Workability of Concrete

The workability of concrete refers to its ease of being mixed, placed, and compacted. It is an important property of concrete as it affects the ease of construction and the final quality of the concrete structure. Workability is influenced by various factors such as water-cement ratio, aggregate shape and size, admixtures, and the characteristics of the cement paste.

Workability and Time

The workability of concrete generally reduces with time. This means that as time passes after the concrete is mixed, it becomes less fluid and more difficult to handle. There are several reasons for this:

1. Hydration: Concrete undergoes a chemical reaction called hydration, where the cement particles react with water to form a solid mass. As hydration progresses, the concrete gradually sets and hardens, resulting in a decrease in workability.

2. Water Evaporation: During the early stages of concrete placement, water evaporates from the surface of the concrete, causing it to lose moisture. This loss of moisture leads to a decrease in workability, making the concrete stiffer and less workable.

3. Lubrication: Workability is also influenced by the lubricating effect of water in the concrete mix. As time passes, the water in the mix gets absorbed by the cement particles, reducing the lubricating effect. This results in increased friction between the particles, making the mix less workable.

4. Chemical Reactions: Some chemical reactions can occur over time in the concrete mix, leading to changes in its properties. These reactions can cause the formation of compounds that reduce the workability of the concrete.

Conclusion

In conclusion, the statement "Workability reduces with time" is true. The workability of concrete generally decreases as time passes due to factors such as hydration, water evaporation, loss of lubrication, and chemical reactions. It is important for construction workers to consider the time of concrete placement and ensure that the mix is properly managed to maintain the desired workability for the construction process.