Page 66 - Construction Waterproofing Handbook

2.30 CHAPTER TWO

FIGURE 2.37 Patching of concrete substrate prior to waterproof-
ing application. (Courtesy of Vandex)

containers and added to the sand-and-cement mixture. Products are mixed in accordance
with manufacturers’ recommendations, adding only clean water.
Typically, cementitious systems are applied in two coats after the initial preparatory
work is complete. First coats may be proprietary materials only. Second coats are usually
the chemical or metallic materials within a cement-and-sand mixture. Third coats are
applied if additional protection is necessary. They consist only of sand and cement for pro-
tecting exposed portions or adding texture. Acrylic systems often require a reinforcing
mesh to be embedded into the first-coat application.
Thickness of a system depends upon the sand and cement content of the coatings. The
systems are applied by trowel, brush, or spray. Refer to Fig. 2.38. Certain systems are dry-
broadcast over just-placed concrete floors to form a waterproofing surface integral with the
concrete.
This method is referred to as the dry-shake application method. Broadcasting powder
onto green concrete is followed by power troweling to finish the concrete and distribute
the chemicals that are activated by the concrete slurry. This method should not be used for
critical areas of a structure subject to water head, as it is difficult to monitor and control.
Refer again to Fig. 2.36.
To protect exposed floor applications, a 2-in concrete topping, carpet, tile, or other fin-
ish is applied over the membrane. Walls can be finished with a plaster coating or furred out
with adhesively applied drywall or other finish systems.
These systems require proper curing of the cementitious waterproof coating, usually a wet
cure of 24–48 hours. Some systems may have a chemical additive to promote proper curing.
These systems do not withstand thermal or structural substrate movement. Therefore they
require special detailing at areas that are experiencing movement, such as wall-floor intersections.