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Dowsil 888 is a non-sag, one-part silicone joint sealant purpose-built for concrete pavement joints where movement, weather exposure, and durability are constant challenges. With proven movement capability of +100% extension and -50% compression, it flexes with slab movement instead of tearing apart—so your joints stay sealed through seasonal shifts and heavy use. It extrudes in conditions from cold mornings to extreme heat, giving you job-site flexibility without fighting the material. The result is predictable performance, fewer failures, and no costly callbacks when sealing critical pavement joints first-time-right.
Potential Outcome: Poor adhesion leading to sealant debonding and joint failure.
Adheseal Best Practice: Only apply to clean, dry, frost-free concrete. Proper prep ensures full adhesion and predictable performance—no rework later.
Potential Outcome: Three-sided adhesion causes stress build-up and tearing.
Adheseal Best Practice: Install correct backer rod and follow depth ratios. This allows proper movement and prevents failure—first-time-right sealing.
Concrete slabs expand and contract constantly. Standard sealants crack or debond, leading to water ingress and joint deterioration.
Dowsil 888 flexes with slab movement thanks to its high elongation and movement capability. Apply into correctly prepared joints with backing rod to allow full movement. Success means durable, sealed joints that hold under real traffic and weather conditions.
Keep sealant recessed 9–13 mm below surface as per joint design. This protects the seal and maintains performance after surface grinding.
Existing joints are irregular, with minor spalling and inconsistent widths—hard to seal properly with rigid materials.
Dowsil 888 accommodates non-uniform joints while maintaining adhesion and flexibility. Its non-sag consistency allows controlled placement even in difficult repairs. Success means reliable sealing without needing perfect joint geometry.
Ensure old sealant is fully removed and joint is clean before installing new material. This prevents contamination and ensures long-term bond strength.
Dowsil 888 is used for sealing concrete pavement joints. It provides flexible, weather-resistant sealing that handles joint movement and prevents cracking or water ingress.
Dowsil 888 handles +100% extension and -50% compression. This high movement capability allows joints to expand and contract without failure, delivering predictable performance.
Dowsil 888 does not require a primer on clean Portland cement concrete. This unprimed adhesion speeds up application and reduces labour without compromising bond strength.
Dowsil 888 can be extruded from -20°C to 49°C. This wide application temperature range keeps you working across varied site conditions without delays.
Clean the joint thoroughly using wire brushing and high-pressure air. Remove all dust, laitance, curing compounds, and contaminants. Ensure the substrate is dry and frost-free before applying the sealant.
Allow concrete to cure properly. Saw-cut joints and remove dust with compressed air. Ensure the surface is free of all contaminants.
Grind and remove old sealant. Clean with abrasive method and air blowout. Ensure surface is recessed and uniform before installation.
Insert closed-cell backer rod to control sealant depth and prevent three-sided adhesion. Select appropriate diameter to allow compression during insertion.
Place backer rod to a depth that allows sealant thickness of 6–13 mm depending on joint width. Use joint width-to-depth ratio of approximately 2:1.
Account for expected grinding depth — place rod slightly deeper (up to 12.7 mm) so final profile sits correctly below the surface.
Dispense DOWSIL™ 888 using a manual, pneumatic, or bulk pump gun. Apply in a continuous motion to avoid air entrapment.
Cut nozzle to match joint width and extrude steadily. Tool immediately to avoid skin formation.
Use an air-powered system for large jobs. Maintain consistent pressure and flow rate above 72 mL/min.
Tool the sealant to form a concave profile recessed 9.5 to 12.7 mm below the slab surface. Protect from moisture for 8–24 hours. Clean tools using solvent or mechanical wiping before curing completes.
Allow 21 days at 25°C / 50% RH for full cure. Cooler temps will extend curing time.
Wipe uncured material using xylene or suitable solvent. Do not use water-based cleaners.
DOWSIL™ 888 must only be applied to clean, dry, frost-free surfaces. It is not suitable for use in permanently immersed joints or those exposed to standing water prior to cure.
Do not apply to bituminous or oily substrates. For such joints, consider alternative polyurethane-based or hybrid sealants suited to flexible pavements.
To maintain proper movement capability, always install a backer rod or bond-breaker tape to prevent adhesion on three sides of the joint.
Store in original, sealed packaging below 32°C. Use within the shelf life printed on packaging (typically 12 months from manufacture). Protect from freezing.
Contains moisture-curing silicone polymers. Emits methanol vapours during cure. Use in well-ventilated areas. Avoid inhalation or skin contact with uncured product.
Wear nitrile gloves, safety glasses, and suitable protective clothing. In enclosed areas, use adequate respiratory protection if ventilation is poor.
Dispose of uncured product and contaminated materials according to local environmental regulations. Do not pour into drains or watercourses.
In case of skin contact, wash with soap and water. For eye exposure, rinse immediately with water and seek medical attention. Refer to SDS for detailed guidance.
Ensure concrete is clean, dry, and frost-free. Remove dust, debris, oils, and old sealant residues before application.
Dowsil 888 adheres directly to properly prepared concrete, reducing prep time and improving job efficiency.
Here are some common examples on where Dowsil 888 Silicone Joint Sealant used by our customers.
| Property | Value |
|---|---|
| Base Chemistry | One-part non-sag silicone |
| Colour | Gray |
| Movement Capability | +100% extension, -50% compression |
| Ultimate Elongation | ≥1000% |
| Shore A Hardness | 15 |
| Specific Gravity | 1.48 |
| Skin Formation Time | ≤1 hour |
| Cure Time | 21 days |
| Application Temperature | -20°C to 49°C |
| Extrusion Rate | ≥72 mL/min |
| Standards Compliance | ASTM D5893 Type NS, FAA P-605, SS-S-200E, EN 14187-5 |
| UV Resistance | Pass 5000 hours accelerated weathering |
| Resilience | 77% |
