Question

Surkhi is added to lime mortar to :

• A. Prevent shrinkage
• B. Increase bulk
• C. Decrease setting time
• D. Impact Hydraulicity

Hint:

Surkhi:
• Made from powdered burnt clay or brick dust
• Used with lime mortar
• Improves hydraulic properties and durability Hydraulic mortar can set even in moist conditions.

Answer 1

The Correct Option is D

Concept: Surkhi is a finely powdered material obtained from burnt clay, brick dust, or terracotta. It is commonly mixed with lime mortar to improve its engineering properties. Important effects of adding surkhi include:
• Improvement in hydraulic properties
• Better strength and durability
• Reduced shrinkage cracks The primary purpose is to impart hydraulicity to lime mortar.

Step 1: Analyze option A.
Surkhi may help reduce shrinkage, but this is not its primary purpose. Hence, option A is incorrect.

Step 2: Analyze option B.
Increasing bulk is not the main reason for adding surkhi. Hence, option B is incorrect.

Step 3: Analyze option C.
Surkhi does not mainly function to decrease setting time. Hence, option C is incorrect.

Step 4: Analyze option D.
Surkhi reacts with lime and helps develop hydraulic properties, enabling the mortar to set in damp conditions. \[ \text{Surkhi} + \text{Lime} \Rightarrow \text{Hydraulicity} \] Hence, option D is correct.

Step 5: Choose the correct option.
Surkhi is added to lime mortar to impart hydraulicity. Therefore, the correct answer is: \[ {\text{(D) Impact Hydraulicity}} \]