cycles of freeze/thaw test for soil type A-7?
a) 10%
b) 14%
c) 7%
d) 5%
Answer: c
Clarification: As per the PCA system of mix design, which is based on durability test results, the maximum loss after conducting 12 cycles of freeze/thaw test has been specified for each soil type based on HRB soil classification. It is 14% for soil types A-1, A-3, A-2-4 and A-2-5; 10% for soil types A-2-6, A-2-7, A-4 and A-5; 7% for soil types A-6 and A-7.
3. What does FDR stand for?
a) Full Distance Reclamation
b) Full Depth Reclamation
c) Full Distance Renovation
d) Full Depth Renovation
Answer: b
Clarification: FDR is a special case of soil-cement stabilization. It utilizes the old bituminous surface and the base material to form aggregates for the cement stabilized mix by pulverizing and recycling them.
4. Cement stabilized roads are commonly cured by spraying a bituminous material over it.
a) True
b) False
Answer: a
Clarification: Cement stabilized roads can be cured using two commonly used methods – bituminous spraying and covering with moist soil. It is necessary to have a certain amount of water retained after curing.
5. The design cement content is taken as that cement content corresponding to a strength of ______
a) 28 kg/cm2
b) 17.5 kg/cm2
c) 35 kg/cm2
d) 19.5 kg/cm2
Answer: b
Clarification: According to the British method of mix design, a graph is plotted between the cement content and the compressive strength. For areas of light to medium traffic, the design cement content is taken as that corresponding to 17.5 kg/cm2 compressive strength. For heavy traffic areas, it is taken as the cement content corresponding to the compressive strength in between 28 to 35 kg/cm2.
6. How is the strength of the mix related to the extent of pulverization?
a) Not related
b) Linearly related
c) Inversely related
d) Quadratically related
Answer: b
Clarification: It is important to pulverize the mix properly and ensure that there are no dry lumps found in the mix. Pulverization and the strength of the mix are linearly related to each other. The better the extent of pulverization, the better the strength would be.
7. Which of the below bodies has published a handbook on soil-cement construction?
a) PCA
b) HRB
c) BIS
d) IRC
Answer: a
Clarification: PCA stands for the Portland Cement Association. It is an association for the American cement manufacturers. It published the soil-cement construction handbook in 1956.
8. Which of the below step is specific to mixed-in-place type construction of soil-cement?
a) Mixing
b) Compacting
c) Curing
d) Spreading cement
Answer: d
Clarification: There are two methods for the construction of soil-cement and they are mixed-in-place and central mixing plants. The step of spreading cement is specific to the mixed-in-place type construction. All other steps are common to both the construction procedures.
9. The degree of mixing is measured in terms of mixing efficiency.
a) True
b) False
Answer: a
Clarification: Mixing efficiency is expressed as a percentage of the strength of specimen prepared from field mix to the strength of that prepared from thoroughly remixed laboratory specimen. A higher degree of mixing will provide a stronger mix.
10. By what percentage can the thickness of the granular base course be reduced if soil-cement is used, as per the Highway Research Board?
a) 50%
b) 75%
c) 60%
d) 45%
Answer: b
Clarification: The HRB has recommended a reduction in the thickness of about 75% in the granular base course when soil-cement is used over a weak subgrade. There are no accepted methods for the design of the thickness of the soil-cement base course.
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