Explanation:

Frog is a depression provided in the face of a brick during its manufacturing process. It is used to provide a better grip to the mortar and to increase the bond strength between bricks. Let's understand why the frog of the brick masonry is generally kept on the top face.

- Top face: The top face of the brick is the one that is exposed to the environment and is visible after the construction of the wall. Therefore, it is important to ensure that the top face of the brick is smooth and aesthetically pleasing. By keeping the frog on the top face, the rough surface of the frog is hidden, and the top face of the brick remains smooth.

- Grip to the mortar: The purpose of the frog is to provide a better grip to the mortar. By keeping the frog on the top face, the weight of the brick compresses the mortar into the frog, which provides a strong bond between the brick and the mortar.

- Water absorption: The frog also helps in reducing the water absorption capacity of the brick. If the frog is kept on the bottom face, it can increase the water absorption capacity of the brick and may lead to structural issues in the long run.

- Standardization: Generally, the frog of the brick is kept on the top face to maintain standardization in the construction industry. It helps in easy identification of the bricks and ensures that the bricks are used in the correct orientation.

Conclusion:

To summarize, the frog of the brick masonry is generally kept on the top face to provide a better grip to the mortar, reduce water absorption, maintain standardization, and ensure that the top face of the brick remains smooth and aesthetically pleasing.