coat [L] [C].
3.13.2
Lime-Putty Finish
Lime-putty finish shall be mixed in the proportion of 1 part of gypsum
gauging plaster, calcined gypsum, to 3 parts of lime putty by volume. The
mix shall be approximately equivalent to one 45 kg 100 pound bag of gypsum
plaster to four 23 kg 50 pound bags of hydrated lime or 0.13 cubic meters
4.5 cubic feet of lime putty or 0.13 cubic meters 35 gallons of lime putty.
Perlite or vermiculite aggregated base coats shall have 23 kg 50 pounds of
fine white sand or 0.014 cubic meters 1/2 cubic foot of perlite fines added
for each 45 kg 100 pounds of gauging plaster.
3.13.3
Prepared-Gypsum Finish
Prepared-gypsum finish shall be mixed with water to the proper consistency
in accordance with manufacturer's published instructions. Prepared-gypsum
finish shall have a minimum compressive strength of not less than 2 MPa 300
psi when tested in accordance with ASTM C 472. Prepared gypsum finish
shall be used only over sanded base coats.
3.13.4
Keene's Cement Finish
Keene's cement finish shall be mixed in the proportions of 45 kg 100 pounds
of Keene's cement to 11 kg 25 pounds, dry weight, of hydrated lime. The
mix shall be approximately equivalent to one 45 kg 100 pound bag of Keene's
cement to one-half 23 kg 50 pound bag of hydrated lime or 23 kg 50 pounds
lime putty or 0.017 cubic meters 4-1/2 gallons lime putty. Subject to
approval, 5 kg 10 pounds of fine white sand may be added to the above mix.
When mixing mechanically, the water shall be put into the mixer first, then
the lime, the white sand if used, and finally the Keene's cement.
3.13.5
High-Strength Gypsum Finish
High-strength gypsum finish shall be mixed by dry weights in proportions of
45 kg 100 pounds of high-strength gypsum gauging plaster to 45 kg 100 pounds
of hydrated lime or 90 kg 200 pounds of lime putty. Gypsum gauging
plaster for high-strength finish coat shall be mixed with lime putty in
accordance with ASTM C 28/C 28M. Gauging plaster shall have a compressive
strength not less than 21 MPa 3000 psi when tested in accordance with ASTM
C 472. Factory-mixed gypsum finishing plasters shall equal or exceed the
performance requirements of job-mixed finishing plasters.
3.13.6
Portland Cement-Plaster Finish
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NOTE: Select finish coat from table 3 of ASTM C
926. Use finish coat FL for general use, and finish
coat F for abrasion resistance.
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The finish coat shall be proportioned and mixed in accordance with ASTM C
926, coat [FL] [F].
3.14
MACHINE APPLICATION
A plastering machine may be used for the application of scratch and brown
coats. Plaster for machine application shall be a special plaster
compounded and packaged by the manufacturer for this purpose. Slump cone
SECTION 09200A
Page 21
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