Basically, in the pile foundation, we use M20 to M40 concrete grade.
Pile foundation should have higher cover to protect deterioration from the surrounding soil.
Various type of pile has various specification, and as per specification, we should provide a concrete grade.
Concrete grade and steel grade and steel arrangement are totally depend on design philosophy.
We can also use various types of cement-like super sulfate cement, pozzolanic cement, sulfate resisting cement, other special kinds of cement, maybe use.