MIL-HDBK-1110
5.14
Concrete Swimming Pools. Concrete swimming pools
require periodic painting to keep them watertight and attractive.
Even fiberglass-reinforced plastic pools may require refinishing
to restore them to an acceptable appearance should they fade or
chalk significantly. Chlorinated rubber coatings (e.g., TT-P-95,
Type I) have been used effectively for many years for lining
pools. Although these coatings are high in VOCs (solvent
content), they have received a temporary exemption for coating
concrete pools in most locations with VOC limitations. Epoxy
coatings perform well on interior concrete pools, but some of
them chalk to such an extent, even underwater, that the water is
clouded in exterior pools. Waterborne pool coatings have not
proven to be durable.
a) Exterior pools are usually coated in the spring
before the swimming season when the temperature is between 50 and
80 degrees F. New concrete pools should be allowed to cure at
least 2 months before painting. The first step in preparing
concrete pools for painting is to make necessary repairs:
(1)
Remove loose concrete
(2)
Repair small cracks and holes
(3)
Repair large cracks and spalls
b) Repair small cracks and holes with a non-shrinking
patching compound. Cracks greater than 1/2 inch and spalls
should be repaired with cementitious material (e.g., a mix
containing two parts of clean, hard, sharp sand to one part of
Portland cement). The repair area should be thoroughly wetted
and enough water added to the mix to make a heavy paste.
c) After repairs have been made, any efflorescence or
laitance on the surface of the concrete should be removed by
brushing with a dry bristle brush, treating with 5 to 10 percent
muriatic (hydrochloric) acid, and rinsing with clear water.
Mildew should be removed as described in par. 5.18, and body oils
should be removed with trisodium phosphate or other detergent.
Any deteriorated old paint should be removed by wire brushing or
careful light abrasive blasting.
d) Application of chlorinated rubber paint should
occur in two coats to completely dry surfaces. The first coat is
best applied by brush to fill the concrete pores, but the second
can be applied by roller or spray. A minimum of 24 hours should
occur between coats to ensure complete evaporation of solvent
from the first coat. Painting of individual walls should
continue until completion to avoid lap marks where the work was
interrupted. Because the coating dries very fast, it may be
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