Page 76 - Design of Reinforced Masonry Structures

MASONRY UNITS: APPLICATIONS, TYPES, SIZES, AND CLASSIFICATION 2.29

they can be placed conveniently around the reinforcing bars already in place. The major
advantage of this is the elimination of the need to lift the units over the tops of the rein-
forcing bar or to thread the reinforcement through the cores after the wall is constructed
(Fig. 2.21). Bond beam and lintel units are essentially U- or channel-shaped units that
are used to accommodate horizontal reinforcement. Bond beam units are characterized
by depressed webs to accommodate horizontal reinforcing bars. They are produced
either with reduced webs, or with “knock-out” webs which are removed prior to place-
ment in the wall. Lintel units are produced in various depths that may be required to
carry desired lintel loads over the door and window openings. The solid bottoms in
both bond beam and lintel units confine the grout. Pilaster and column units are used
to accommodate wall-column or wall-pilaster interface, and allow space for load-carrying
reinforcement.
Figure 2.22 shows examples of special
shape units, typically used in wall appli-
cations. Sash blocks are produced with
a vertical groove molded on one end to
accommodate a window sash. Sash blocks
can be laid adjacent to one another to
accommodate a preformed control joint
Sash unit All purpose or kerf unit
gasket. Control joint units have one male
and one female end to provide lateral load
transfer across the control joints. An all-
purpose or kerf unit is produced with two
closely spaced webs in the center instead
of typical one web. This permits the unit
to be split into two at the jobsite into two
8-in. blocks, which are typically used at
the ends or corner of a wall, or adjacent Control joint unit Bull-nosed unit
to an opening. Bull-nosed units are manu-
factured with single or double bullnose, to
soften corners. Screen units are produced
in a variety of shapes, sizes, and patterns.
Beveled-end units are produced with one
end oriented at 45°, which can be used
to form walls intersecting at 135°. It is
common to employ mechanical cutters at
jobsites where masonry units are used for Bevelled unit Screen units
construction, to cut modular units to the
desired size and shape, particularly for FIGURE 2.22 Special shape units. (Courtesy: PCA.)
joints where walls meet at angles other than
right angles (Fig. 2.23).
Figure 2.24 shows examples of special units designed to increase energy efficiency.
These units may have reduced webs to reduce heat loss through the webs. Reduction in
web areas can be accomplished by reducing web thickness or height, reducing the number
of webs, or both. In addition, the interior face shell of the unit can be made thicker than a
typical face shell for increased thermal storage.
Figure 2.25 shows examples of acoustical units designed for sound mitigation and
improving internal sound acoustics. These units are often used in churches, industrial
plants, and schools.
Figure 2.26 shows radial units that can be used for manholes, catch basins, valve vaults,
and underground structures. Figure 2.27 shows examples of architectural units. Customized
column and chimney units and chimney caps are shown in Fig. 2.28.