What characteristic of concrete is measured by its compressive strength?

The characteristic of concrete that is measured by its compressive strength is its ability to withstand axial loading. Compressive strength is defined as the maximum amount of compressive stress that a material can withstand before failure occurs. In the context of concrete, this means how well the material can support loads that compress its structure, such as vertical loads from building components or other structures.

This measurement is vital in construction and engineering because it helps determine whether a particular mix of concrete can hold the required loads during its service life without failing. In contrast, tension forces primarily relate to tensile strength, which is a different property of concrete and is not typically measured in standard compressive strength tests.

Similarly, flexibility refers to how much a material can bend without breaking, which is not a primary characteristic of concrete as it tends to be more brittle. Lastly, permeability pertains to how well fluids can pass through the concrete, another important property but unrelated to compressive strength directly. Thus, the compressive strength specifically relates to the ability of concrete to withstand axial loads effectively.