The Blaine fineness (Blaine) of a cement powder is a single parameter that is meant to characterize the specific surface area of a cement, and is assumed to be linked to physical and mechanical properties such as strength, setting time, and rheology. A single parameter cannot characterize the particle size distribution of a cement. And as the cement industry continues to develop more sophisticated blended cements, a single parameter will increasingly fail to capture a cements true complexity. The laser diffraction (LD) measurement of the entire particle size distribution is currently being used by cement producers for quality control of their cements while still measuring the Blaine, which is based only on an empirical surface area measurement. Despite its wide use by the cement industry, LD is not a standardized test. This projects goal is to examine various tests, such as laser diffraction and Blaine, which measure the particle size distribution (LD only) and total surface area of cement powder (both tests), and then determine the most appropriate test based on correlation with macro-properties of the cement paste or mortar. In addition, the shape of the cement particles, for a partial particle size range, was determined using X-ray computed micro-tomography (CT) and the relationship between X-ray CT, Brunauer-Emmett-Teller surface area method (BET) (surface area), laser diffraction, and Blaine measurements was explored. The more fundamental and sophisticated experiments, nitrogen BET for surface area and X-ray CT for particle shape, 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.
Citation: AASHTO report
Pub Type: Others
cement fineness, BET, laser diffraction, Shape, CT-Scan