Civil Engineering - Concrete Technology - Discussion

A concrete using an air-entrained cement exhibits the following characteristics:

*Has more resistance to weathering:* This is a primary benefit. The entrained air voids provide space for water to expand upon freezing, reducing internal pressure and damage from freeze-thaw cycles.
*Is more plastic and workable:* The air bubbles act as a sort of lubricant, improving the workability of the fresh concrete.
*Is free from segregation and bleeding:* The air bubbles help to hold the mix together, reducing the tendency for the aggregates to separate (segregation) and for water to rise to the surface (bleeding).

However, it's important to note that air entrainment typically *has a strength of less than 10% to 15%* compared to non-air-entrained concrete.
The introduction of air voids reduces the overall density of the concrete, which can slightly decrease its compressive strength.

Therefore, the most accurate answer considering all the options is **all the above**.

Segregation and bleeding does not depend on the type of cement so option E is not correct. Furthermore it should also be clear that if concrete has voids than it has no good resistance to weathering agents.

If air entrained cement is used then the water-cement ratio also increases which causes segregation and bleeding in concrete. So option C is correct.

As, basic purpose of air entraining agent is to make concrete more durable and workable, option C is correct.

Air entrainment in concrete reduces bleeding and segregation, increasing workability.

If air entrained in cement then concrete is losses it's strength upto 10-15 %.

Strength decreases up to 5° per 1% by volume air entrainment.

It should be E but in Arora also option C is given.

The correct answer should be option E.

The correct answer is E. I too agree.