Identifying Improved Standardized Tests for Measuring Cement Particle Size and Surface Area

The Blaine fineness (Blaine) of a cement powder is a single parameter that is meant to characterize the specific surface area of a cement; Blaine is assumed to be linked to physical and mechanical properties of the hydrated cement such as strength, setting time, and rheology. However, a single parameter cannot characterize the particle-size distribution of a cement powder, on which the hydration kinetics and solid properties depend. As the cement industry continues to develop more sophisticated blended cements, it will be even more clearly seen that a single parameter fails to capture the true complexity of a cement. In addition to measuring the Blaine, cement producers use the laser diffraction measurement of the entire particle-size distribution for quality control of their cements. Despite the wide use of this measurement by the cement industry, laser diffraction is not a standardized test. This project's goal was to examine various tests, such as laser diffraction and Blaine, that measure the particle-size distribution and total surface area of cement powder and then to determine the most appropriate test on the basis of correlation with the macroproperties of the cement paste or mortar. The shape of the cement particles for a partial particle size range was determined with X-ray computed microtomography (X-ray CT); the relationship between X-ray CT, the Brunauer-Emmett-Teller (BET) surface area method, laser diffraction, and Blaine measurements was explored. The more fundamental and sophisticated experiments, nitrogen BET and X-ray CT, were used as ground truth to critically evaluate the laser particle-size distribution and Blaine fineness measurements. The standardization of the laser diffraction test method is proposed.