How is the flexural strength of concrete tested?

The flexural strength of concrete is primarily evaluated using the ASTM C78 test method, which measures the modulus of rupture. This test involves subjecting a concrete beam specimen to a bending force until failure occurs. The resulting load at which the specimen fails is used to calculate the flexural strength, which is a critical property for assessing how concrete will perform under load conditions that involve bending or flexural stresses.

This method is particularly relevant because it directly mimics the real-life scenarios where concrete structures experience bending forces, such as in beams, slabs, and pavements. By determining the modulus of rupture, engineers can ensure that the concrete mix design will meet the structural requirements and safety factors for the intended application.

The other choices relate to testing methods that assess different properties of concrete – compressive strength tests measure the ability of the material to withstand axial loads, while tensile tests and rebound hammer methods evaluate different aspects of concrete performance, not specifically addressing flexural strength.