Red Seal Concrete Finisher Practice Exam

Which factor is essential for determining the final strength of concrete?

1. The size of the aggregates used

2. The water-to-cement ratio

3. The color of the concrete

4. The type of curing compound applied

The correct answer is: The water-to-cement ratio

The water-to-cement ratio is a crucial factor in determining the final strength of concrete because it directly affects the hydration process of the cement. When water is mixed with cement, a chemical reaction occurs that allows the mixture to harden and gain strength as it cures. If the ratio of water to cement is too high, it can lead to a weaker mix due to excessive porosity, which creates air pockets and reduces the amount of cement that can bond with the aggregates. Conversely, a lower water-to-cement ratio typically results in higher strength and durability, as it fosters a denser concrete structure. The size of the aggregates can influence the workability and strength of concrete, but it is the water-to-cement ratio that plays the primary role in determining the overall strength. The color of the concrete is largely aesthetic and does not impact structural strength. The type of curing compound, while important for maintaining moisture during curing, does not affect the inherent strength produced from the water-to-cement ratio during the initial hydration and hardening phases of concrete.