A complete introduction to PU sealant for concrete expansion joints
PU polyurethane sealant is a mainstream specialized sealing material for concrete expansion joints, deformation joints, and settlement joints. It relies on high elasticity, strong concrete bonding, wear resistance, and rolling resistance, and is widely used for waterproof sealing of concrete joints in roads, bridges, water conservancy, floors, and roofs.
1、 Two major categories of products (selection core)
- Single component PU sealant (small joints on construction sites, easy construction)
Single component sausage with PU adhesive
Curing: Absorb moisture from the air and cure at room temperature. Apply glue directly after opening the cylinder, without the need for mixing ratio
There are two types of forms:
Paste non sagging type: facade wall, vertical expansion joint, roof grid joint
Self leveling type: horizontal road surface, floor, wide expansion joint (5-25mm), automatic leveling and joint filling
Advantages: fast construction and simple tools; Disadvantages: Thick seams and slow deep curing, completely dry out in 3-7 days
Applicable: community roads, indoor flooring, roof partition joints, small building expansion joints - Two component PU sealant (for large-scale projects, water conservancy/road and bridge heavy loads)
Two component AB barrel PU adhesive
Mix ratio: A main agent: B curing agent=10:1, mix evenly by electric stirring before use, and use up within 30 minutes after mixing
Curing: Chemical reaction for deep and rapid curing, thick seams without foaming, stronger waterproof stability
Advantages: Stretching displacement ability ± 50%, waterproof durability, water bubble resistance, high tensile strength; Special for water conservancy, dams, box culverts, and bridges
Applicable: highway bridges, channel reservoirs, subways, basement settlement joints, large hydraulic concrete expansion joints
2、 Core performance (adapted to the expansion and contraction requirements of concrete)
Super strong bond strength of concrete
Penetrating concrete capillary pores to form mechanical interlocking, it is not easy to peel off without primer, which is superior to silicone adhesive; Construction can still be carried out after wet base treatment
High elasticity to adapt to stretching and deformation
Elastic recovery rate ≥ 90%, able to withstand ± 25%~± 50% joint displacement; Repeated stretching without cracking during winter shrinkage and summer expansion; The maximum elongation rate can reach 800%
Wear resistant and resistant to vehicle crushing
High mechanical strength and wear resistance, preferred for heavy-duty roads and parking lots; Common for asphalt and concrete pavement
Temperature resistance, water resistance, acid and alkali resistance
Stable use -40 ℃~80 ℃, low temperature in northern winter does not cause brittle cracking; Long term immersion in water and mild acid-base environment without failure; Waterproof and anti-seepage measures to prevent groundwater infiltration
Brushable paint decoration
After complete curing, it can be coated with cement paint and exterior wall paint, which is aesthetically pleasing and uniform; The inability of silicone adhesive to paint is a clear weakness
shortcoming
Ordinary PU is prone to slight yellowing after long-term exposure to sunlight; High UV outdoor long-term scenes can be protected with weather resistant modified PU or a topcoat