Page 149 - Masonry and Concrete

Masonry Construction Techniques
148 CHAPTER FIVE

QUICK>>>TIP (IRA) or high suction. High-suction bricks
To test a brick for should be wetted with a garden hose a day
excessive absorption, draw a circle the or so before they will be used so that mois-
size of a quarter on the bed surface using ture is fully absorbed into the units but the
a crayon or wax pencil. With a medicine
surfaces are dry to the touch before being
dropper, place twelve drops of water
laid. Some experts recommend that brick
inside the circle and time how long it
not be wetted in winter because some
takes to be absorbed (Figure 5-11). If
high-suction units produce better bond
the water is completely absorbed in less
strength in cold weather than low-suction
than one minute, the brick is too dry.
units. Even though it is very absorptive,
concrete block should never be wetted
before placement because this will
increase unit shrinkage and the possibility
CRAYON OR
EYE WAX PENCIL of cracking in the finished wall. For this
DROPPER CIRCLE THE reason, it is particularly important to keep
SIZE OF A concrete block covered and protected at
QUARTER
the job site. All masonry units should be
clean and free of contaminants such as
dirt, oil, or sand that might interfere with
mortar bond.

5.2.5 Reinforcement, Connectors,
and Accessories
Reinforcement and accessories should be
FIGURE 5-11
checked for correct size and configuration
Field test of brick absorption. and for adequate quantities to complete
the work. Before placing reinforcing steel
or metal accessories in the wall, oil, dirt, ice, and other contaminants
should be removed so that a good bond can be achieved with the mor-
tar or grout.

5.3 Mixing Mortar

Mortar is the cementitious material that bonds units, connectors, and
reinforcement together for strength and weather resistance. Although
it contributes to the compressive strength of the masonry, mortar’s pri-
mary functions are in providing bond strength and in sealing the joints
between units against the passage of air and water. To perform these

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