Title:
Determination of Surface Area of Portland Cement and Silica Fume by Mercury Intrusion Porosimetry
Author(s):
Jan Olek, MenashiI D. Cohen, and Colin Lobo
Publication:
Materials Journal
Volume:
87
Issue:
5
Appears on pages(s):
473-478
Keywords:
BET method, compacting; mercury; porosimeters; porosity; portland cements; silica fume; specific surface determination; Materials Research
DOI:
10.14359/1864
Date:
9/1/1990
Abstract:
A new method for determining the surface area of portland cement and other cementing materials using a high-pressure mercury intrusion porosimeter (MIP) is introduced. For illustration, the surface area of three powder samples--portland cement, bulk (as-received) silica fume, and densified silica fume--were measured. The method accounts for initial compaction of the bed of powder prior to intrusion of mercury in interparticle (void) spaces. Surface area values obtained by the MIP method are in good agreement with those obtained using the gas adsorption method (BET N2), differing by only + 2.8 percent for portland cement, - 0.4 percent for bulk silica fume, and + 9.4 percent for densified silica fume. These differences could perhaps be attributed to differences in the nature of the tests and inherent limitations associated with each of them. The MIP method is simple and straightforward. Coupled with the relative ease of operating a modern porosimeter, it could perhaps gain some popularity in the concrete industry, particularly among silica fume users and producers. The method not only allows for the determination of surface area by itself, it also yields the values of total porosity, size distribution of pores, and compactibility of powder. The method should be tested for other cementing materials, such as fly ash and slag.