Masonry Magazine January 2007 Page. 50
Mortar Admixtures
"When cleaned to reveal the original intended appearance, it's hard to come up with a better looking exterior for a building than masonry." Gary Henry, business communications specialist for PROSOCO.
QUIKRETE's Leonard warned that the reduced water-to-cement ratio of these admixtures is not necessarily a good idea since they can make the mortar too strong.
"An owner or architect may be sold on the idea that stronger is better, particularly concerning mortar and masonry unit strength. However, you always want the mortar to be weaker than the masonry units themselves," Leonard said. "While you never want a wall to crack, if unavoidable, it is best to have the mortar absorb the stress and crack as opposed to the brick, stone or block. Mortar is far less costly a repair than replacing or repairing cracks in the masonry unit."
Keep It Clean
Ideally, admixtures don't impact cleaning the finished wall, but masons need to make sure the admixtures won't react to the chemicals in the cleaner before they apply it to the wall.
Masons need to make sure the admixtures won't react to the chemicals in their cleaners.
"When cleaned to reveal the original intended appearance, it's hard to come up with a better looking exterior for a building than masonry," said Gary Henry, business communications specialist for PROSOCO, in Lawrence, Kan., which makes cleaning products for masonry walls. "If the cleaner is not used correctly, the opposite is true. You can ruin the job beyond repair. Careers have been ruined and fortunes lost because of this."
The possible combinations of masonry, mortar-type, admixtures and cleaners are practically unlimited, Henry said. Therefore, the best practices are to only use cleaners from a reputable company that backs up its products, and to test the cleaner on a small, out of the way area before cleaning the entire wall. Changes in the dilution rate or dwell time may solve any problems. If not, mason contractors should consult the cleaner manufacturer.
"There are many kinds of admixtures for many different purposes. Some may react with certain types of cleaners to cause stains. Other admixtures may make excess mortar more difficult to remove. Still other admixtures may make the mortar easier to remove," Henry said. "Complicating the matter is the type of masonry used. A concrete masonry, for instance, with an admixture that makes the mortar more difficult to remove could be problematic, since concrete masonries may be etched by more powerful cleaners, stronger dilutions or longer dwell times."
Jablonski suggested admixture manufacturers should play a role by explicitly stating recommended cleaning guidelines to eliminate potential problems. "For us, it's a good rule of thumb to specify the cleaning procedure," he said.
As long as mason contractors and their crews use the right tool in this case, the right cleaner for the job, they won't have any problems, Henry said.
"We make products that address the qualities of each specific substrate," he said, noting that brick, block and stone each have their own qualities, so they need their own cleaners. "If you're smart, you'll use the most specific tool you can. The real, true professional people understand that you need the right product for the right job." Brett Martin is a freelance writer located in Shakopee, Minn
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