1. In unbound sub-base layer, how many layers must the sub-base be composed of?
a) two
b) four
c) Three
d) One
Explanation: As per IRC:37-2012, the unbound sub-base can be composed of two layers. The bottom layer forms the separation layer and the top layer serves as the drainage layer.
2. What does MORTH stand for?
a) Ministry of Road Traffic and Highways
b) Model of Road Transit on Highways
c) Ministry of Road Transport and Highways
d) Model of Road Traffic in Highways
Explanation: MORTH stands for Ministry of Road Transport and Highways. It is the apex organization under the Central Government of India, that formulates policies for the road transportation system. They provide guidelines and specifications on the materials, construction, maintenance, etc. of roadways.
3. One of the functions of the sub-base is to provide a working platform for construction.
a) true
b) false
Explanation: Sub-base is a layer that is provided when the subgrade is weak. When provided, it can be used as a working platform for the construction of the most important layer – the base course. Sub-base has better quality material than subgrade, but lesser quality than the base course.
4. The higher the aggregate to cement ratio, the ______ the concrete will be in case of lean concrete.
a) Richer
b) Leaner
c) Smoothest
d) Roughest
Explanation: Lean concrete comprises of a mix consisting of a lower amount of cement than the amount of liquid in the strata. A higher ratio of aggregate to cement indicates that the mix is leaner. The water content is high and hence can be used to stabilize the soil in roadworks.
5. What does WBM stand for?
a) Water Based Macadam
b) Water Bound Macadam
c) Wet Bituminous Macadam
d) Wet Bound Macadam
Explanation: WBM stands for Water Bound Macadam. It is used as a base course. It consists of stone aggregates, screening material, and binders that are laid in the respective order.
6. The method of boulder soling is still used and it is laid over the subgrade.
a) true
b) false
Explanation: The method of boulder soling is an old practice and it is no longer employed. The reason behind this is the fact that these have proved to result in poor performance and the pavement has an undulated surface.
7. Which of the below is not used as an unbound sub-base material?
a) Kankar
b) Gravel
c) Lime-fly ash
d) Crushed slag
Explanation: Unbound sub-base is basically granular sub-base. It is made using natural moorum, sand, gravel, crushed slag, crushed stone, kankar, laterite and reclaimed crushed concrete/asphalt. The bound sub-base makes use of materials that are chemically stabilized using cement, lime-fly ash or commercial stabilizers.
8. What is the name of the layer laid in between concrete slab and sub-base course in a rigid pavement?
a) Differential layer
b) Differential membrane
c) Separation layer
d) Separation membrane
Explanation: Separation membrane is the layer laid in between sub-base and concrete slab. It serves the purpose of preventing the new layer of the concrete slab from sticking to the lean concrete sub-base.
9. Which of the below IRC codes gives the guidelines for wet mix macadam?
a) IRC 102
b) IRC SP 102
c) IRC SP 100
d) IRC 109
Explanation: IRC 109 is the code that gives guidelines for wet mix macadam. IRC 102 deals with the traffic studies for planning bypasses around towns. Guidelines for design and construction of reinforced soil walls is obtained from IRC SP 102. IRC SP 100 gives the details on the use of cold mix technology in construction and maintenance of roads using bitumen emulsion.
10. In which country was the first macadam road built?
a) USA
b) Scotland
c) Netherlands
d) Russia
Explanation: The idea of macadam road was pioneered by Scottish engineer John McAdam. The first road to be built using this technique was in the USA between Hagerstown and Boonsborough, Maryland in 1823. It was a 16 km long stretch of road.