Mercury intrusion porosimetry

results in graphical form. Appendix D presents

Mercury intrusion porosimetry (MIP) is a new-

individual results from each sample tested.

er technique that determines the pore size distri-

bution in porous materials such as rock, concrete,

Microscopic examination of the air void system

and mortar. Its use with masonry is still a subject

A test method used to assess the susceptibility

of research. Samples from the specimens that

of porous materials to freezing and thawing is

were freezethaw-tested as described above were

ASTM C 457, "Standard Practice for Microscopical

also tested by mercury intrusion porosimetry.

Determination of Air-Void Content and Para-

Small samples were enclosed in a small test

meters of the Air-Void System in Hardened Con-

chamber capable of withstanding high pressures.

crete." Although this test method was developed

Mercury was injected into the chamber to fill the

for concrete, its principles may be used for other

air space available. Higher pressures are needed

concrete-like materials. The specimens are saw-cut

to intrude mercury into smaller pores. The pres-

slabs that are ground and polished and then

sure was increased gradually and the amount of

observed through a stereo microscope. The main

mercury that went into the chamber was record-

parameters of the test are the air content and the

ed. The pressure needed to intrude mercury was

spacing factor, an indication of the distance within