How to Find Compressive Strength of Concrete Cube
The compressive strength of concrete is a critical property that determines its ability to withstand loads without failure. It is an essential parameter in the design and construction of buildings, bridges, and other structures. In this article, we will discuss how to find the compressive strength of a concrete cube, a commonly used test method in the construction industry.
Understanding Compressive Strength
Compressive strength is the maximum load a material can bear before it fails under compression. In the case of concrete, this load is applied until the cube specimen cracks and breaks. The compressive strength of concrete is typically measured in megapascals (MPa) or pounds per square inch (psi). The higher the compressive strength, the stronger the concrete is considered to be.
Test Specimen Preparation
To determine the compressive strength of concrete, a standard size cube is commonly used. The cube should have dimensions of 150mm x 150mm x 150mm. The concrete mix should be prepared according to the design specifications and mixed thoroughly to ensure uniformity. The concrete is then poured into the cube mold and compacted using a vibrator to eliminate air voids.
Setting and Curing
After pouring the concrete into the mold, it is left to set for a certain period, usually 24 hours. Once set, the cube is removed from the mold and cured in water at a controlled temperature and humidity for a specified duration. The curing process is crucial as it allows the concrete to gain strength and develop its properties.
Testing the Compressive Strength
To test the compressive strength of the concrete cube, a universal testing machine (UTM) is used. The cube is placed horizontally in the UTM, and a compressive load is applied gradually until it fails. The load is applied at a rate of 0.5 to 1.0 MPa per second. The maximum load that the cube can withstand before failure is recorded as the compressive strength.
Calculating Compressive Strength
The compressive strength is calculated by dividing the maximum load by the cross-sectional area of the cube. The cross-sectional area is the product of the length and width of the cube, which is 150mm x 150mm. The formula for calculating compressive strength is:
Compressive Strength (MPa) = Maximum Load (kN) / Cross-sectional Area (mm²)
Interpreting Results
The compressive strength of concrete can be used to assess its quality and suitability for specific applications. Different design specifications require different levels of compressive strength. By comparing the obtained compressive strength to the required strength, engineers can determine if the concrete meets the design criteria.
In conclusion, determining the compressive strength of a concrete cube is a crucial step in ensuring the quality and safety of construction projects. By following the proper procedures for test specimen preparation, curing, and testing, engineers can accurately assess the strength of concrete and make informed decisions regarding its use in various applications.
