Florida DOT Concrete Batchman/Operator Practice Exam

What should be included in the composition of concrete to achieve desired quality?

1. Only portland cement

2. Fine aggregate and cement only

3. Coarse aggregate and water only

4. A combination of aggregates and paste

The correct answer is: A combination of aggregates and paste

The inclusion of a combination of aggregates and paste in concrete composition is essential for achieving desired quality. The aggregates, which consist of both fine and coarse materials, provide the bulk and structural integrity to the concrete, while the paste, made of water and cement, binds the aggregates together and facilitates the chemical reactions necessary for setting and strength development. This balanced mix is crucial for various properties of concrete, such as durability, workability, and strength. Using only portland cement, fine aggregate, or coarse aggregate lacks the necessary components that contribute to a well-rounded concrete mixture. For example, solely using portland cement neglects the essential bulk provided by aggregates, which is vital for the overall structure. Similarly, relying only on fine aggregate and cement or coarse aggregate and water fails to create a cohesive mixture that meets engineering specifications and withstands environmental factors. Thus, a well-designed concrete mixture, incorporating both aggregates and paste, optimizes performance and meets the intended application requirements.