Page 303 - Construction Waterproofing Handbook

EXPANSION JOINTS 6.7
TABLE 6.1 Sealant Expansion Joint Properties

Advantages Disadvantages
Compatibility with waterproofing systems Minimal movement capability
Seamless application Protection recommended
Ease of terminations Not for excessive wear areas

T-Joint systems
A T-joint system is a sealant system reinforced with metal or plastic plates and polymer con-
crete nosing on each side of the sealant. This system derives its name from a cross section
of the joint, which is in the shape of a T. Figure 6.4 shows a typical T-joint configuration.
The basic T-joint consists of several components, including:
● The sealant, usually urethane
1
● The reinforcement plate, 8-in aluminum or plastic reinforcement
● The bond breaker tape, which prevents three-sided adhesion to reinforcement
● The epoxy or polymeric nosing for attaching to substrates
Whereas sealant joints are recommended only for up to 1 in widths, T-joint design allows
for greater widths by adding reinforcement at both bottom and sides. With T-applications,
joints as wide as 12 in (excluding nosing) are used. Design width of sealant in T-joints is rec-
ommended at five times anticipated movement, versus four times with regular sealant joints.
This provides an additional safety factor for these size joints. Manufacturers require that joint
width be not less than 3–4 in.
The T-system modifies a regular sealant joint to withstand the abuse and wear encoun-
tered in traffic-bearing horizontal joints. The metal plate reinforces the soft sealant during
loading by automobiles. Nosings provide impact resistance and additional adhesion prop-
erties. It is recommended that this nosing extend approximately 8 in above the sealant
1
material and be sloped toward the sealant, to prevent damage from automobiles and other
heavy equipment.

FIGURE 6.4 T-expansion-joint detailing.