Answer:

The process of adding a finely ground, fully hydrated Portland cement to the fresh concrete in order to make high strength concrete is called seeding.

Seeding is a technique used in concrete construction to improve the strength and durability of the concrete mixture. It involves adding additional cement to the fresh concrete mix to enhance its properties.

Importance of Seeding:

Seeding is primarily used to increase the strength of concrete. By adding finely ground, fully hydrated Portland cement to the mix, the overall cementitious content is increased. This leads to a higher density and a stronger concrete matrix.

Seeding also helps in improving the durability of the concrete. The additional cement particles act as nucleation sites for the hydration process, resulting in a more complete and uniform hydration of the cement particles. This reduces the chances of voids and weak spots in the concrete, making it more resistant to cracking, abrasion, and chemical attack.

The Process of Seeding:

1. Prepare the fresh concrete mix: The initial concrete mix is prepared by combining cement, aggregates, water, and other additives. The mix should be properly proportioned to achieve the desired strength and workability.

2. Determine the seed dosage: The amount of additional cement to be added as seed is determined based on the desired strength and the characteristics of the original mix. The seed dosage is typically expressed as a percentage of the weight of the original cement.

3. Finely grind the seed cement: The additional cement is finely ground to increase its reactivity and ensure a thorough mixing with the fresh concrete. This can be done using a ball mill or other grinding equipment.

4. Add the seed cement to the mix: The finely ground seed cement is added to the fresh concrete mix during or after the initial mixing process. It is important to ensure proper distribution of the seed particles throughout the mix to achieve uniform strength enhancement.

5. Mix thoroughly: The seeded concrete mix is then mixed thoroughly to ensure proper dispersion of the seed particles. This can be done using traditional mixing techniques or specialized equipment such as high-speed slurry mixers.

6. Place and cure the concrete: The seeded concrete is then placed in the desired location and cured properly to allow for the hydration of the cement particles. This includes providing adequate moisture, temperature control, and curing duration.

By following the process of seeding, high strength concrete can be achieved, which is essential in many construction applications where structural integrity and durability are of prime importance.