Page 340 - Masonry and Concrete

Masonry Garden Walls

339
MASONRY GARDEN WALLS

FIGURE 9-29
Grouted and reinforced CMU pilaster.

used, and truss-type joint reinforcement should be located in every
other bed joint for a maximum spacing of 16 in. on center. Because of
their decorative coring pattern, the way screen blocks are positioned
in the wall greatly affects their compressive strength. The National
Concrete Masonry Association (NCMA) tested a variety of screen block
designs to determine their relative strengths when turned different
ways. Figure 9-30 shows that the relative strength of the blocks tested
in the position shown can vary significantly as a percentage of the
same unit strength when tested with the core holes vertical. Units
should have a minimum compressive strength of 1,000 psi (gross area)
when tested with the holes in a vertical position parallel to the direc-
tion of the load.
Control joints in screen block walls should be located at one side of
each pilaster. To form the control joint, line one end of the pilaster
block with roofing felt or building paper before mortaring in the screen
block (Figure 9-31). Joint reinforcement should stop on either side of
the control joint and should not continue through it.

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