The cubes are generally tested at 7 & 28 days unless specific early tests are required, for example to remove a concrete shutter safely prior to 7 days. Usually 1 cube will be tested at 7 days and 2 cubes at 28 days, however this may vary depending of the requirements, check the design first. The cubes are removed from the curing tank, dried and grit removed. The cubes are tested using a calibrated compression machine. This can be carried out internally by competent personnel or by a certified test house.
The cubes are tested on the face perpendicular to the casting face. The concrete minimum compressive strength will be specified by the client/designer in a specific format.
Concrete Cube Weight
Unit weight (Density) of concrete=2400 Kg/cum
So we needed mass, i.e. formula is Mass=Density X volume
Volume of cube=150mm X 150mm X 150mm
Mass=2400 X (0.15*0.15*0.15) = 8.1
Weight of cube in kg = 8.1