Pick the correct statement:a)Angular of flaky particles reduce the workability and demand more cement and water to give the specified strength of concrete mixb)Angular of flaky particles produce a smoother mix for a given water/cement ratioc)Angular or flaky particles do not affect the workability of concreted)Angular of flaky particles produce a good mix instead of rounded particlesCorrect answer is option 'A'. Can you explain this answer?

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Explanation:

The correct statement is option 'A': Angular of flaky particles reduce the workability and demand more cement and water to give the specified strength of concrete mix.

There are several factors that affect the workability of concrete, and one of them is the shape of the particles used in the mix. The shape of the particles can be classified as either angular or rounded.

Angular particles:
- Angular particles have sharp corners and edges. They do not fit together well, leading to a higher void content in the mix.
- The higher void content reduces the workability of the concrete, making it more difficult to place and compact.
- Due to the irregular shape of the particles, they require more cement and water to fill the voids and achieve the desired strength of the concrete mix.
- The angular particles create a higher surface area, which increases the demand for cement paste to coat the particles, resulting in a higher cement content.

Rounded particles:
- Rounded particles have smooth surfaces and fit together more closely, resulting in a lower void content.
- The lower void content improves the workability of the concrete, making it easier to handle and place.
- The rounded particles require less cement and water to fill the voids and achieve the specified strength of the concrete mix.
- The smooth surface of the particles reduces the surface area, resulting in a lower demand for cement paste and a lower cement content.

Effects on workability:
- Angular particles with their irregular shape hinder the flow of the concrete, increasing the resistance encountered during placement and compaction.
- The lack of workability can make it more challenging to achieve proper consolidation and compaction, leading to potential defects in the finished concrete.

In conclusion, angular particles reduce the workability of the concrete mix, requiring more cement and water to achieve the desired strength. This is due to the higher void content and increased surface area of the angular particles, which negatively impact the flow and compactability of the mix.

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