US EPA

4959949 

Journal Article 

Mercury porosimetry - An inappropriate method for the measurement of pore size distributions in cement-based materials 

Diamond, S 

2000 

Yes 

Cement and Concrete Research
ISSN: 0008-8846 

30 

10 

1517-1525 

10.1016/S0008-8846(00)00370-7 

WOS:000165977700001 

The conditions that must be met for mercury intrusion porosimetry (MIP) measurements to provide valid estimates of the pore size distribution of porous solids are reviewed. Evidence is presented indicating that these conditions are not satisfied in cement-based systems. In cement-based systems, nearly all of the mercury intrusion is held up until pressure corresponding to the threshold diameter is reached; subsequently, large and small pores are filled indiscriminately. Air voids, in sizes up to several hundred micrometers, are present in most pastes in substantial volume, unless the pastes were mixed under vacuum; these air voids are also not intruded until the threshold pressure is reached, and are recorded as fine (ca. 0.1 mum) pores. It is concluded that MIP measurements are useful only to provide threshold diameters and intrudable pore space measurements, which can serve as comparative indices for the connectivity and capacity of the pore systems in hydrated cements. MIP measurements should be abandoned as measures of the actual pore sizes present. (C) 2000 Elsevier Science Ltd. All rights reserved. 

mercury porosimetry; pore size distribution; image analysis; backscattered electron imaging; microstructure