Introduction:
The fineness of cement refers to the particle size distribution of the cement particles. It is an important property of cement as it affects the hydration and strength development of concrete. The fineness of cement is typically measured by the specific surface area, which is the total surface area of all the cement particles in a given mass of cement.

Explanation:
Increasing the fineness of cement has several effects on the properties of cement and concrete.

Influence on hydration:
When the fineness of cement is increased, it results in an increase in the rate of hydration. This is because the finer particles have a larger surface area, which allows for more contact with water. As a result, more water is consumed during the hydration process, leading to a faster reaction. The increased rate of hydration can be beneficial in situations where early strength development is desired.

Influence on heat of hydration:
The heat of hydration is the heat released during the chemical reaction between cement and water. When the fineness of cement is increased, it does not change the total amount of heat liberated during hydration. However, it can affect the rate at which heat is liberated. Finer particles have a larger surface area, which allows for faster reaction and heat generation. Therefore, increasing the fineness of cement can result in a higher rate of heat of hydration.

Summary:
In summary, increasing the fineness of cement results in an increase in the rate of hydration. This is because finer particles have a larger surface area, allowing for more contact with water and faster reaction. However, the increase in fineness does not change the total amount of heat liberated during hydration, but it can affect the rate of heat generation.