In concrete testing, what does "F'c" represent?

"F'c" represents the specified compressive strength of concrete at 28 days, which is a key parameter in concrete testing and design. The compressive strength is a measure of how much force concrete can withstand before failing, and it's a crucial factor in determining the adequacy of concrete for structural applications.

Concrete is typically tested for compressive strength at 28 days because this is a standard period after mixing when the hydration process has largely stabilized, and concrete attains most of its strength. Testing at this age provides a reliable indicator of how the concrete will perform under load over time. Specifying F'c helps engineers and designers ensure that the concrete mix meets the structural requirements of a project.

The other options relate to different aspects of concrete properties but do not accurately describe "F'c." For example, maximum flexural strength pertains to resistance against bending, while tensile strength relates to resistance against pulling forces. Additionally, the weight of concrete per cubic meter is related to density rather than strength. Thus, understanding "F'c" as the specified compressive strength at 28 days is essential for proper concrete evaluation and application in construction.