Compression Test Action on Cube & Cylinder
|Fig.1: Cube Undergoing Compressive test|
The Compressive strength test will result in a compressive load on the cube and the cylinder during the test procedure. This process will result in the Lateral Expansion of the sample which will result in the Poisson’s ratio effect. The figure-1 below shows the compressive testing arrangement of a cube.
|Fig.2. Lateral Expansion in Cube during Compression Test|
The steel platens are placed above and below the specimen (cube/ cylinder) before the specimen is loaded. There no kind of lateral expansion carried out in the steel platens when compared to the concrete specimen. This means that the steel will restrain the tendency of concrete to expand in the lateral direction. This restrains for lateral expansion by the platen is shown in the concrete which is near to the end of the plate. The degree of restraining is depended on the friction that is actually developed.
Hence under normal conditions, an element within the specimen will undergo a combination of “shear stress”. This is because of the
- Friction between the platens and the specimen – Stress 1
- Compressive Load due to the loading action - Stress 2
It is observed that the combination of Stress 1 and Stress 2 will result in the axial load failure. This will result in providing a compressive strength value which is higher.
Concrete Cube and Cylinder Strength Relation
It has been observed that the restraining effect due to friction between the specimen and the platens extends over the entire height of the cube. But in the case of the cylinder, it remains unaffected. The activity is explained in the figure-3 and figure-4.
|Fig.3. Region Affected by Lateral Stresses in Cubes|
|Fig.4. Region Affected by Lateral Stresses in Cylinder|
Compressive Strength of cylinder = 0.8 x ( Compressive Strength of Cube )
Given the same concrete mix is used in both the samples