1. If the aggregate impact value lies between 10 – 20%, the aggregate is said to be ______
a) Exceptionally tough
b) Very tough
c) Good for surface course
d) Weak
Explanation: After the impact test is conducted, the results are obtained in percentage. The aggregate is said to be exceptionally tough when the value is <10%, very tough when the value is in between 10 - 20%, good for pavement surface when the value is in between 20 – 30% and weak if the value is >35%.
2. Which of the below formula is used to find out the angularity number?
a) AN=67-\(\frac{100W}{CG_a}\)
b) AN=76-\(\frac{10W}{CG_a }\)
c) AN=76-\(\frac{100W}{CG_a}\)
d) AN=67-\(\frac{10W}{CG_a }\)
Explanation: Angularity number is defined as the 67 – percent solid volume of aggregates. If a well compacted single sized round aggregate is considered, it is found to have 67% solid volume and 33% voids. Angularity number is expressed in terms of voids in such a sample.
3. Which IS code gives the guidelines to perform the aggregate tests?
a) IS 2309
b) IS 2386
c) IS 2720
d) IS 2835
Explanation: IS 2386 has eight parts, each part gives the guidelines for various tests to be performed on the aggregates. IS 2309 gives details on the protection of buildings against lightning. IS 2720 deals with soil tests and IS 2835 deals with flat transparent sheet glass
4. In the crushing test, what is the compressive load subjected to the specimen?
a) Gradual 40 kN
b) Gradual 40 tonnes
c) Rapid 40 kN
d) Rapid 40 tonnes
Explanation: The sample filled mould is placed under the compression testing machine and a compressive load of 40 tonnes is applied gradually. The loading rate is 40 tonnes per minute. The aggregates get crushed over time with the passage of the vehicle, so the load is applied gradually.
5. Flakiness index test is applicable to particle sizes larger than ______
a) 6.5 cm
b) 6.3 cm
c) 6.5 mm
d) 6.3 mm
Explanation: Flakiness index is the percentage by weight of aggregate pieces, the least dimension of which is less than 0.6 of their mean dimension. There is a thickness gauge available for finding the flakiness index.
6. What is the range in which the specific gravity of rocks varies?
a) 2.1 to 2.6
b) 2 to 3
c) 2.6 to 2.9
d) 3 to 3.5
Explanation: As per IS 2386 part 3, the range of specific gravity for coarse aggregates varies from 2.6 to 2.9. The aggregates in this range can be used for roadworks as well as for concrete works.
7. A sample of weight 2731 g was subjected to crushing test after which, the weight of sample passing the sieve was found to be 761 g. What will be the crushing value of the sample?
a) 28%
b) 27%
c) 28
d) 27
Explanation: Aggregate crushing value is found as the percentage ratio of the weight of the sample passing the sieve to the original weight of the sample. So, the aggregate crushing value for the above sample would be \(\frac{761}{2731}\)×100%=27.86%\(\approx\)28%. The value is rounded off to nearest whole number and is expressed in percentage.
8. The polished stone test is conducted in two stages. Which is the first stage?
a) Friction test
b) Polishing
c) Grinding
d) Scrubbing
Explanation: The first stage is where the sample is filled in the mould and subjected to accelerated polishing in a machine. In the second stage, the polished stone is subjected to the friction test.
9. The stripping test method was developed by ______
a) BIS
b) IRC
c) AASHTO
d) RRL
Explanation: The method to analyse the adhesion of binder to aggregate was developed by the Road Research laboratory RRL, England. The method used in India now has been standardized by BIS.
10. The mould of size with an inner diameter of 102 mm and a depth of 50 mm is used in which test?
a) Impact test
b) Durability test
c) Abrasion test
d) Crushing test
Explanation: The impact test is carried out on a sample filled in a mould with an inner diameter 102 mm and depth as 50 mm. There is no mould used in the durability, abrasion test. For crushing test, the mould used is cylindrical with a diameter of 115 mm and a height of 180 mm.