Pick up the correct statement from the following: A: Free water = water added during mixing + surface water on aggregates. B: Total water = free water + water absorbed by aggregates.
Correct Answer: D. Both A and B
📚 Detailed Explanation: Free Water and Total Water in Mix Design
Why D (Both A and B) is correct: IS 10262 and standard mix design practice use these precise water definitions. Both statements are textbook-correct definitions used in the concrete mix design process.
Water Types in Concrete Mix Design
| Water Type | Definition | Role in Mix Design |
|---|---|---|
| Absorption water | Water inside pore structure of aggregate (not affecting the paste) | Subtracted from total water to get free water |
| Surface (film) water | Water coating outer surface of aggregate grains | Included in free water; reduces mixing water needed |
| Free water (effective) | Mixing water + surface water on aggregates | Directly affects w/c ratio and workability |
| Total water | Free water + absorbed water | Total water present in the mix |
Free water = Mixing water added + Surface water on aggregates
Total water = Free water + Water absorbed by aggregates
Total water = Free water + Water absorbed by aggregates
For mix design: w/c ratio uses FREE water (not total water)
- Statement A: correct definition of free water.
- Statement B: correct definition of total water.
- Both A and B are correct. The critical quantity for strength (w/c ratio) uses FREE water.