Removing Humps and Hollows of a Uniform Concrete Surface

Introduction:
The operation of removing humps and hollows from a uniform concrete surface is an important step in the construction process. It ensures that the surface is smooth, even, and free from any irregularities. This operation is commonly performed in the construction industry and is essential for achieving a high-quality finished product.

Screeding:
The correct answer to the given question is option 'B', which is "Screeding." Screeding is a technique used to level and smooth the surface of freshly poured concrete. It involves the use of a screed, which is a long, straight board or a metal bar, to remove excess concrete and create a level surface.

Process:
The process of screeding involves the following steps:

1. Preparation: Before screeding, the concrete surface should be properly prepared. This includes removing any debris, cleaning the surface, and ensuring that it is properly moistened.

2. Placing the Screed: The screed is placed at one end of the concrete surface and is supported by two parallel guides or rails. The screed should be longer than the width of the area being screeded to ensure even distribution of the concrete.

3. Leveling the Surface: The screed is then pulled across the surface in a back-and-forth motion, with the leading edge slightly raised. This helps to remove excess concrete and fill any low spots, creating a smooth, even surface.

4. Checking for Levelness: During the screeding process, it is important to check for levelness using a level or a laser level. This ensures that the surface is uniform and free from humps and hollows.

5. Repeat if Necessary: If any areas are found to be uneven or have humps and hollows, the screeding process is repeated until a level surface is achieved.

Importance of Screeding:
Screeding is a crucial step in the concrete finishing process. It helps to:

- Create a smooth and even surface.
- Remove excess concrete and fill low spots.
- Ensure that the finished surface is level and free from humps and hollows.
- Provide a solid foundation for further finishing operations, such as trowelling or polishing.

Conclusion:
In conclusion, the operation of removing humps and hollows from a uniform concrete surface is known as screeding. It is an essential step in the construction process to achieve a high-quality finished product. Screeding involves the use of a screed to level and smooth the surface, ensuring that it is even and free from any irregularities.