The overall Strength of a structure such as flexural resistance and abrasion directly depends upon the compressive strength of concrete. Cube test is basically done to know the Compressive Strength of concrete which is the Characteristic strength of a 150mm size concrete cube tested at 7 & 28 days.Concrete gains its strength rapidly till 7th & 14th Days. Then gradually increases from there.

For cube test ,two types of specimensof 15cm X 15cm X 15cm size are used. Concrete is poured in the mould and tempered properly so as not to have any voids. After 24 hours these moulds are removed and test specimens are put in water for curing. These specimens are tested by compression testing machine after 7 days curing or 28 days curing. Load should be applied gradually at the rate of 140 kg/cm2 per minute till the Specimens fails. Load at the failure divided by area of specimen gives the compressive strength of concrete.

Compressive Strength of concrete = Maximum compressive load / Cross Sectional Area.
The obtained strength has to confirm to the standards fixed.