Typical Composition and Materials Properties

The average phase composition of Portland cement (ASTM Type I, CSA 10) is -50% alite, C3S -25% belite, P-C2S -12% tricalcium aluminate, C3A -8% ferrite, C4AF and -3.5% gypsum (Mindness, 1983). The structural order and crystallinity of the cement phases-and hence their hydraulic reactivities-are heavily dependent on the rate of cooling of the clinker  

Traditionally, the clinker composition is calculated from a chemical analysis of the clinker, using the time-honored Bogue equations (Bogue, 1929) and the very empirical relationships  

If some of the lime remains uncombined, it must be subtracted from the total Ume content before performing the calculation it is for this reason that a clinker analysis normally contains a value for uncombined free lime. It should also be stressed that the Bogue calculation does not give the true amounts of the four main clinker phases present, but differs from them principally because the actual mineral compositions differ from those assumed in the calculation, particularly 

1) Alite is defined as C3S with about 4% C3A in solid solution. 

2) Ferrite is not a true ternary phase but a (equimolecular. ) solid solution of C2A and C2F. 

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