For a concrete mix design, an estimation of water content corresponds to
- Aoven-dried aggregates
- Bsaturated surface dry aggregatesCorrect
- Cair-dried aggregates
- Dwet aggregates
Solution
Concept
Aggregate moisture condition in mix design
Step-by-step solution
1. Mix design tables (IS 10262) give water content for aggregates in the saturated surface dry (SSD) condition. 2. Corrections are then made for the actual moisture condition at site.
Explanation
In the SSD state the aggregate neither absorbs water from nor gives water to the mix, so the water–cement ratio is not changed by aggregate moisture. Mix proportions are therefore calculated on the SSD basis.
Why the other options are wrong
Oven-dry, air-dry and wet aggregates would take up or release water and change the effective water–cement ratio.
Shortcut
Mix design = SSD aggregates.
Common mistake
Choosing oven-dried aggregates.
Correct answer: B) saturated surface dry aggregates