What is Compressive Strength Test? explain in details with test procedure and examples.

The compressive strength test is a fundamental test that measures the ability of concrete to resist compressive stress and crushing forces. The test is performed by applying a compressive load to cylindrical or cubic concrete specimens, typically with a diameter of 150mm and a height of 300mm, until they fail.

Test Procedure:

1. Obtain cylindrical or cubic concrete specimens of a standard size, typically with a diameter of 150mm and a height of 300mm.
2. Allow the specimens to cure for a specified period of time, typically 7, 14, or 28 days, in a controlled environment at a temperature of 20°C to 25°C and a relative humidity of 50%.
3. Place the concrete specimens in compression testing machine, ensuring that they are properly aligned and centered.
4. Apply a compressive load to the specimens, at a constant rate of deformation, until they fail.
5. Record the maximum compressive load reached before failure, and calculate the compressive strength of the concrete using the formula: compressive strength = maximum load/cross-sectional area of the specimen.

The compressive strength of concrete is typically expressed in megapascals (MPa) or pounds per square inch (psi), and is considered to be one of the most important properties of concrete. The compressive strength of concrete can be used to evaluate its quality, predict its behavior under stress, and compare it to the design strength specified for a particular application.

Examples:

1. For residential construction, the compressive strength of concrete is typically in the range of 20 to 40 MPa (2,900 to 5,800 psi).
2. For commercial and industrial construction, the compressive strength of concrete may be higher, typically in the range of 40 to 80 MPa (5,800 to 11,600 psi).
3. For high-performance or high-strength concrete, the compressive strength may be even higher, typically in the range of 80 to 100 MPa (11,600 to 14,500 psi) or higher.

In conclusion, the compressive strength test is a critical test that provides important information about the quality, strength, and performance of concrete, and is an essential tool for engineers and contractors to ensure that concrete meets the required standards and specifications for a particular application.