Cementitious Grouts There are several types of cementitious grouts, the two most common classes in construction are Class A and Class C. Both classes are referred to as "non-shrink" however it is more accurate to say they are shrinkage compensated.
The main difference between the two is the expansion systems they contain to compensate for the shrinkage that would otherwise occur. Class A grout expands during the plastic state (i.e. uncured) and Class C grout expands in both the plastic and hardening stages. Both can achieve high strength when appropriately constrained during curing.
For precision structural grouting, usually Class C grouts are specified. They are more expensive relative to Class A.