Page 286 - Construction Waterproofing Handbook

5.44 CHAPTER FIVE

FIGURE 5.40 Proper positioning of nozzle when applying sealant. (Courtesy of SWRI)

capacity caused by the lack of material
applied to the sides of the substrate as
shown in Fig. 5.44.
These failures both occur in the expan-
sion mode. It is interesting to note that these
problems can likely be prevented if the
sealant is applied when the joint is completely
expanded, or in its widest width stage. This
typically occurs when the temperature is the
coldest to be experienced over the life cycle
of the joint. Sealant applied under this con-
dition will always be in the compression
FIGURE 5.41 Typical sealant joint detailing.
mode, when the substrate is pressing the
sealant material together.
Under this situation, poor application techniques are much less likely to produce
failures of the sealant material. The joint is constantly compressing the material, and
whether it is too thick or thin, the material can usually provide sufficient capabilities to
maintain an effective weathertight condition (Fig. 5.45). Often the sealants in the joint
under these conditions will bulge outward. This is not a sign of failure, (unless adhe-
sion or cohesion problems are evident), just that the sealant is under a compression
mode. This bulging should not cause problems unless at a horizontal condition subject
to foot or vehicular traffic that can damage the exposed sealant. In such instances the
sealant should be recessed when the horizontal joint is in a contracted state, as shown
in Fig. 5.46.