Masonry Magazine January 2007 Page. 48
Mortar Admixtures
The drawback to laborers adding the admixtures themselves is that they can miscalculate how much is needed, which results in an inconsistent amount per batch.
Admixtures continued from p.38
cold weather, below freezing, with a pre-blend, you still have to use warm water, and you have to keep the wall protected from freezing.
When mixing a pre-blended mortar that has an accelerator in temperatures below 40 degrees Fahrenheit, mason contractor crews need to heat the water to between 40 and 120 degrees, just like they would if they were adding the admixture themselves, he said.
"None of these admixtures creates short cuts," Leonard said. There are, however, admixtures that are easily added in the field. The key to mixing them into the mortar on the job site is to add them right after putting in the water, before the sand and cement are added. This allows the admixture to mix evenly in the batch.
"You want the admixture dispensed evenly throughout the water," Leonard said. The drawback to laborers adding the admixtures themselves is that they can miscalculate how much is needed, which results in an inconsistent amount per batch, he said. This can change the tooling characteristics or make the mortar color slightly lighter or darker.
"If it's not consistent, it can show up on the finished, tooled wall," Leonard said. "More importantly, if you tool the joints too early, the color may be lighter. If you tool later, the color may be darker."
Admixtures at Work
SIMPLY: Each admixture has a specific job to do. While accelerators and retarders are the most common, there are others that play vital roles in masonry construction. For instance, water repellant admixtures are used to block or impede water penetration. This mortar admixture works
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