Building Materials, Third Edition

€—— PRQ

3. When combined with cement which of the following constituents of puzzolana combine
   with free lime released during the hydration of cement?
   (a) SiO 2 (b) Al 2 O 3
   (c) Fe 2 O 3 (d) MgO


4. The best application of puzzolana in cement concrete is in
   (a) dams (b) bridges
   (c) RCC slabs (d) domes


5. Consider the following statements with regards to fly ash to be used for making concrete
   
   
   1. The carbon content should be as low as possible
   
   
   2. The fineness of fly ash should be as high as possible
   
   
   3. The silica in fly ash should be in finely divided state
      Of the above statements
      (a) only 1 is correct (b) 1, 2 are correct
      (c) 1, 2, 3 are correct (d) 2, 3 are correct
   
   
   
   


6. Surkhi is added to lime mortar to
   (a) prevent shrinkage (b) decrease setting time
   (c) increase bulk (d) impart hydraulicity


7. Blast furnace slag has approximately
   (a) 45% calcium oxide and about 35% silica
   (b) 50% alumina and 20% calcium oxide
   (c) 25% magnesia and 15% silica
   (d) 25% calcium sulphate and 15% alumina


8. Consider the following statements:
   Puzzolana used as an admixture in concrete has the following advantages:
   
   
   1. It improves workability with lesser amount of water
   
   
   2. It increases heat of hydration and so sets the concrete quickly
   
   
   3. It increases resistance to attack by salts and sulphates
   
   
   4. It leaches calcium hydroxide
      Select the correct answer using the codes given below:
      Codes:
      (a) 1, 2, 3 and 4 (b) 1, 2 and 4
      (c) 1 and 3 (d) 2, 3 and 4
   
   
   
   

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1. (d) 2. (c) 3. (a) 4. (a) 5. (c) 6. (d) 7. (a) 8. (c)