Page 268 - Construction Waterproofing Handbook

SEALANTS 5.27
TABLE 5.3 Comparison of Common Sealant Properties

Precom-
Poly- Poly- pressed
Property Acrylic Butyl Latex sulfide urethane Silicone foam
Maximum joint 7 5 7 25 25 50 25
movement
capability, %
Weathering Good, Excellent,
resistance excellent Excellent Fair Good good Excellent Excellent
Recovery, % 25 Poor 75 80 90 100 100
Adhesion Good Excellent Fair Good Good Excellent Excellent
Joint design 12 20 12 6 4 4 *
(number of
times expected
movement)
Shrinkage, % 12 18 20 10 5 3 n/a
Tack-free time 72 24 1 72 72 3 n/a
(hours)
Water immersion No No No Yes Some No No
Paintable Yes Yes Yes No No No No
Primer required No No Some Metal, Horizontal Metal, No
cases masonry masonry natural
stone
Ultimate Low Low 450 1000 700 1600 Very
elongation, % low
Horizontal joints No No No Yes Yes No Yes
Modulus of
elasticity, lb/in 2 40 25 18 30 35 30 25
*Best in compression mode.

grades for use in preparing cracks in substrates before waterproof coating application.
They are used in small movement joints such as doors and window perimeters, thresholds,
and equipment penetrations.
Acrylic-based sealants do not require primers and have minimal surface preparation.
Their general ease of application is offset by low performance characteristics. These mate-
rials are not recommended in continually submerged joints or joints subject to vehicular or
foot traffic. (See Table 5.4.)

Butyl
Butyl sealants are produced by copolymerization of isobutylene and isoprene rubbers.
Butyls are some of the oldest derivatives to be used for sealant materials. However, tech-
nological advancements in better-performing sealants have now limited their use to glaz-
ing window perimeters or curtain walls with minimal movement.