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concrete workability

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Concrete workability refers to the ease with which concrete can be mixed, placed, and compacted while maintaining uniformity and homogeneity. Several factors influence concrete workability, including water-cement ratio, aggregate properties, and the use of admixtures.






Factors affecting workability 

1. Water-Cement Ratio (W/C):
    • Increasing the water-cement ratio improves workability but reduces the strength of the concrete mix.
    • A higher W/C ratio also increases permeability, compromising durability and strength.
    • Conversely, using too little water may result in incomplete cement hydration, leading to a loss of strength.
    • The typical W/C ratio ranges from 0.35 to 0.40.
2. Aggregate Size:
    • Larger aggregates have a smaller total surface area, requiring less water for wetting, which improves workability at the same water content.
3. Aggregate Shape:
    • Aggregates with elongated or flaky shapes reduce workability compared to rounded or cubical aggregates.
4. Aggregate Grading:
    • Well-graded aggregates improve workability by reducing voids in the mix, allowing excess paste to enhance lubrication.
5. Use of Admixtures:
    • Chemical admixtures, such as superplasticizers, increase workability while reducing the required W/C ratio, improving both flowability and strength.

Methods to Measure Concrete Workability

Concrete workability is typically assessed using the following tests:

Field Considerations

In ready-mix concrete, increasing workability by adding water on-site is strictly prohibited because it increases permeability, ultimately reducing both strength and durability. Instead, workability should be adjusted using proper mix design and admixtures.



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