Masonry Magazine July 2002 Page. 32
continued from page 29 and, because the inspector can be certain that all of the steel (rebar) is properly in place.
Whichever method is used, some "universals" are followed. Proper preparation of the grout space is very important. With high-lift, all mortar droppings and debris should be removed through the cleanout openings or by other approved methods. In high- or low-lift grouting, mortar that protrudes more than about 3/8 inch into the grout space should be removed so that grout will not bridge at these location causing incomplete filling of cores. When high-lift grouting is used, protrusions can be knocked off and removed through the cleanout openings; with low-lift, they should be removed as soon as the course is completed to make reaching them easier.
In high-lift, cleanouts and wall ties must be built into the wall and the collar joint must be at least 3 inches wide unless it contains no horizontal steel, in which case it may be 2 inches wide. The reason for such great width is to prevent the grout from hanging up and leaving voids in the wall.
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Vertical grout dams should be built into collar joints to control the horizontal grout flow. These dams should not be more than 25 inches apart. Without these dams the grout might segregate, or the inspector might find himself watching a continuous grout pour that takes all night to complete.
Cleanouts are usually created by omitting every other brick in the bottom course of one tier. Mortar droppings and other debris are flushed out daily. A good way to keep them from sticking to the foundation is to sprinkle some sand into the collar joint after each cleaning.
Quantity and quality
MIW SUGGESTS that after the wall has cured for at least three to five days, depending on the weather, and after the inspector has assured that the steel is properly placed and that the collar joint is clean, the cleanouts may be sealed and the wall grouted.
Normally, cleanouts are sealed by laid bricks braced to prevent them from blowing out. A better way, which can be used when the bottom course is not exposed to view, is merely to brace a plank against the bottom course. The contractor saves the expense of laying all those closer bricks and, when the plank is removed, the inspector has a foolproof way to inspect the bottom of the grout pour.
Using the low-lift technique, grouting should proceed in lifts not more than 4 feet before puddling or consolidating. Grouting of any section between dams should be completed in one day with no interruptions over an hour long. Grouting too rapidly might blow out the wall; too long an interruption might cause shrinkage cracks or laitance.
Dentinger, who works in the cold winters of Minnesota, notes that weather can make a difference in the choice of high- or low-lift. "In the winter, the cover of the