Building Material Questions (BM8)

In this post, I will share some important questions which are frequently asked in competitive examinations such as SSC, UPSC and state PSCs.



  1. What is the height of free fall of weight in aggregate impact value test?


    1. 350 mm
    2. 380 mm
    3. 400 mm
    4. 450 mm

    View Answer
    Answer: b
    As per IS: 2386 Part 4, free fall is 380 mm

  2. Which of the following properties is determined by aggregate impact value test?


    1. Crushing Strength
    2. Toughness
    3. Hardness
    4. Soundness

    View Answer
    Answer: b

  3. After abrasion test, if the loss in weight of aggregate is 18 gram. What will be the hardness of the sample?


    1. 20
    2. 13
    3. 14
    4. 17

    View Answer
    Answer: c
    $Hardness = 20-\frac{\text{Loss in gram}}{3}=20-\frac{18}{3}=14$

  4. What is the weight of the abrasive charge used in Log Angeles Abrasion Test?


    1. 330 to 400 gram
    2. 350 to 430 gram
    3. 390 to 445 gram
    4. 400 to 480 gram

    View Answer
    Answer: c
    As per IS: 2386 Part 4, the weight of abrasive charge is 390 to 445 gram and diameter is approximately 48 mm

  5. If the grade of aggregate used in Abrasion test is "E", the number of resolutions to be given is


    1. 500
    2. 1000
    3. 1500
    4. 2000

    View Answer
    Answer: b
    As per IS: 2386 Part 4, for grade A, B, C and D, the number of resolutions is 500 and for grade E, F and G, the number of resolutions is 1000.

  6. For aggregate to be used in concrete, the percentage wear should not be more than ____ percent.


    1. 13
    2. 16
    3. 19
    4. 21

    View Answer
    Answer: b

  7. The pH of the water to be used in concrete ________.


    1. shall be less than 6
    2. shall not be less than 6
    3. shall be less than 8
    4. shall not be less than 8

    View Answer
    Answer: b
    As per IS: 456: 2000, the pH of water shall not be less than 6.

  8. Plasticizers ...


    1. get absorbed on the cement particles.
    2. increase the inter-particle friction
    3. reduces the surface tension of water
    4. none of the above

    View Answer
    Answer: c
    Plasticizers get ADSORBED on the cement particle and cement particles get deflocculated and dispersed. Thus the mix fluidifies. In dispersed condition, there is water between cement particles which REDUCES the inter-particle friction.

  9. Due to the use of Plasticizers, the reduction in water is _______.


    1. 5 to 10 %
    2. 5 to 15 %
    3. 10 to 15 %
    4. 15 to 20 %

    View Answer
    Answer: b

  10. Which of the following is used to test the compatibility of superplasticizers and cement?


    1. Marsh cone test
    2. Mini slump test
    3. Flow table test
    4. All of the above

    View Answer
    Answer: d
    Marsh cone test gives better results.

  11. The rate of slump loss of  superplasticized concrete will be ______ than that of unplasticized concrete.


    1. less
    2. little more
    3. much more
    4. none of the above

    View Answer
    Answer: b

  12. The effect of plasticizers on strength of concrete is to ...


    1. increase it
    2. decrease it
    3. no effect
    4. none of the above

    View Answer
    Answer: a
    If plasticizers which are compatible with the cement are used in right quantity, will decrease the w/c ratio and increase the strength of concrete.

  13. Common sugar is used in concrete as a/an ...


    1. accelerator
    2. retarder
    3. air entrainer
    4. none of the above

    View Answer
    Answer: b
    Common sugar is a retarding agent. At normal temperatures, an addition of sugar 0.05 to 0.10 % have little effect on the rate of hydration but if the quantity is increased to 0.2 %, it may delay the final set for 72 hours or more.

  14. Which of the following is correct regarding accelerators?


    1. It increases the overall strength of concrete
    2. It increases the rate of early strength development of concrete
    3. It increases the time period of curing
    4. none of the above

    View Answer
    Answer: b





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