Why we use 150 mm size cube for compressive strength testing

Max size of aggregate to be used in concrete is 37.5 mm.
It's 4 times to the 37.5 mm.
37.5 x 4 = 150

Thus cube mould size is 150 mm
For 20 mm aggregate size concrete 100 mm cube mould size could be used.
 

Pravin Wakhure

Staff member
Sir,
Very well explained,
have a query w.r.t cube strength result for M30 after 28 Days we are obtained M45 result and Mix design is 270 Kg of cement and 110 Kg of GGBS / Per Cum for M30, can we reduce the cement content by 15 Kg to limit the over stengnth of cubes.
Please suggest
U would optimize the mix but before optimizing i would say check standard deviation as well as COV if these values are inline u may go for optimization by
considering thumb rule that for 1 MPA required 5 OPC suppose if u will get 5 MPA more than required then 5*5=25 kg but for factor of safety u would go for 50% i.e. 25/2=12.5 kg