Dowsil 890-SL Silicone Joint Sealant

For concrete to concrete and concrete to asphalt pavement joints in new construction or remedial roadworks, Dowsil 890-SL Silicone Joint Sealant provides a cold-applied, self-leveling seal that accommodates extreme movement. Its ultra-low modulus is specifically formulated to protect asphaltic joint faces, which have low tensile strength, by minimizing stress on the joint interface during expansion and contraction.

How it works

Dowsil 890-SL is a one-part, cold-applied silicone that flows directly into standard, irregular, or spalled joints without requiring tooling. Upon exposure to atmospheric moisture, the material cures into an ultra-low-modulus silicone rubber that maintains flexibility from -20 to 300°F (-29 to 149°C). Because it achieves unprimed adhesion to both Portland cement concrete and asphalt substrates, it eliminates the labor and material costs of a priming step. The sealant is formulated to skin over in one hour or less under standard conditions, allowing pavement and roadways to be reopened to traffic quickly.

Numbers that matter

• +100%/-50% joint movement (ASTM C 719): High movement capacity to absorb expansion and compression cycles across varying temperatures without adhesive or cohesive failure.
• 1400% ultimate elongation (ASTM D 412): Extreme elasticity that prevents tearing under high tensile strain.
• 9 psi tensile stress at 150% (ASTM D 412): Ultra-low modulus performance to prevent the sealant from pulling away from weak asphalt joint faces.
• 1 hour skin-over time: Fast surface dry time under standard conditions to minimize road closure windows and traffic delays.
• -20 to 120°F (-29 to 49°C) extrusion range: Broad application temperature window allowing installation in freezing conditions through to high summer heat.

Where to use it

• Concrete to concrete pavement joints.
• Concrete to asphalt pavement joints.
• New construction, joint repairs, and remedial pavement maintenance.
• Irregularly shaped and spalled joint sealing.

Limitations

• Do not apply to wet or damp asphalt or concrete pavements.
• Do not install during inclement weather.
• Not recommended for continuous water immersion.
• Do not apply in totally confined spaces where the sealant is not exposed to atmospheric moisture for curing.
• Contact Dow prior to specifying or installing in airfield runway applications.
• Do not use in applications associated with spill containment areas of any kind.
• Not tested or represented as suitable for medical or pharmaceutical uses.

Joint design and installation

Proper joint design is required to prevent three-sided adhesion and ensure performance. The sealant must be recessed a minimum of 3/8 inch to 1/2 inch (9.53 mm to 12.7 mm) below the pavement surface. On road surfaces where grinding is anticipated at a later date, the sealant and backer rod must be installed deeper so the sealant remains recessed by approximately 3/8 inch (9.35 mm) after grinding is complete.

For standard shallow cuts, refer to the following joint width and depth specifications:

• 6 mm joint width: Sealant thickness 6 mm, backer rod diameter 9 mm, recessed 9 mm below surface, total joint depth 25 to 29 mm.
• 9 mm joint width: Sealant thickness 6 mm, backer rod diameter 13 mm, recessed 9 mm below surface, total joint depth 29 to 32 mm.
• 13 mm joint width: Sealant thickness 6 mm, backer rod diameter 16 mm, recessed 9 to 13 mm below surface, total joint depth 32 to 35 mm.
• 19 mm joint width: Sealant thickness 9 mm, backer rod diameter 22 mm, recessed 9 to 13 mm below surface, total joint depth 41 to 45 mm.
• 25 mm joint width: Sealant thickness 13 mm, backer rod diameter 32 mm, recessed 13+ mm below surface, total joint depth 57 to 60 mm.
• Joint widths greater than 25 mm (1 inch): Contact Dow for technical support before installation.