Building Material Questions (BM9)

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



  1. Select the incorrect statement.


    1. Fly ash reduces permeability
    2. Curing period for fly ash concrete is less.
    3. Fly ash increases density of concrete
    4. Fly ash decreases expansion due to alkali-aggregate reaction

    View Answer
    Answer: b
    Curing period of fly ash concrete should be longer as pozzolanic reaction can only proceed in the presence of water. Enough water should be available for a long time.

  2. The use of ground granulated blast furnace slag in concrete increases ...


    1. heat of hydration
    2. permeability
    3. resistance to corrosion of reinforcement bars
    4. cement content

    View Answer
    Answer: c
    It reduces the heat of hydration, cement content and permeability and increases resistance to chemical attack and corrosion of reinforcement bars and improves workability and strength.

  3. Which of the following is correct?


    1. Rich concrete increases workability
    2. Angular aggregate increases workability
    3. Small aggregates will give higher workability
    4. All are correct

    View Answer
    Answer: a
    Rich concrete means lower aggregate/cement ratio, hence less matrix will be required to lubricate the aggregate.
    Round aggregate increases workability
    Small aggregate will have high surface area and hence more amount of matrix will be required to lubricate the aggregate.

  4. The dimensions (bottom diameter, top diameter and height) of a slump cone are ... mm


    1. 200,150,300
    2. 300,200,300
    3. 200,100,400
    4. 200,100,300

    View Answer
    Answer: d
    As per IS 1199, the dimensions of bottom diameter, top diameter and height of a slump cone are 200,100 and 300 mm respectively.

  5. When concrete subsides from only one side in a slump test then the slump is called ...


    1. True slump
    2. Shear slump
    3. Collapse slump
    4. Zero slump

    View Answer
    Answer: b

  6. In how many layers a slump cone is filled?


    1. 2
    2. 3
    3. 4
    4. 5

    View Answer
    Answer: c
    As per IS 1199, a slump cone is filled by 4 layers of concrete.

  7. Segregation of concrete is ...


    1. Separation of coarse aggregate from rest of the ingredients of concrete
    2. Separation of cement matrix from rest of the ingredients of concrete
    3. Both (a) and (b)
    4. None of the above

    View Answer
    Answer: a
    Option (b) is correct for bleeding.

  8. Bleeding in concrete is caused due to ...


    1. highly wet mix
    2. badly proportioned mix
    3. insufficiently mixed concrete
    4. All of the above

    View Answer
    Answer: d

  9. How much extra cement is added when hand mixing is done?


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

    View Answer
    Answer: b

  10. Which of the following is never measured in volume?


    1. Aggregates
    2. Cement
    3. Water
    4. None of the above

    View Answer
    Answer: b






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