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Q: As per IS : 712 – 1984, the lime used for structural purposes (for making mortar and concrete for construction and foundation works) having an initial setting time of 2 hours (minimum) and final setting time of 48 hours (maximum) is :
  • A. Class D - Magnesium/Dolomitic lime
  • B. Class C - Fat lime
  • C. Class A - Eminently hydralic lime
  • D. Class F - Silicious Dolomitic lime
Correct Answer: Option C - As per IS 712-1984– Cl– 3.1 Building lime– Class A– Eminently hydraulic lime is used for making mortar and concrete for construction and foundation works, i.e. for structural purposes. Characteristics– (i) The colour is grey (ii) Calcium oxide and clay are 60-70 and 25 percent respectively. (iii) Sets and hardens reading under water with initial setting time 2 hour and final setting time 48 hours. (iv) Slakes with difficulty. Class B- Semi-hydraulic lime used for masonry mortars lime concrete and plaster undercoat. Class C- Fat lime used for finishing coat in plastering, white washing, composite mortar etc. Class D- Magnesium/dolomitic lime used for finishing coat in plastering, white washing. Class E- Kankar lime used for masonry mortars. Class F- Siliceous dolomitic lime used for undercoat and finishing coat of plaster.
C. As per IS 712-1984– Cl– 3.1 Building lime– Class A– Eminently hydraulic lime is used for making mortar and concrete for construction and foundation works, i.e. for structural purposes. Characteristics– (i) The colour is grey (ii) Calcium oxide and clay are 60-70 and 25 percent respectively. (iii) Sets and hardens reading under water with initial setting time 2 hour and final setting time 48 hours. (iv) Slakes with difficulty. Class B- Semi-hydraulic lime used for masonry mortars lime concrete and plaster undercoat. Class C- Fat lime used for finishing coat in plastering, white washing, composite mortar etc. Class D- Magnesium/dolomitic lime used for finishing coat in plastering, white washing. Class E- Kankar lime used for masonry mortars. Class F- Siliceous dolomitic lime used for undercoat and finishing coat of plaster.

Explanations:

As per IS 712-1984– Cl– 3.1 Building lime– Class A– Eminently hydraulic lime is used for making mortar and concrete for construction and foundation works, i.e. for structural purposes. Characteristics– (i) The colour is grey (ii) Calcium oxide and clay are 60-70 and 25 percent respectively. (iii) Sets and hardens reading under water with initial setting time 2 hour and final setting time 48 hours. (iv) Slakes with difficulty. Class B- Semi-hydraulic lime used for masonry mortars lime concrete and plaster undercoat. Class C- Fat lime used for finishing coat in plastering, white washing, composite mortar etc. Class D- Magnesium/dolomitic lime used for finishing coat in plastering, white washing. Class E- Kankar lime used for masonry mortars. Class F- Siliceous dolomitic lime used for undercoat and finishing coat of plaster.