Frequently Asked Questions (FAQs)
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Frequently Asked Questions
Q: What kind of ties should
be used with concrete masonry walls?
Q:
How should mortar strength be chosen? Isn’t the strongest
mortar best for every project?
Q: What is the preferred
method of coloring mortar?
Q: How can new masonry
under construction be heated to protect it from the cold?
Q: Is efflorescence
more common in the winter and if so, why?
Q: How cold
can it get before masonry under construction requires protection?
 |
| Masonry building under construction enclosed
with tarps. |
A: There are different levels of protection
required for different temperature ranges, but the first demarcation
is at 40F (4.4C). Other critical temperatures for masonry being
constructed are 32F (0C), 25F (-3.9C), and 20F (-6.7C). As temperatures
drop, protective measures become more stringent.
Requirements and critical temperature ranges are slightly different
for work in progress compared to newly completed masonry. The MSJC
Specification establishes the requirements for both.
For additional information, see Cold
Weather Masonry Construction (IS248) and Masonry
Today Newsletter,
Vol. 12, No. 2, Winter 2002/2003 (PL382), which is available
as a free download.
Q: How can new masonry
under construction be heated to protect it from the cold?
 |
| Heating water in drums |
A: Protective measures for masonry that
is being constructed include heating materials, covering or enclosing
the construction area, adding heat to the enclosures, and combinations
of the techniques.
During construction, it is usually easiest to heat the ingredients.
Water can easily be heated in drums and has a large thermal capacity.
Given the right equipment, sand can be heated without much difficulty.
Heating cement is not an effective approach for raising the temperature
of fresh mortar or grout for masonry construction.
For additional information, see Cold
Weather Masonry Construction (IS248) and Masonry
Today Newsletter,
Vol. 12, No. 2, Winter 2002/2003 (PL382), which is available
as a free download.
Q: We notice an
increased occurrence of efflorescence now that the weather is colder.
Is efflorescence more common in the winter and if so, why?
 |
| Efflorescence deposits on newly constructed
masonry wall |
A: Efflorescence is a crystalline deposit,
usually white, that may develop on the surfaces of masonry construction.
Efflorescence comes from dissolved materials from within masonry,
is usually harmless, and is actually more common in cooler weather
than in warmer weather, all else being equal. Moisture travels through
masonry more slowly at lower temperatures and is slower to evaporate
from the face of the wall. The slower rate allows the moisture to
dissolve a greater amount of soluble compounds and increases the risk
of them remaining on the surface.
For additional information and remedies, see Trowel
Tips: Efflorescence
(IS239)
|