Page 174 - Masonry and Concrete

Masonry Construction Techniques
173
MASONRY CONSTRUCTION TECHNIQUES

on the side walls of the cores and the rein-
forcing bars, leaving voids in which the
steel is not properly bonded or embedded
and is much more susceptible to corrosion
from moisture within the wall.

5.7 Protections

During construction, partially completed
masonry work requires some protection
from damage caused by weather or by
other construction operations.
TEMPORARY
5.7.1 Bracing BRACING

High-lift grouting requires that walls be
temporarily braced until the mortar and
grout has fully set. Partially completed
walls should also be braced during con-
struction against lateral loads from wind FIGURE 5-32
or other forces applied before full design Bracing provides wind load resistance during con-
strength is attained or before permanent struction. (from NCMA, TEK 72, National Concrete
Masonry Association, Herndon, VA).
supporting construction is completed (Fig-
ure 5-32). Partially completed structures
may be subject to loads which exceed their structural capabilities.
Wind pressure, for instance, can create four times as much bending
stress in a new, freestanding wall as in the wall of a completed build-
ing. Fresh masonry with uncured mortar has no tensile strength to
resist such lateral forces. Most codes require that new, uncured, unan-
chored walls be braced against wind pressure. Bracing should be pro-
vided until the mortar has cured and the wall has been integrally tied
to the structural frame of the building. Bracing should be designed on
the basis of wall height and expected wind pressures.

5.7.2 Coverings
Masonry walls should be covered at the end of each day and when
work is not in progress. Excess moisture entering the wall during con-
struction can cause saturation of units, which may take weeks or
months to dry out. Such prolonged wetting may result in efflorescence,

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