Page 359 - Masonry and Concrete

Retaining Walls
358 CHAPTER TEN

walls. Masonry can be grouted course by
course as the wall is laid, or several courses
STOP GROUT can be laid and the grout poured after the
3/4" BELOW wall has cured for a day or two. Grout for
TOP OF
MASONRY pours up to 4 ft. in height should be mixed
TO FORM to a fluid consistency that will flow easily
“KEY” WITH
NEXT POUR into the wall cavity or block cores and sur-
round the reinforcing bars. Grout should be
rodded or vibrated to remove voids. Rein-
forcing bar positioners are used to hold the
vertical steel in place until it is grouted.
3
Stop the grout about 4 in. below the top of
the masonry retaining so that it will form a
“key” with the next pour (Figure 10-13). A
flashing course is installed under the cop-
ing in masonry retaining walls to protect
the top of the wall from moisture.
Backfilling should not begin for at least
FIGURE 10-13 three weeks after a concrete or masonry

Grout key. wall has been completed. The gravel and
soil backfill should be placed in depths of
12 to 24 in. at a time to avoid large impact
loads. Earth-moving equipment should be kept away from the wall a
distance equal to the wall height to avoid surcharge loading.

10.3 Segmental CMU Retaining Walls

Mortarless interlocking concrete masonry unit systems make the con-
struction of retaining walls simple and easy to accomplish even with
unskilled labor. Sold under a number of different trade names, these
systems are available through concrete block manufacturers, masonry
distributors, lumber yards, and home centers throughout the country.
The units are usually made in a rough, stone-like textures and in colors
ranging from grey to buff or earth tones. These systems are called seg-
mental retaining walls (SRWs), and there are two basic types. Conven-
tional SRWs are structures that resist the force of the retained soil
solely through gravity and the inclination or batter of the SRW units
toward the soil embankment (Figure 10-14). Conventional SRWs may

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