What is Flexural Strength Test of concrete? explain in details with test procedure and examples.

The flexural strength test of concrete, also known as the “three-point bend test,” measures the ability of concrete to resist bending. This test is important for determining the overall strength and toughness of concrete, and is often used to assess the quality and consistency of a concrete mix.

Test Procedure:

1. Prepare a sample of concrete, either by cutting a piece from a concrete structure or by making a new sample.
2. Clean the surface of the concrete sample thoroughly to remove any dirt, oil, or other contaminants.
3. Place the concrete sample in a testing machine, and apply a load at the center of the sample through two loading points located at a specified distance apart.
4. Apply the load gradually and continuously, and record the load at the point of maximum deflection.
5. Repeat the test several times to obtain an average value for the flexural strength of the concrete sample.

The flexural strength of concrete is expressed in pounds per square inch (psi) or megapascals (MPa). The results of the flexural strength test are used to evaluate the overall strength and toughness of concrete, and to assess the quality and consistency of a concrete mix.

Examples:

1. For normal weight concrete, the flexural strength is typically in the range of 300-500 psi (2-3.5 MPa).
2. For high-performance concrete, the flexural strength is typically higher, in the range of 500-800 psi (3.5-5.5 MPa).
3. For lightweight concrete, the flexural strength is typically lower, in the range of 200-400 psi (1.5-2.5 MPa).

In conclusion, the flexural strength test is an important tool for engineers and contractors to evaluate the overall strength and toughness of concrete. The test provides valuable information about the quality and consistency of the concrete mix, and helps to ensure that the concrete meets the required standards and specifications for a particular application. The results of the flexural strength test can also be used to determine the most appropriate type of concrete for a particular project, and to ensure that the concrete will perform as expected over its expected service life.