Using Nitrogen Adsorption to Quantitatively Study Microstructure of Cement Pastes
M. C. Garci and H. M. Jennings
Appears on pages(s):
absorption; cement past; nitrogen; water-cement ratio
Nitrogen adsorption is quick, inexpensive method for measuring the surface area of mesoporous materials. The use of this method for studying cement-based materials has generated much controversy in part because the values obtained are quite variable and differ from those measured using water adsorption, SAXS, SANS, or NMR techniques. No two measure the same surface area of cement paste. Although nitrogen may not measure all of the surfaces in a cement paste, a quantitative measurement of the surfaces accessible to nitrogen is till a valuable number. When variation due to sample preparations minimized, the effects of variables on the nitrogen B.E.T. surface area become clear. Evidence from the effects of w/c and age on surface area shows that there are two types of C-S-H can be manipulated, with potential effects on physical properties such as drying shrinkage and creep.