M5, M10,used for P.C.C and now a days M15 grade of concrete
has been widely used for PCC.
Where as M20,M25 used for footings,columns,beams&slabs.
From M30 grade of concrete onwards it is Design Mix
Is there a necessity for providing expansion joints in long
RCC structure(say a wall of a water retaining structure)-
say approximately 50 metres in length and about 4 metres
high? What will be the limitations?