Cube Strength Of Concrete:
The strength achieved by the concrete on 15 cm concrete cubes after curing of a temperature of 27± 2° C is known as cube strength of concrete. Curing water should be replaced at an interval of 7 days. The sample is not permitted to dry before testing. Cubes are submerged in water after preparation of 24 hours, they should be kept in such a place where the minimum relative humidity is 90%.
At the point when cubes are produced at the field site, they are known as works cube and the strength of these cubes are known as works cube strength.
These days concrete mixes are not categorized by the proportion of concrete ingredients but rather by the cube strength after testing for 28 days concrete curing. For example, M100, M150, M200 have cube strength of 100, 150, 200 kg/cm2 after curing of 28 days.
As per most recent ISI unit of force has been changed from kg to Newton. N(0) subsequently plain concretes are classified M10, M15, M20, M25 where M refers to the mix and 10, 15, 20, 25 represents the cube strength of concrete in N/mm2 after curing of 28 days in field condition.