b) The masonry units are cold. However, if
protection requirements included in the
units are below 5C (41F), they must be
Council's guide specifications. The proposal
allowed to warm up in a heated shelter.
was submitted through NCMA, which is a
member of that council.
2. Increased thermal protection is required for
masonry constructed using wet masonry
A new standard test method was developed
units. Therefore, it is recommended that
and adopted by ASTM under specification C
masonry units delivered to the job site be pro-
1262, "Standard Test Method for Evaluating
tected from moisture as much as possible.
the FreezeThaw Durability of Manufactured
Units that are visibly damp should not be
Concrete Masonry Units and Related Con-
laid. It is generally not considered necessary
crete Units." This new standard has been
to dry wet units by heat. Air drying is typically
published in the ASTM Annual Book of Stan-
sufficient, provided units are unstacked and
dards.
separated to permit air flow between them.
This study showed that antifreeze admixtures
3. The practice of heating the mortar ingredi-
can promote appreciable strength in mortar when
its internal temperature is below 0C (32F). How-
ents prior to mixing to temperatures greater
than 5C does not provide significant thermal
ever, these products are yet to become commer-
protection. In addition, very high water tem-
cially available.
peratures may cause flash set. Therefore, it is
recommended that the mortar mix be pro-
LITERATURE CITED
duced at temperatures of 5 to 20C (41 to 68F).
Korhonen, C.J., E.R. Cortez, and R.D. Thomas
4. Antifreeze admixtures originally developed
(1996) Minimum thermal protection requirements
for concrete provide enhanced performance
for cold weather masonry. In Proceedings of the 8th
to masonry mortar. The experiments con-
International Cold Regions Engineering Specialty
ducted in this project support a recommenda-
Conference. American Society of Civil Engineers,
tion for their use in masonry mortars as soon
New York.
as they become commercially available.
IMIAWC (1988) Recommended Practices and Guide
Specifications for Masonry Construction. Internation-
COMMERCIALIZATION AND
al Masonry Industry All Weather Council. Wash-
TECHNOLOGY TRANSFER
ington, D.C.: International Masonry Institute.
Korhonen, C.J., E.R. Cortez, B.A. Charest, and C.E.
The knowledge derived from this research is
Smith, Jr. (1994) Low-temperature admixtures for
being shared with the engineering community
concrete. In Proceedings of the 7th International Cold
through conference papers, technical reports, up-
Regions Engineering Specialty Conference. American
dates to guide specifications, and new testing
Society of Civil Engineers, New York.
methods:
Sneck, T. (1972) The interaction between mortar
A conference paper was presented at the
and masonry units as a basis for standards for ma-
American Society of Civil Engineers 8th In-
ternational Specialty Conference on Cold Re-
sium Proceedings, NBS Special Publication 361, vol.
gions Engineering in Fairbanks, Alaska, in
1. Washington, D.C.: U.S. Department of Com-
August of 1996. The paper was published in
merce, National Bureau of Standards.
the proceedings of this conference.
Washburn, E.W. (1921) Note on a method of deter-
mining the distribution of pore sizes in a porous
A proposal (Appendix F) was submitted to
material. In Proceedings of the National Academy of
the International Masonry Industry All Wea-
Sciences, U.S., vol. 7, p. 115116.
ther Council to update the minimum thermal
28
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