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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.
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.
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:
Yes, it is formulated for new construction, repair, and remedial applications in concrete to concrete and concrete to asphalt pavement joints. Its self-leveling nature and rapid skin-over time allow for quick re-opening of roadways.
No, primer is not required for Portland cement concrete and asphalt substrates. This simplifies application and reduces both material and labour costs on site.
DOWSIL™ 890-SL is an ultra-low modulus sealant, critical for sealing asphaltic paving materials with low tensile strengths. This characteristic minimises strain on the joint face, reducing the risk of failure.
Yes, it offers a movement capability of +100% extension and -50% compression. This ensures the seal remains intact under significant expansion and contraction, as tested by ASTM C 719 for 10 cycles with no failure.
| Application | Key benefit | Primary trades |
|---|---|---|
| Sealing concrete to concrete pavement joints | Provides durable, flexible seals with 100% extension and 50% compression capability, resistant to weather and UV exposure. | Paving contractors, civil engineers |
| Sealing concrete to asphalt pavement joints | Ultra-low modulus design minimises strain on low tensile strength asphalt, preventing early joint failure. Achieves unprimed adhesion. | Road maintenance crews, civil engineers |
| New construction, repair, or remedial joint sealing | Self-leveling application eliminates tooling, flowing into irregular joints and spalls. Rapid skin-over (less than 1 hour) allows quick traffic access. | Infrastructure developers, repair contractors |
| Sealing joints that require quick return to service | Fast skin-over time, typically one hour or less, significantly reduces road closure times, minimising disruption. | Public works departments, road maintenance |
| Joints exposed to fuel spills or harsh weather | Offers short-term fuel resistance and proven weather/UV resistance for over 5,000 hours, extending joint lifespan. | Highway engineers, airport maintenance |
Ensure all joint surfaces are clean, dry, and free of dust, oil, moisture, or loose materials. Remove old sealant and clean to full depth using compressed air or mechanical tools.
Use a wire wheel or abrasive grinder to expose clean concrete or asphalt joint edges. Recommended for heavy contamination or remedial work.
Use oil-free compressed air to remove fine particles and moisture from saw-cut joints. Ideal for new concrete or routine re-seals.
Select a closed-cell backer rod with a diameter 25% larger than the joint width. Insert it to proper depth to control sealant depth and prevent three-sided adhesion.
Install rod to a depth that allows for 6–13 mm of sealant, depending on joint width. Refer to Dow’s table for size-specific recommendations.
Use dual-layer or larger rods to maintain consistent sealant thickness and recess even in uneven joints.
Apply Dowsil 890-SL directly into the joint using a bulk gun, cartridge, or pump setup. The product self-levels, filling the joint evenly without tooling.
Use 857 mL plastic cartridges with a heavy-duty dispensing gun. Ideal for smaller patchwork and on-site repairs.
Use pneumatic or electric pump to dispense from 17 L pails or 189 L drums for large-scale joint sealing projects.
Under normal conditions (25°C, 50% RH), the sealant will become tack-free within 1 hour and cure fully in 21 days. Light traffic may resume once the sealant skins over.
Allow at least 1 hour before light traffic exposure. Use signage or barriers to protect fresh joints.
Extend cure and skin time accordingly. Avoid application below -6°C or above 38°C surface temperature.
WARNING! Causes serious eye irritation. Harmful to aquatic life with long lasting effects.
Use chemical goggles for eye protection. For skin protection, use chemical-resistant gloves classified under AS/NZS 2161.10, such as Butyl, Nitrile/butadiene rubber, or Neoprene. Use protective clothing chemically resistant to this material.
Use local exhaust ventilation or other engineering controls to maintain airborne levels below exposure limits. General ventilation may be sufficient for most operations, but local exhaust may be necessary for some.
Store in original, unopened, properly labelled containers at or below 32°C (90°F), locked up and in accordance with national regulations. Do not store with strong oxidising agents. Dispose of contents and containers to an approved waste disposal plant, in compliance with all local, state, and federal regulations.
Proper substrate preparation is essential for reliable bond strength and long-term joint performance with DOWSIL™ 890-SL.
Surface prep: Substrate must be clean, dry, and free from loose material, dust, oil, grease, or any other contaminants. Old sealants should be removed. Joint surfaces must not be wet or damp.
Primer: Not required. DOWSIL™ 890-SL exhibits unprimed adhesion to Portland cement concrete.
Surface prep: Substrate must be clean, dry, and free from loose material, dust, oil, grease, or any other contaminants. Joint surfaces must not be wet or damp. Its ultra-low modulus is specifically designed for the low tensile strength of asphaltic materials.
Primer: Not required. DOWSIL™ 890-SL exhibits unprimed adhesion to asphalt.
| Property | Value |
|---|---|
| Color | Dark gray |
| Flow | Pass (Smooth, level) |
| Extrusion Rate Minimum | 231 mL/min |
| Tack Free Time | Pass (5 hours max) |
| Heat Aging | 0.97% |
| Durometer Shore 00 | 41 |
| Specific Gravity | 1.26–1.34 |
| Ultimate Elongation | 1400% |
| Tensile Stress at 150% | 9 psi |
| Effects of Accelerated Weathering | Pass (5,000 hours) |
| Resilience | 77% |
| Joint Movement Capability (+100% / -50%, 10 cycles) | No failure |
| Flexibility Range | -29 to 149°C |
| Physical State | liquid |
| Odor | Fishy |
| Boiling Point | > 35 °C |
| Flash Point | 100 °C (Pensky-Martens closed cup) |
| Relative Density (water = 1) | 1.3 |
| Water Solubility | insoluble |
| Kinematic Viscosity | 300000 mm2/s at 25 °C |
Here are some common examples on where Dowsil 890-SL Silicone Joint Sealant used by our customers.
