Building Material Questions (BM7)

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

1. If the angularity number is ZERO, what will be the percentage of the solid volume of the aggregate?

   
   

   1. 44
   2. 56
   3. 67
   4. None of the above

   View Answer

   Answer: c
   The aggregates which are suitable for making the concrete may have angularity number from ZERO to 11. Determination of Angularity Number is done as per IS 2386 part 1:1963



2. Which of the following expression is correct?

   
   

   1. ${f}_{A}=\frac{3\times {f}_{H}}{20}+1.0$
   2. ${f}_{H}=\frac{3\times {f}_{A}}{20}+1.0$
   3. ${f}_{A}=\frac{6\times {f}_{H}}{20}+1.0$
   4. None of the above

   
   Where, ${f}_{A}=\text{Angularity Index}$
   ${f}_{H}=\text{Angularity Number}$

   
   
   View Answer

   Answer: a The expression was suggested by Murdock



3. Which of the following is the formula to calculate angularity number?

   
   

   1. $67-\frac{100\times{C}}{W \times{G}}$
   2. $67-\frac{100\times{W}}{C \times{G}}$
   3. $67-\frac{C}{100\times {W} \times{G}}$
   4. None of the above

   
   Where, ${C}=\text{Weight of water, gram}$
   ${W}=\text{Mean weight of aggregate, gram}$
   ${G}=\text{Specific Gravity of Aggregate}$

   
   
   View Answer

   Answer: b
   This expression is given in IS: 2386-Part 1: 1963



4. Which of the following aggregate has granular texture?

   
   

   1. Slate
   2. Sandstone
   3. Granite
   4. Dolerite

   View Answer

   Answer: b
   Slate has a smooth texture
   Granite and Dolerite have crystalline texture.



5. How will the properties of concrete get affected if fine or coarse aggregates contains an excessive amount of silt and clay?

   
   

   1. Shrinkage will increase
   2. Permeability will increase
   3. Poor bond
   4. All of the above

   View Answer

   Answer: d



6. Colorimetric Test is performed to determine the level of which of the following impurities in aggregates?

   
   

   1. Organic impurities
   2. Silt and clay
   3. Salts
   4. Iron Pyrites

   View Answer

   Answer: a



7. What is the average percentage loss of weight in aggregates after 10 cycles when Magnesium sulphate is used?

   
   

   1. 12
   2. 18
   3. 24
   4. 28

   View Answer

   Answer: b



8. What is the ideal temperature range for an alkali-aggregate reaction?

   
   

   1. $10-38^\circ C$
   2. $12-45^\circ C$
   3. $16-30^\circ C$
   4. $20-40^\circ C$

   View Answer

   Answer: a



9. Which of the following sieves is not used in sieve analysis?

   
   

   1. 63 mm
   2. 50 mm
   3. 15 mm
   4. 2.36 mm

   View Answer

   Answer: c
   As per IS:2386 Part 1:1963, following sieves are used in sieve analysis:
   63, 50, 40 or 31.5, 25, 20 or 16, 12.5, 10, 6.3, 4.75 and 2.36. [All are in mm]



10. If the Fineness Modulus of sand is greater than 3.2, it will be ______ for making satisfactory concrete.

    
    

    1. Perfect
    2. Suitable
    3. Unsuitable
    4. Can not say

    View Answer

    Answer: c



11. If the Fineness Modulus is 2.5, the sand is classified as

    
    

    1. Fine Sand
    2. Medium Sand
    3. Coarse Sand
    4. None of the above

    View Answer

    Answer: a
    Fine Sand - 2.2 - 2.6
    Medium Sand - 2.6 - 2.9
    Coarse Sand - 2.9 - 3.2



12. Fine aggregate is divided into ____ grading zones.

    
    

    1. 3
    2. 4
    3. 5
    4. 6

    View Answer

    Answer: b
    As per IS: 383: 2016 Fine aggregates are divided into 4 grading zones.



13. The Elongation index is not applicable to sizes smaller than _____.

    
    

    1. 5.5 mm
    2. 6.3 mm
    3. 7.3 mm
    4. None of the above

    View Answer

    Answer: b
    Both Flakiness Index and Elongation Index are not applicable to sizes smaller than 6.3 mm.



14. To perform the crushing test on aggregates, aggregates are

    
    

    1. Passed through 10 mm sieve and retained on 4.75 mm sieve
    2. Passed through 12.5 mm sieve and retained on 10 mm sieve
    3. Passed through 20 mm sieve and retained on 16 mm sieve
    4. Passed through 16 mm sieve and retained on 12.5 mm sieve

    View Answer

    Answer: b
    This test is performed as per IS: 2386 Part 4: 1963



15. When aggregates are to be used in building construction, crushing value should not exceed _____ percent.

    
    

    1. 30
    2. 35
    3. 40
    4. 45

    View Answer

    Answer: d
    30% for aggregates to be used in wearing surfaces.

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