General Contractor Practice Exam

What is the standard concrete mix formula for a basic concrete mix?

1. 1 part cement, 3 parts sand, 2 parts gravel

2. 1 part cement, 2 parts sand, 4 parts gravel

3. 1 part cement, 1 part sand, 5 parts gravel

4. 2 parts cement, 2 parts sand, 3 parts gravel

The correct answer is: 1 part cement, 2 parts sand, 4 parts gravel

The standard concrete mix formula for a basic concrete mix typically follows a ratio of 1 part cement, 2 parts sand, and 4 parts gravel. This mix is known as the 1:2:4 ratio, which provides a strong and workable concrete that is suitable for general construction purposes. In this mix, the cement acts as a binding agent that holds the other materials together when the concrete sets. The sand fills the spaces between the larger particles of gravel, helping to create a dense mixture. Gravel provides the bulk and structural strength that contributes to the overall durability of the concrete. This ratio is recognized as a balance between workability and strength, making it a widely adopted standard for basic concrete applications. In contrast, the other options could lead to variations in the strength and workability of the concrete. For example, using too much sand, as suggested in some alternatives, could lead to a mix that is too weak or may not set properly, while too much gravel might create a mix that is difficult to work with and could compromise the structural integrity. Thus, the 1:2:4 mix is regarded as the most effective and standardized approach for basic concrete formulations.