The composition of alite (tricalcium silicate) in a Portland cement clinker*

The composition of the alite (tricalcium silicate) phase in a Portland cement clinker has been determined by using an electron probe microanalyser. The molar proportions of the ions based on the unit cell are Ca 103·54 Fe 1·43, Mg 1·75, Na 0·80, K 0·18, Mn 0·02, Al 0·28 (in caldum sites); Al 0·23 (in interstitial sites); Si 34·48, Al 1·41, Ti 0·11 (in silicon sites); O 180. A comparison has been made with two other chemical analyses of tricaldum silicates and also with synthetic preparations.