The composition and manufacturing conditions have relatively little influence on the grindibility of cement clinker.
The clinker melt which set as a glass with rapid clinker cooling is significantly harder to grind than microstructure consisting of finely crystalline tricalcium aluminate and calcium aluminoferrite produced during more gradual cooling tricalcium silicate and free CaO are easier to grind than dicalcium silicate; as a result the tricalcium silicate and free lime accumulate in the finest fraction and dicalcium silicate in the coarse fraction of the ground clinker.
The silicate are also easier to grind if the clinker has been cooling rapidly. From the point of view of grindibility as well as of clinker quality it is therefore appropriate for the clinker to be cooled slowly down to a temperature of 1250 OC and than rapidly. The method of burning has no significant influence on the grindibility, although clinker with many pores is easier to grind than clinker with few pores.
This effect is likely to be more apparent with lower finenesses than with higher finenesses
(Source : Cement Principle of production and use by Friedrich W. Locher page 118 (Verlag Bau Technik))