Masonry Magazine October 2008 Page. 40
MORTARS
can Society for Testing and Materials in West Conshohocken, Pa.) committee for manufactured stone is finalizing their installation instructions and, generally, it's a type S masonry cement that they're recommending. The mortars that are available have proven to be applicable."
Mortar cement is becoming more visible. It is produced as a way to satisfy the requirements that came out of the uniform building code. Those requirements were also written into the international building code. Mortar cement is a product that has the strength that you typically get from cement lime mortar, but it has the majority of hydrated lime removed, so it is more user friendly for the mason.
"That having been said," Kjorlien says, "while more and more specifications are calling for mortar cement, it is presently only available in grey, and it's required to be used in a higher seismic design category, D or greater. It's generally used for structural purpose only in reinforced CMU construction, not so much for veneers.
"We're seeing mortar cement become more prevalent in some parts of the country, so it might be something for masonry contractors to become acquainted with," he adds. "In my personal education work with LaFarge, I'm doing a program on what mortar cement is, why it exists, how it is the same and how it is different from what we have now. If there's anything new in mortar, the movement in the direction of mortar cement would be it."
Significant from the building code arena, the international building code now recognizes masonry cement in some applications that previously only permitted mortar cement or cement lime mortar. That could be good news for mason contractors. Most contractors and masons would prefer to work with masonry cement, because it doesn't have the deleterious affects of lime, so it saves the hands and has better board life, requiring less tempering,
"We've seen the requests for mortar for stone veneers and manufactured stone," says King, "but also for heavy natural stone that needs a little bit of a different formulation. We have come out with a new water resistant mortar to be used with the water-resistant masonry units that are now becoming much more popular."
Spec Mix's Blohowiack discusses some of the new mortars for new masonry products: "Over the years, we've developed a standard stone veneer mortar and a polymer-modified stone veneer mortar, or a bond-enhanced stone veneer mortar. We've taken the materials and pre-designed them in our facilities with the help of laboratories to hit very specific specs or performance criteria. For example, for stone veneer mortar or a bond-enhanced or polymer-modified version of it, we're meeting ANSI standards, ANSI 118.4. It drastically outperforms the standard masonry mortar in terms of bond strength."
Stone has been used for thousands of years in masonry. Many different types of stone exist, and masonry mortars are being developed based on the densities of those various stones. "If I've got a porous stone, I don't use a very low water-retention mortar that would be stronger than the stone, causing it to fail," says Blobowiack. "The opposite would be true of a very dense stone. Brick masonry units that may or may not be sealed or have a texture to them-for instance, split-face masonry unit-require the same approach. And, it's not just a couple of mortars, we're talking about different types of stone veneer mortars, straight-stone mortars, accelerated mortars for use at lower temperatures, set-delayed mortars, etc. All of these things are being developed and used in the masonry industry."
Traditional masonry and masonry mortared structures will continue to be solid architectural trends. But, as in all fields, there are constant changes to be aware of. And, as the man said, "...mortar is not the least important component of the wall, it's probably the most important." So keep training your masons, learn to recognize and handle the new blends, know when and where to employ them, and "keep current." IMAS Tom Inglesby is a San Diego-based writer and winner of the Construction Writers Association's 2002 Boger Award for Special Reports.
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