How is the compressive strength of concrete typically measured?

The compressive strength of concrete is measured by crushing concrete cylinders in a controlled laboratory environment. This process involves casting concrete into cylindrical molds and allowing it to cure for a specified period, typically 28 days. After this curing period, the cylinders are subjected to an axial load until failure occurs. The maximum load sustained by the cylinder just before it fails is recorded, and this value is then used to calculate the compressive strength by dividing the load by the cross-sectional area of the cylinder.

This method is preferred because it provides an accurate and standardized measurement of the concrete’s strength, which is crucial for ensuring that structural elements meet design specifications and safety requirements. The other options, such as tensile testing of steel reinforcement or conducting a water absorption test, do not directly measure the compressive strength of concrete. Visual inspection may provide insights into surface conditions but cannot assess the internal strength of the concrete accurately. Thus, crushing concrete cylinders is the established and reliable method for assessing compressive strength.