are tooled, remove mortar from exposed surfaces with fiber brushes and
wooden paddles. Protect base of walls from splash stains by covering
adjacent ground with sand, sawdust, or polyethylene.
3.1.4
Loads
Do not apply uniform loads for at least 12 hours or concentrated loads for
at least 72 hours after masonry is constructed. Provide temporary bracing
as required.
3.1.5
Surfaces
Surfaces on which masonry is to be placed shall be cleaned of laitance,
dust, dirt, oil, organic matter, or other foreign materials and shall be
slightly roughened to provide a surface texture with a depth of at least 3
mm 1/8 inch. Sandblasting shall be used, if necessary, to remove laitance
from pores and to expose the aggregate.
3.2
LAYING MASONRY UNITS
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NOTE: Specify bond pattern for each type of
masonry. Where more than one bond pattern is
required, the drawings should indicate the location
and extent of each bond pattern. Bond patterns for
reinforced hollow masonry construction should be
such that cores of units will be in alignment
vertically. Where stacked bond is specified in
reinforced hollow masonry, horizontal rebars shall
be provided at 600 mm (2 foot) intervals or
horizontal joint reinforcement must be required in
every other horizontal joint to provide mechanical
bond between adjacent units. Veneers should be
anchored at 300 mm (12 inches) on centers vertically
when stacked bond is used and 400 mm (16 inches) on
centers vertically when running bond is used. The
use of stacked bond is discouraged and should only
be permitted for small wall areas to give an
architectural feature, such as for a building
entrance detail.
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Coordinate masonry work with the work of other trades to accommodate
built-in items and to avoid cutting and patching. Masonry units shall be
laid in [running] [stacked] [the indicated] bond pattern. Facing courses
shall be level with back-up courses, unless the use of adjustable ties has
been approved in which case the tolerances shall be plus or minus 13 mm 1/2
inch. Each unit shall be adjusted to its final position while mortar is
still soft and plastic. Units that have been disturbed after the mortar
has stiffened shall be removed, cleaned, and relaid with fresh mortar. Air
spaces, cavities, chases, expansion joints, and spaces to be grouted shall
be kept free from mortar and other debris. Units used in exposed masonry
surfaces shall be selected from those having the least amount of chipped
edges or other imperfections detracting from the appearance of the finished
work. Vertical joints shall be kept plumb. Units being laid and surfaces
to receive units shall be free of water film and frost. Solid units shall
be laid in a nonfurrowed full bed of mortar. Mortar for veneer wythes
shall be beveled and sloped toward the center of the wythe from the cavity
side. Units shall be shoved into place so that the vertical joints are
SECTION 04200
Page 39
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