coated with bituminous compound or other waterproofing agents, or (2) that
have been painted or previously plastered. Before plaster work is started,
wet masonry and concrete surfaces thoroughly with a fine fog spray of clean
water to produce a uniformly moist condition. Lath and accessories are
specified in Section 09205N FURRING AND LATHING. Check metal grounds,
corner beads, screeds, and other accessories carefully for alignment before
starting work. [Do not apply gypsum plaster to surfaces containing frost.]
3.2
WORKMANSHIP
3.2.1
Slump Tests
Apply Plaster by hand or machine. When a plastering machine is used,
control the fluidity of gypsum plaster to have a slump of not more than 75
mm 3 in when tested using a 50 by 100 by 150 mm 2 by 4 by 6 in high slump
cone, Subsequent to determining water content to meet the specified slump,
do not add additional water to the mix. Conduct the slump test according to
the following procedure:
a.
Place cone on level, dry, non-absorptive base plate.
b.
While holding cone firmly against base plate, fill cone with
plaster taken directly from the hose or nozzle of the plastering
machine, tamping with metal rod during filling to release air
bubbles.
c.
Screed off plaster level with top of cone. Remove cone by lifting
it straight up with a slow and smooth motion.
d.
Place cone in a vertical position adjacent to freed plaster
sample, using care not to shake or move base plate.
e.
Lay a straightedge across top of cone, being careful not to shake
or move cone. Measure slump in mm in from the bottom edge of the
straightedge to the top of the slumped plaster sample.
3.2.2
Application
Apply gypsum plaster in three coats, except as follows:
a.
Gypsum plaster applied to [masonry] [and] [gypsum lath] using the
two-coat double-up method.
Apply base coats with sufficient pressure and ensure plaster is
sufficiently plastic to provide a strong bond to bases. Work base coats
into screeds at intervals from 1500 to 2400 mm 5 to 8 ft. Plaster shall
not be continuous across expansion and control joints occurring in walls,
partitions, and ceilings. Finish work level, plumb, square, and true,
within a tolerance of 3 mm in 2400 mm 1/8 in in 8 ft, without waves,
cracks, blisters, pits, crazing, discoloration, projections, or other
imperfections. Form plaster work carefully around angles and contours, and
well-up to screeds. Take special care to prevent sagging and consequent
dropping of applications. There shall be no visible junction marks in
finish coat where one day's work adjoins another. [Plastered surfaces to
receive [rubber or vinyl base coves] [wood base boards] shall extend to
wood ground indicated as backing for base.] Plaster not required behind
built-in cabinets and equipment [, and [_____]].
SECTION 09210
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