This set of Concrete Technology Multiple Choice Questions & Answers (MCQs) focuses on “Testing of Cement”.
1. How many times in each layer of concrete rodded in a slump cone?
a) 75
b) 25
c) 12 to 15
d) 35 to 65
View Answer
Explanation: Each time, each layer is tamped 25 times with a 2 ft (600 mm)-long bullet-nosed metal rod measuring 5/8 in (16 mm) in diameter.
2. How many layers of concrete are placed to fill a slump cone?
a) 5 layers
b) 3 equal layers by volume
c) 3 equal layers by height
d) 5 layers by volume
View Answer
Explanation: Fill the mold 12 inches high in the shape of the frustum of a cone that is 8 inches in diameter at the bottom and 4 inches in diameter at the top. Then fill it in three equal layers by volume, not by height.
3. After placing each layer in a slump cone, the concrete in the cone is tapped to remove remaining voids.
a) True
b) False
View Answer
Explanation: It is good to remove the voids from the concrete to increase its strength. Therefore, tapping is needed to remove the remaining voids from the slump cone.
4. To measure the concrete temperature, the stem of the thermometer must be kept by at least ___ inches of concrete.
a) 1
b) 2
c) 3
d) 4
View Answer
Explanation: The stem of the thermometer should be surrounded by at least 3 inches of the concrete for better reading.
5. In the soundness test a specimen of hardened cement paste is ___ for a fixed time.
a) Freeze
b) Dry
c) Boiled
d) Dipped in water
View Answer
Explanation: A specimen of hardened cement paste is boiled for a fixed time so that if there is any tendency of increase or decrease in size can be detected.
6. If L1=Measurement taken after 24 hours of immersion in water at a temp. of 27 ± 20oC and L2=Measurement taken after 3 hours of immersion in water at boiling temperature. Then what is soundness of cement?
a) L1+L2
b) L1/L2
c) L1-L2
d) L1*L2
View Answer
Explanation: L1-L2 is the formula to calculate the soundness of cement. First take the reading after immersion in water then measure it after 3 hours of immersion in boiling water.
7. To determine the fineness of cement ____
a) Grain size is smaller than specified mesh size
b) Grain size is larger than specified mesh size
c) Grain size is equal to specified mesh size
d) Grain size is 1mm
View Answer
Explanation: To determine the fineness of cement by dry sieving as per IS: 4031 (Part 1) – 1996. The principle of this is that we determine the proportion of cement whose grain size is larger than the specified mesh size.
8. The apparatus used are ___ IS Sieve, Balance capable of weighing 10g to the nearest 10mg.
a) 90μm
b) 45μm
c) 22.5μm
d) 14μm
View Answer
Explanation: The apparatus used are 90μm IS Sieve, Balance capable of weighing 10g to the nearest 10mg, A nylon or pure bristle brush, preferably with 25 to 40mm, bristle, for cleaning the sieve.
9. What is the amount of water required to give the paste normal consistency for consistency test?
a) .78 times
b) .79 times
c) .77 times
d) .76 times
View Answer
Explanation: Prepare a paste by adding 0.78 times the water required to give a paste of standard consistency (i.e. 0.78P).
10. Which apparatus is generally used to measure the soundness of the cement?
a) Vicat Apparatus
b) Le-Chatelier apparatus
c) Soundness meter
d) Duff Abrams apparatus
View Answer
Explanation: The apparatus for conducting the Le-Chatelier test should conform to IS: 5514 – 1969. Balance, whose permissible variation at a load of 1000g should be +1.0g and Water bath.
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