Uncertainty in Bogue-calculated phase composition of hydraulic cements

The Bogue calculations are used for cement manufacturing process control and acceptance limits for some cement classifications. While it is commonly understood that the Bogue calculations are estimates with potential intrinsic biases, the magnitudes of such biases are not generally known. The biases stem primarily from the compositional variation in phase solid solution, resulting in deviation of their bulk chemistry from that assumed in the calculations, and from bulk oxide measurement uncertainties. Uncertainties in Bogue estimates from these sources are quantified here through propagation-of-error analysis combining effects from bulk chemical analysis imprecision and estimates of variability in chemical compositions of the four principal clinker phases. Standard deviation (1σ) values of about 9.6% for alite and belite, and 2.2% and 1.4% for aluminate and ferrite are calculated. This significant increase compared to uncertainty due to bulk oxide measurements is attributable to the imprecision of the Bogue constants.