Porosimetric features of calcium sulfoaluminate and Portland cement pastes: testing protocols and data analysis

Investigating pore structure of calcium sulfoaluminate cement paste is significantly important to understand the hydration process of cement, to develop the models that describe the cement paste microstructure, and eventually to improve the properties of the cement paste such as shrinkage compensation and self-stressing. The history, manufacture, and hydration of calcium sulfoaluminate cement are investigated. Two most common experimental protocols, nitrogen sorption and mercury intrusion porosimetry, are systematically summarized with required theories for analysis of porosimetric features of the cement pastes. Both calcium sulfoaluminate and portland cement pastes were tested with a water-to-cement ratio of 0.4, 0.5, and 0.6 using the two test methods. Since the measurement range of pore diameter by the nitrogen sorption porosimetry is relatively narrow (about 0.3-300 nm), the microporous properties of cement paste can be well determined. The mercury intrusion porosimetry is useful to evaluate the porosimetric features of cement pastes including bulk durability due to the wide measurement range of pore diameter (approximately 3 nm-200 mu m).