Question

Statement (I): Fire resistance of plastering can be achieved by mixing surkhi to the cement mortar.

Statement (II): Insulation against sound and fire can be achieved by adding sufficient water in-situ just before applying the mortar. 

1. Both Statement (I) an Statement (II) are individually true and Statement (II) is the correct explanation of Statement (I) 
2. Both Statement (I) and Statement (II) are individually true but Statement (II) is not the correct explanation of Statement (I) 
3. Statement (I) is true but Statement (II) is false 
4. Statement (I) is false but Statement (II) is true 

Answer 1

Correct Answer - Option 3 : Statement (I) is true but Statement (II) is false 

Statement 1: True

Surkhi: Surkhi is finely powdered burnt clay and generally made from slightly under burnt bricks. Good surkhi should be perfectly clean and free from any impurities and should not contain particles retained on IS sieve No.9 more than 10% by weight.

Fire resistant mortar is prepared by adding 1 part of aluminous cement to 2 parts surkhi. This type of mortar is prepared by using fully surkhi instead of sand.

Statement 2: False

Insulation against sound and fire cannot be achieved by adding sufficient water in-situ just before applying the mortar. There are some identified materials which are used in mortar to get heat and acoustic insulation. Some of well-known products that are used for heat insulation are aerated concrete, gypsum boards, fibre boards, asbestos cement boards, chip boards, cork boards, foam plastic, fibre glass, glass wool etc.The commonly used sound insulating materials are cellular concrete, asbestos, rock wool, glass wool, glass silk etc.