Masonry Magazine September 2007 Page. 35
SAFER FASTER EASIER
The quantity of new reinforced masonry construction projects has increased steadily in the United States during the past several years, led primarily by commercial projects (big-box retail, hotels and low-rise residential) and school construction. Thus, ensuring that you are well informed on the latest requirements, specifications and materials for grouting masonry walls is a marketable skill that could mean more money in your pocket from new jobs. First, let's clarify what we're talking about.
Essentially, there are two forms of reinforced masonry construction (RMC): low-lift (simultaneous masonry construction and grouting), and high-lift (grouting after masonry construction). In either form, the majority of corefill grout is used with concrete masonry units, while only a small percentage is used with clay brick construction. With the low-lift method, grout is placed as the courses are laid. The grout then can be consolidated with a "pudding stick" or a mechanical vibrator. In the high-lift method, the masonry is built to the story height, or its full height (not exceeding 12.67 feet), after which grout is poured from a hopper or pumped by mechanical means. The grout then is consolidated with a low-force vibrator. When grouting between wythes, the vibrator should be placed in the grout at points spaced 12 to 16 inches apart.
The tasks seem simple enough, so why does there seem to be so much confusion on this issue?
Why All the Confusion?
FOR STARTERS, Jeff Leonard, vice president of bulk materials for The QUIKRETE Companies, said that because of the nature of masonry grout (with a 10-to 11-inch slump) some contractors think that vibration is not necessary. "This is not the case, however, especially if there is congested rebar within a wall," he said.
Further, according to some grout suppliers and other industry experts, the code changes within national and local regulations can lead to a great deal of uncertainty among mason contractors. (More changes are, in fact, planned for the national codes, including updates for self-consolidating grout.) Additionally, the introduction of self-consolidating grout (SCG) has led some contractors to believe that vibration was no longer necessary, as if all grouts provided SCG's self-consolidating qualities. It is important to note, however, that SCGs generally only reduce the need for vibration as opposed to eliminating it entirely.
"There is a lot of confusion about grout consolidation in the industry and ACI 530 tells us that anything over a 12-inch grout lift should be consolidated and reconsolidated. This however, does not always happen," said Nick Blohowiak, a regional manager for Minnesota-based SPEC MIX. "ACI also allows for this consolidation and reconsolidation to be modified, and even potentially eliminated, if an appropriate demonstration
GET THE TOOLS WHICH ARE THE NEW STANDARD
IN SAFETY AND COMFORT.
T BALTIMORE
HARD
For more information, or to purchase, call or go online
CAP BALTIMORE
TOOLWORKS
SAFETY TOOLS
made in USA
800-752-5533
WWW.HARDCAP.COM
CIRCLE 147 ON READER SERVICE CARD
A vinyl solution to an ironclad problem.
Vinyl Angle Iron Covers
The unpleasant sight of a rusty, corroded angle iron over your home's entryways and doors may now be easily avoided by using the new Vinyl Angle Iron Covers!
Available in 5 designer colors!
Visit us @ www.angleironcover.com
For information on becoming a distributor or to locate a dealer closest to you, call (800) 407-6266
CIRCLE 170 ON READER SERVICE CARD
September 2007
Masonry
33