The four-point flexural test provides values for the modulus of elasticity in bending ${\displaystyle E_{f}}$, flexural stress ${\displaystyle \sigma _{f}}$, flexural strain ${\displaystyle \varepsilon _{f}}$ and the flexural stress-strain response of the material. This test is very similar to the three-point bending flexural test. The major difference being that with the addition of a fourth bearing the portion of the beam between the two loading points is put under maximum stress, as opposed to only the material right under the central bearing in the case of three-point bending.

This difference is of prime importance when studying brittle materials, where the number and severity of flaws exposed to the maximum stress is directly related to the flexural strength and crack initiation. Compared to the three-point bending flexural test, there are no shear forces in the four-point bending flexural test in the area between the two loading pins. The four-point bending test is therefore particularly suitable for brittle materials that cannot withstand shear stresses very well.

It is one of the most widely used apparatus to characterize fatigue and flexural stiffness of asphalt mixtures.

The test method for conducting the test usually involves a specified test fixture on a universal testing machine. Details of the test preparation, conditioning, and conduct affect the test results. The sample is placed on two supporting pins a set distance apart and two loading pins placed at an equal distance around the center. These two loadings are lowered from above at a constant rate until sample failure.

Calculation of the flexural stress ${\displaystyle \sigma _{f}}$

in these formulas the following parameters are used:

Advantages of three-point and four-point bending tests over uniaxial tensile tests include:

Disadvantages include: