A cube test procedure for Compressive strength of concrete

Concrete has high compressive strength but lower tensile strength. Concrete is the major material in all types of residential and commercial building constructions. Its strength influences the construction work to a great extent. Its strength is derived from the binding power of cement with sand. According to the Manager Sangal Construction, the constructioncompanies in North India, the test is commonly performed several times at different levels of construction during each project. 

 

What is compressive strength of concrete?

The compressive strength of a material or structure is to withstand force under compression. It is an ability of a material to resist failure in the form of cracks and fissure. In this test, the push force is applied on both ends of a block of concrete and the maximum compression that it bears without failure is recorded. In technical language, we can say that compression strength of concrete is defined as the characteristic strength of 150 mm concrete cube after 28 days. Concrete is a mixture of different portions of sand, cement, and aggregate. The strength of concrete depends on several factors such as quality of cement & sand, water-cement ratio, and curing methods and treatment effects. To get desired results, the test is generally performed.

Why compressive strength of concrete measurement is necessary?

The premature removal of framework or lifting live support from large construction may cause cracking or other damage to it. To avoid damage to a structure, it is necessary to measure the strength of the concrete to ensure its strength.

Why do compressive tests done for 7/ 14 or 28 days?

The concrete generally attains maximum strength in 28 days. The strength is also tested for 7days and 14 days to predict the targeted strength of a structure.  On an average, the 14 days concrete shows 90% of the target strength. Its strength slows down after 14 days and it takes 28 days to achieve 99% of strength. It is required to get at least 3 specimens of the testing and the mean compressive strength is used to determine the actual strength of the batch. The cube block of concrete is placed under water after its proper set in 24 hours. The test specimen is kept submerged in water for 7 or 14 or 28 days while changing the water after 7 days.

To test the strength, the cube is placed, while aligned properly, between the plates of a testing machine. The load is increased at the rate of 140kg/sq cm/min till the cube does collapse. As the specimen starts cracking, the reading of the pressure is noted according to the residentialbuilders in Haryana who offers construction of homes, villas, and hostel in the state.

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