3.6
PREPARATION OF CONCRETE AND CEMENTITIOUS SURFACE
3.6.1
Concrete and Masonry
a.
Curing: Concrete, stucco and masonry surfaces shall be allowed to
cure at least 30 days before painting, except concrete slab on
grade, which shall be allowed to cure 90 days before painting.
b.
Surface Cleaning:
Remove the following deleterious substances.
(1) Dirt, [Chalking,] Grease, and Oil: Wash new [and existing
uncoated] surfaces with a solution composed of 0.2 liter 1/2 cup
trisodium phosphate, 0.1 liter 1/4 cuphousehold detergent, and
6.4 liters 4 quarts of warm water. Then rinse thoroughly with
fresh water. [Wash existing coated surfaces with a suitable
detergent and rinse thoroughly.] For large areas, water blasting
may be used.
(2) Fungus and Mold: Wash [new] [, existing coated,] [and
existing uncoated] surfaces with a solution composed of 0.2 liter
1/2 cup trisodium phosphate, 0.1 liter 1/4 cup household detergent,
1.6 liters 1 quart 5 percent sodium hypochlorite solution and 4.8
liters 3 quarts of warm water. Rinse thoroughly with fresh water.
(3)
Paint and Loose Particles:
Remove by wire brushing.
(4) Efflorescence: Remove by scraping or wire brushing followed
by washing with a 5 to 10 percent by weight aqueous solution of
hydrochloric (muriatic) acid. Do not allow acid to remain on the
surface for more than five minutes before rinsing with fresh
water. Do not acid clean more than 0.4 square meter 4 square feet
of surface, per workman, at one time.
[(5) Removal of Existing Coatings: For surfaces to receive
textured coating MPI 42, remove existing coatings including
soundly adhered coatings if recommended by textured coating
manufacturer.]
c.
Cosmetic Repair of Minor Defects: Repair or fill mortar joints
and minor defects, including but not limited to spalls, in
accordance with manufacturer's recommendations and prior to
coating application.
d.
Allowable Moisture Content: Latex coatings may be applied to damp
surfaces, but not to surfaces with droplets of water. Do not
apply epoxies to damp vertical surfaces as determined by ASTM D
4263 or horizontal surfaces that exceed 3 lbs of moisture per 1000
square feet in 24 hours as determined by ASTM F 1869. In all
cases follow manufacturers recommendations. Allow surfaces to
cure a minimum of 30 days before painting.
3.6.2
Gypsum Board, Plaster, and Stucco
a.
Surface Cleaning: Plaster and stucco shall be clean and free from
loose matter; gypsum board shall be dry. Remove loose dirt and
dust by brushing with a soft brush, rubbing with a dry cloth, or
vacuum-cleaning prior to application of the first coat material.
A damp cloth or sponge may be used if paint will be water-based.
SECTION 09900
Page 33
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