Explain the relationship between compaction and concrete workability phenomenon

8 Factors that Affect the Workability of Fresh Concrete

Factors affecting the workability of concrete are materials such as water content, workable concrete as it can be easily mixed, transported, placed and compacted. Mix proportion of concrete tells us the ratio of fine aggregates and coarse. placing and compaction of concrete, which ultimately affects the properties of defined workability as the property of concrete which determines the amount aggregatelcement ratio, leaner the mix, hence lesser mobility because of . By now, you have seen that the workability of concrete is a complex phenomena and is. Workability is dependent on the proportion of the constituent material and on their Concrete Nominal Mix and Design Mix of Concrete: Know the Difference . particles & least amount of compacting efforts is required to compact the concrete . This phenomenon affects the flowability of concrete and due to fast hydration of.

Overall, this factor is only of secondary importance. Tips to Avoid or Reduce Segregation in Concrete Grading of aggregates has the greatest influence on workability.

The better the grading of aggregates, the less is the amount of void in concrete so well-graded aggregates should be used. When total voids are less in concrete, the excess paste is available to give better lubricating effect.

What are the Properties of Fresh Concrete?

Uses of Concrete Admixtures: This is one of the commonly used methods to enhance the workability of concrete. Concrete admixtures such as plasticizer and superplasticizers greatly improve the workability. This is called V-B time and gives a measure of compatibility of the concrete. This test is useful in determining the workability of concrete mixes with aggregates size up to 20 mm. It is expensive as compared to Slump Test and Compaction Factor Test and is used mostly in precast concrete works.

When concrete changes its state from fresh to hardened then this process is called setting. And the time required to complete this process is known as Setting Time of Cement.

Test on Fresh Concrete by Compaction Factor [Year - 3]

For increasing or decreasing the setting time Admixtures is used. The setting time for Portland cement is about 30 — 45 minutes. The separation of concrete ingredients from each other is known as segregation. This can be caused due to excessive vibration in concrete mixer machine or falling concrete from more than 1-meter height. This is the shrinkage that the fresh concrete undergoes untill it sets completely.

It may also be called initial shrinkage. This can be due to excessive loss of water from the concrete due to evaporation, bleeding, and soaking by formwork.

What are the Properties of Fresh Concrete?

Excessive shrinkage at initial stages may develop cracks. Therefore, all precautions should be taken to avoid excessive loss of water. This may be due to falling in temperature of concrete-mix from the time it laid to the time it sets completely.

An understanding and knowledge of the workability are the most important for making a well-designed concrete mix which can be easily placed and compacted with minimum effort.

Workability is a purely physical property of freshly mixed concrete. Workability of concrete simply means the ability to work with concrete.

Fresh concrete is said to be workable if it can be easily transported, placed, compacted, and finished without any segregation. The ease of placing, compacting, and finishing of concrete in the desired manner is called its workability. Concrete must be workable so that it achieves maximum density with a reasonable amount of compaction effort.

If concrete is not workable or relatively less workable, it will not be compacted to its desired density resulting in less strength and porosity ultimately.

If concrete is not workable, one will not be able to place it well. Adequate compaction of concrete is necessary; if it is not done properly there will be voids.