w/c ratio is the ratio of
- AVolume of water to the volume of cement
- BVolume of water to the volume of concrete
- CMass of water to the mass of cementCorrect
- DMass of water to the mass of concrete
Solution
Concept
Water-cement ratio is the mass proportion of water to cement in a concrete mixture, fundamentally governing its compressive strength and workability.
Formula
w/c = Mass of Water / Mass of Cement
Step-by-step solution
1. Identify the components of the water-cement ratio: water and cement. 2. Note that mix proportions in concrete technology are standardly measured by weight (mass) rather than volume to ensure consistency and avoid errors due to bulking or compaction. 3. Therefore, w/c ratio = Mass of water / Mass of cement.
Explanation
The water-cement ratio (w/c ratio) is defined as the ratio of the mass (or weight) of mixing water to the mass of cement used in a concrete mix. It is the single most important parameter influencing the strength and durability of concrete, as established by Abrams' Law.
Why the other options are wrong
A: Volume ratio is not used because of bulking and air voids. B: Volume of concrete is not used in the denominator. D: Mass of concrete includes aggregates, not just cement.
Shortcut
Remember 'Mass over Mass' for concrete mix proportions (like w/c ratio).
Common mistake
Confusing mass/weight with volume. Although water can be measured in liters (which equals kg numerically), cement is always measured by weight in mix designs.
Correct answer: C) Mass of water to the mass of cement