The addition of Fly-Ash as an additive in the brick mix proportions results in reduced drying shrinkage.

Explanation:
Fly-Ash is a by-product of coal combustion in thermal power plants. It is a fine powder that is rich in silica, alumina, and calcium oxide. Fly-Ash has been widely used as an additive in brick production due to its various beneficial properties.

Reduced Drying Shrinkage:
When Fly-Ash is added to the brick mix proportions, it helps to reduce the drying shrinkage of the bricks. Drying shrinkage refers to the reduction in volume that occurs when the moisture content of the brick decreases during the drying process. This shrinkage can lead to cracking and distortion of the bricks if it is excessive.

The addition of Fly-Ash helps to mitigate drying shrinkage in several ways:

1. Chemical Reaction: Fly-Ash reacts with calcium hydroxide (lime) present in the brick mix to form additional cementitious compounds such as calcium silicate hydrates and calcium aluminate hydrates. These compounds contribute to increased strength and reduced shrinkage.

2. Increased Fineness: Fly-Ash is a fine powder with a smaller particle size compared to the other components of the brick mix. This increased fineness allows for better packing of particles, resulting in a denser and more compact brick structure. A denser structure reduces the pore volume and restricts the movement of water, thereby reducing drying shrinkage.

3. Pozzolanic Activity: Fly-Ash exhibits pozzolanic activity, which means it can react with the calcium hydroxide in the presence of moisture to form cementitious compounds. This reaction helps to fill the microcracks and capillaries in the brick matrix, reducing the permeability and enhancing the durability of the bricks.

It is important to note that the addition of Fly-Ash in the brick mix proportions may have some trade-offs. For example, it may slightly reduce the compressive strength of the bricks. However, the benefits of reduced drying shrinkage, increased durability, and improved sustainability outweigh this minor reduction in strength.

In conclusion, the addition of Fly-Ash as an additive in the brick mix proportions results in reduced drying shrinkage. This is achieved through chemical reactions, increased fineness, and pozzolanic activity of Fly-Ash, which contribute to a denser brick structure and improved performance.