Page 278 - Construction Waterproofing Handbook

SEALANTS 5.37
designed, improper installation will lead to failures. Successful installation depends on
several steps, including:
● Joint preparation
● Priming
● Installation of backer rod or backing tape
● Mixing, applying, and tooling of sealant
Of these steps, the most common problem and most widely abused installation step is
joint preparation. All remaining installation steps depend on how well this first step is
completed. If joints are not properly prepared, regardless of how well joints are primed and
sealed, materials will fail.

Joint preparation
The most common joint preparation problems arise when joints are not cleaned or when
contaminated and incorrect solvents are used. All joint contaminants must be removed and
joints must be dried before sealant and primer application (Fig. 5.33).
To clean a joint, two rags are necessary—one rag to wet a joint with solvent, the other
to wipe contaminants from the joint while at the same time drying it. Using a single sol-
vent rag will smear the contaminants in a joint. Continually dipping the same rag in a sol-
vent will contaminate the entire container of solvent.
All loose mortar and aggregates must be removed, since sealant will only pull loose
material away from substrates when the joint moves. Other contaminants, such as water-
proofing sealers, form-release agents, oils, waxes, and curing agents, must be removed.

FIGURE 5.33 Preparation of substrate joint prior to applying sealants. (Courtesy of
SWRI)