Page 77 - Design of Reinforced Masonry Structures

2.30 CHAPTER TWO

FIGURE 2.23 A mechanical cutter in use at a jobsite. (Courtesy: Author.)

FIGURE 2.24 Examples of concrete masonry units FIGURE 2.25 Examples of acoustical concrete
designed for energy efficiency. (Courtesy: PCA.) masonry units. (Courtesy: PCA.)

2.6.8 Sizes of Concrete Masonry Units
Concrete masonry units, produced in a variety of sizes are specified by their sizes: width
(thickness), height, and length, in that order. It is common practice to specify units by their
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nominal sizes, although the actual sizes are shorter by ⁄ 8 in., to allow for the thickness
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( ⁄ 8 in.) of typical mortar joint. For example, an 8 × 8 × 16 standard concrete masonry unit
has its nominal dimensions as 8 in. wide (7 ⁄ 8 in. actual), 8 in. high (8 ⁄ 8 in. actual) and 16 in.
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5
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long (15 ⁄ 8 in. actual). Figure 2.29 presents the nomenclature for various parts of a hollow
CMU. In the finished wall, the joint-to-joint distance will be equal to one of the nominal
block dimension. A hollow CMU may have two or three cells, referred to as two- or three-
core units, respectively; a half unit has only one cell. The cells are used for the placement