1. The indirect method of determining viscosity is not applicable to which of the below?
a) Tar
b) Cut-back bitumen
c) Modified bitumen
d) Bitumen emulsion
Explanation: The indirect test consists of the determination of time taken by 50 mL of sample in the fluid state to flow through an orifice in a cup. This is carried out under standard test conditions and specified temperatures. Modified bitumen consists of additives and cannot be subjected to this test.
2. Softening test was performed on a bitumen sample and it was found out to be 62°. Which grade does it belong to?
a) VG 10
b) VG 20
c) VG 30
d) VG 40
Explanation: In IS 73:2013, the softening point of various grades of bitumen are noted down. There are four grades of bitumen and corresponding softening points are mentioned in the code. For VG 10, it is 40; for VG 20 – 45; for VG 30 – 47 and for VG 40 – 50.
3. ______ mould is used for conducting the ductility test
a) Block
b) Briquette
c) Urethane
d) Latex
Explanation: Briquette mould is metallic and can be split into two halves. Bitumen is filled in the mould after it is fixed properly. Block mould is made of silicone and can be used for casting items. Urethane mould and latex mould can be used for casting concrete or plastic.
4. Which IS code is referred to for conducting the float test for bitumen?
a) IS 1209
b) IS 1211
c) IS 1210
d) IS 1212
Explanation: IS 1210-1978 is used to refer to procedure and specifications for conducting float test. IS 1209 is used for flash and fire point test, IS 1211 for determination of water content and IS 1212 for determination of loss on heating
5. ______ viscosity is the ratio between applied shear stress and the rate of shear.
a) Normal
b) Apparent
c) Kinematic
d) Absolute
Explanation: Absolute viscosity is also known as the coefficient of friction and dynamic viscosity. Kinematic viscosity is the ratio of absolute viscosity to density.
6. Ductility of bitumen is measured in terms of ______
a) Time
b) Distance
c) Temperature
d) Colour
Explanation: Ductility of bitumen is measured by the distance by which the bitumen gets elongated before breaking. It is expressed in cm. the sample in the mould is allowed to stretch gradually and the distance is read using the scale in the apparatus.
7. At what rate is the temperature applied during the softening point test?
a) 5° per minute
b) 5° per hour
c) 6° per minute
d) 6° per hour
Explanation: The guidelines to conduct the softening point test are given in the IS code 1205-1978. As per the code, the rate of applying the temperature increase to the sample is 5° per minute. The test is allowed to continue till the bitumen softens and that temperature is noted.
8. Which of the below tar type – application pairs matched correctly?
a) RT-1 – renewal coat
b) RT-2 – standard surface painting
c) RT-3 – cold weather surface painting
d) RT-4 – grouting
Explanation: Tar can be of five types based on its viscosity. They are RT-1, RT-2, RT-3, RT-4 and RT-5. RT-1 has the least viscosity and is used for surface painting in extremely cold weather, RT-2 is used for standard surface painting in Indian climate, RT-3 is used for renewal coats, RT-4 is used for premixing tar macadam in the base course and RT-5 is used for grouting.
9. From where is the paving bitumen grade A35 is obtained?
a) Saudi Arabia
b) Asia
c) Assam
d) Andhra Pradesh
Explanation: All the bitumen extracted from Assam petroleum are denoted by the letter A and their grade is denoted by numerals like 25, 35, 45, 65, 90 and 200. Bitumen from other sources are denoted by S35, S45, S65 and S90.
10. The spot test is used to determine if bitumen is ______ or not.
a) Cracked
b) Soluble
c) Strong
d) Deformed
Explanation: Spot test is a type of chromatographic test which determines if the bitumen is cracked or not. It is used to check if bitumen has been damaged by overheating.