Surkhi is a type of powdered brick that is added to lime mortar to improve its properties. The addition of surkhi to lime mortar imparts hydraulicity to the mixture, which means that it can set and harden underwater. This makes it an ideal material for use in construction projects that involve structures that will be in contact with water.

Why is surkhi added to lime mortar?

Surkhi is added to lime mortar for a number of reasons, including:

1. Imparting hydraulicity: Surkhi contains silica and alumina, which react with the lime to form compounds that can set and harden underwater. This makes the resulting mixture more durable and resistant to water damage.

2. Increasing strength: The addition of surkhi to lime mortar can increase its compressive strength, making it a stronger material overall.

3. Reducing shrinkage: Surkhi can help to reduce the amount of shrinkage that occurs as the lime mortar dries and sets. This can help prevent cracking and other damage to the structure.

4. Improving workability: Surkhi can improve the workability of lime mortar, making it easier to apply and shape.

5. Decreasing setting time: Surkhi can speed up the setting time of lime mortar, allowing it to be used more quickly.

Overall, the addition of surkhi to lime mortar can improve its properties and make it a more effective material for use in construction projects.