Engineering specific polyurethane sealant is a single/two-component moisture cured elastic sealing material, with core advantages of high elasticity, strong adhesion, weather resistance and wear resistance, and adaptability to large displacement joints. It is widely used in construction, road and bridge, curtain wall, municipal, industrial and other engineering scenarios.
1、 Core performance (engineering grade standard)
Type: Single component (direct use, wet curing), two-component (requires ratio, faster curing/higher strength)
Displacement capacity: ± 25% to ± 50% (suitable for expansion joints/settlement joints)
Elasticity: elongation at break 300% -800%, elastic recovery rate ≥ 70%
Strength: Tensile strength 0.4-1.2MPa, firmly bonded
Temperature resistance: -40 ° C to+120 ° C, no brittle fracture at low temperatures
Weather resistance: Outdoor aging resistance for 15-20 years, quality loss rate ≤ 7%
Surface drying/solidification: Single component surface drying for 1-4 hours, total solidification ≥ 3mm/24h
Adhesive substrates: concrete, stone, metal, glass, ceramics, wood, plastic, etc
2、 Engineering application scenarios (full coverage)
- Construction engineering
Sealing of expansion joints, settlement joints, and construction joints in concrete/precast slabs
Waterproofing of curtain walls, door and window frames, skylights, and metal roof joints
Balcony, swimming pool, bathroom, through wall pipe, equipment base anti-seepage
Underground garage, tunnel, pipe gallery, water tank sealing - Road and Bridge Municipal Administration
Expansion joints for highways/bridges, airport runways, and square floor grouting
Sealing of subway, pipe gallery, and culvert joints - Industry/Transportation
Car/Rail Transit Body, Container, Ship Sealing
Factory floor, clean room, and food workshop anti mold sealing (such as Sika 427)
Metal enclosure, gutter, and drain waterproofing
3、 Single component vs two-component (engineering selection)
table
Project single component polyurethane sealant two-component polyurethane sealant
Construction bucket ready to use, no need for mixing ratio, need to be mixed according to proportion, special glue gun is required
Curing moisture curing, slow curing in deep layers, fast curing in deep layers, good curing in deep layers
Displacement ± 25% – ± 35% ± 35% – ± 50%
Medium to high strength, suitable for heavy loads
Suitable for small and medium-sized joints, maintenance, rapid construction of large joints, heavy loads, and long-term water immersion
4、 Mainstream products and brands (commonly used in engineering)
Sikaflex-425 (floor), 427 (mildew proof), 221 (universal)
3M: 540 (curtain wall/metal), 550 (high modulus)
Jishibo: Silcor LM PU (Building/Waterproof)
Domestic: Silane modified PU, single component sealant (for road and bridge applications)
5、 Construction Key Points (Must See for Projects)
Base treatment: clean, dry, free of oil stains, no looseness, and primer if necessary
Seam width: recommended to be 5-50mm, depth ≥ 1/2 of seam width
Backing: use closed cell foam rod to control the depth to prevent three side bonding
Temperature: 5 ℃ -35 ℃ Construction, avoid rainy/high humidity weather
Maintenance: Do not touch water before the surface dries, it can bear weight/test water after full solidification
6、 Selection and avoidance of pitfalls
Select based on displacement capability: low zone ± 25%, high zone/large temperature difference ± 35% – ± 50%
Select by environment: choose weather resistant for outdoor use, water resistant for soaking, FDA certified for food area
Standards: Implement GB/T 13477 and JC/T 482
Avoiding pitfalls: Low price adhesives are prone to cracking, poor adhesion, and poor weather resistance, so engineering grade brands are preferred