What is water cement ratio?

• A. The weight ratio of water to cement in a concrete mix (expressed as a decimal or percentage)
• B. The ratio of cement to water to aggregate
• C. The ratio of water to cement by volume
• D. The ratio of cement to water per surface area

Answer: (A)

The water-cement ratio is the weight of water divided by the weight of cement in a concrete mix. It’s usually written as a decimal (for example, 0.45) or as a percentage (45%). This ratio matters because water hydrates the cement to form the binding matrix, but excess water creates voids that weaken the concrete. A lower ratio tends to produce stronger, more durable concrete with less porosity, but can make the mix harder to place and finish. A higher ratio improves workability but reduces strength and durability due to more voids. This definition focuses on the relationship between water and cement by weight, not involving aggregates or volumes, and it is the standard way to express the mix design.