This set of Basic Civil Engineering Multiple Choice Questions & Answers (MCQs) focuses on “Sieve Analysis”.
1. The sieve sets for coarse aggregate ranges from:
Explanation: According to IS 565, the sieve sets are 80mm, 40mm, 20mm, 10mm, 4.75mm for coarse aggregates.
2. The aggregate sample for the sieve analysis is placed on:
a) Largest sieve
b) Smallest sieve
c) 40mm IS sieve
d) 4.75mm IS sieve
Explanation: Only if the sample is placed on largest sieve size, it can be sorted, according to each smaller sieve size below.
3. What is a receiver in a sieve analyser?
a) Round pan on top
b) First sieve
c) Last sieve
d) Round pan at base
Explanation: At the base of all the sieve sets, round pan is placed to collect the particles finer than the last sieve size. It is called the receiver.
4. How is percentage retained on each sieve calculated?
Explanation: The percentage retained is calculated by dividing weight of sample retained by the weight of the total sample, taken in beginning of test.
5. In how many ways can sieve analysis be carried out?
Explanation: The 5 methods are throw-action, horizontal, tapping, wet and air circular jet.
6. Under what circumstance is a wet sieve analysis carried out?
a) Sample is washed
b) Moisture content is high in sample
c) Sample contains organic matter
d) Very fine powdered sample
Explanation: Sometimes samples contain very fine powders which tend to agglomerate. In dry sieve analysis, it would lead to clogging of meshes and it makes analysis difficult.
7. Which of the below is a limitation of performing sieve analysis?
a) Time consuming
c) Particle shape
d) Particle size
Explanation: The shape of particles is assumed to be nearly round or spherical so that they pass through the square opening. For elongated, flaky particles it will be difficult.
8. A narrow gradation is also called:
a) Gap gradation
b) Uniform gradation
c) Rich gradation
d) Open gradation
Explanation: A graph is plotted after performing sieve analysis. It shows different curves. A narrow gradation is also called uniform gradation. It shows that the aggregate is of approximately the same size.
9. For how long is the mechanical vibrator shaked?
a) 15-20 minutes
b) 5 minutes
c) 10-15 minutes
d) 30 minutes
Explanation: As per IS code 2720 Part 4. Mechanical vibrator is switched on and allowed to vibrate for 15-20 minutes. It ensures proper grading of particles.
10. For fine aggregates that is, sample passing through 4.75mm IS sieve, how much sample should be taken?
a) 5 kg
b) 1 kg
c) 2 kg
d) .5 kg
Explanation: IS 2720 gives the specifications. It requires using sample weighing 5 kg for coarse aggregates and 1 kg for fine aggregates.
11. Gradation affects the properties of an aggregate.
Explanation: Gradation affects properties like bulk density, physical stability and permeability. With careful selection of the gradation, desired properties can be achieved.
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