# Pavement Design Questions and Answers – Construction of Rigid Pavement – 2

This set of Pavement Design online test focuses on “Construction of Rigid Pavement – 2”.

1. What is a concrete mix partially mixed in a plant and a mixer called?
a) Transit mix
b) Partial mix
c) Shrink mix
d) Semi mix

Explanation: In the case of shrink mix, the ingredients are fed into the central mix plant and mixed partially after which it is transferred into the truck mixer and final mix is obtained. Transit mix is the one where all the mixing is carried out in the truck mixer.

2. Cement grouted and rolled concrete are suitable for which course?
a) Surface
b) Base
c) Sub-base
d) Binder

Explanation: There are different techniques or specifications for the construction of the cement concrete pavement. Cement grouted layer and rolled concrete layer are types of the same. These are all applicable in the base course only.

3. What is the recommended thickness of the separation layer that is to be provided between slab and DLC?
a) Maximum thickness of 125 micron polythene
b) Maximum thickness of 125 mm polythene
c) Minimum thickness of 125 micron polythene
d) Minimum thickness of 125 mm polythene

Explanation: A separation layer is usually provided between the sub-base and the slab. This is done to reduce the friction between the layers and provide a smooth riding surface. As per IRC 15:2002, the recommended thickness of the separation layer provided between the slab and dry lean concrete sub-base (DLC) is a minimum of 125 micron polythene.

4. Which type of steel forms are used for the placing of concrete?
a) MS angle
b) MS channel
c) MS plates
d) MS I

Explanation: Steel forms made of MS channel sections are used for placing the concrete and constructing the slab. The depth of the section determines the thickness of the slab. Channel sections have the legs that can act as a confining side of the form.

5. Which of the below is not a tool used for finishing works?
a) Internal vibrator
b) Float
c) Belt
d) Straight edge

Explanation: Internal vibrator is an equipment used for the compaction of concrete in the formwork. It is not used for finishing works. The tools used for finishing works are a float, belt, straight edge and fibre brush.
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6. Which of the below methods is not used as an initial curing method?
a) Soil berm
b) Cotton
c) Jute
d) Burlap

Explanation: There are two phases of curing the cement concrete slab – initial and final curing. The initial curing is done by using burlap, cotton or jute mats which are completely saturated with water and laid on top of the slab. Final curing is done using soil berm and impervious membrane methods.

7. In cement grouted layer, the ratio of cement to sand is taken in the range of ______
a) 1:1.5 to 1:2.5
b) 1:2 to 1:2.5
c) 1:1.5 to 1:2
d) 1:1 to 1:2

Explanation: The materials used in the cement grouted layer are coarse sand, cement and water. The grout must be in such a consistency so as to allow easy flowing and pouring. The ratio of cement to sand varies from 1:1.5 to 1:2.5.

8. A fibre brush is used to make broom marks on the surface of the pavement.
a) True
b) False

Explanation: Fibre brush is a finishing tool that is used to make broom marks on the pavement surface. It is done so to serve as a skid-resistant surface. The marks will provide friction to the wheels of the vehicle and prevent skidding.

9. Which of the below is an advantage of using the alternate bay method?
a) Less construction cost
b) Easy joint construction
c) Good drainage characteristics
d) Less disruption of traffic

Explanation: The alternate bay method has many disadvantages. The requirement for transverse joints is high and the construction cost is hence increased. The rainwater collects on the subgrade in between the alternate slabs decreasing drainage quality. Traffic is completely stopped because of the way of construction. The advantage is that the construction of joints becomes easier.

10. Hand consolidation or compaction is done in pavements that cater to the low volume of traffic.
a) True
b) False

Explanation: Hand compaction is done in areas where the width of the slab is very small such as the corners of the junction. In such areas, the mechanical compactor cannot be employed and hence the need for hand compaction arises.

Sanfoundry Global Education & Learning Series – Pavement Design.

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