2.6
WATER
Suitable for domestic consumption, and free of mineral and organic
substances that affect the hardening and durability of the plaster or
stucco.
2.7
PROPORTIONING
Unless specified otherwise, materials are specified on a volume basis and
shall be measured in approved containers, to ensure that the specified
proportions will be controlled and accurately maintained during the
progress of the work. Measuring materials with shovels (shovel count) will
not be permitted. Prepare ready-mix gypsum plaster for use by the addition
of water only.
2.7.1
Gypsum Base Coat Plaster
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NOTE: List all conditions where sand or lightweight
aggregate should not be used.
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Sand or lightweight aggregate is optional in gypsum plaster basecoats
except provide (1) sand for Keene's cement and high strength gypsum-gaged
finish coats; (2) lightweight aggregate when necessary for a required fire
resistance rating [; and (3) [_____]].
2.7.1.1
Sand and Gypsum Plaster Base Coat
Mix scratch coat in the proportion of 45 kg 100 lb of gypsum neat plaster
to not more than 56 l 2 cu ft of damp loose sand; mix brown coat in the
proportion of 45 kg 100 lb of gypsum neat plaster to not more than 85 l 3
cu ft of damp loose sand; or scratch and brown coats may both be mixed in
the proportion of 45 kg 100 lb of gypsum neat plaster to not more than 70 l
2 1/2 cubic feet of damp loose sand. [Mix the basecoats for double-up work
in the proportion of 45 kg 100 lb of gypsum neat plaster to [not more than
70 l 2 1/2 cu ft of damp loose sand on gypsum lath] [and] [not more than 85
l 3 cu ft of damp loose sand on masonry].]
2.7.1.2
Lightweight Aggregate and Gypsum Plaster Base Coat
Mix scratch coat in the proportion of 45 kg 100 lb of gypsum neat plaster
to [not more than 70 l 2 1/2 cu ft of lightweight aggregate on gypsum
lath,] [and] [not more than 85 l 3 cu ft of lightweight aggregate on
masonry]. Mix brown coat in the proportion of 45 kg 100 lb of gypsum neat
plaster to [not more than 70 l 2 1/2 cu ft of lightweight aggregate on
gypsum lath] [and] [not more than85 l 3 cu ft of light weight aggregate on
masonry]. Where plaster thickness exceeds 25 mm one in, the aggregate
proportion may be increased to 85 l 3 cu ft. [Mix the basecoats in
two-coat double-up work in the proportion of 45 kg 100 lb of gypsum neat
plaster to [not more than 70 l 2 1/2 cu ft of lightweight aggregate on
gypsum lath] [and] [not more than 85 l 3 cu ft of lightweight aggregate on
masonry]]. Gypsum ready-mixed plaster with perlite aggregate may be
provided in lieu of field-mixed lightweight aggregate and gypsum plaster,
provided the specified proportion of aggregate to plaster does not exceed
the proportion specified for field-mixed plaster.
SECTION 09210
Page 9
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