The Silicoflex Joint Sealing System was developed as a direct response to bridge owners asking for a higher quality, longer lasting, more universal joint sealing system

The Silicoflex System consists of an inverted ‘V’ shaped, preformed, extruded silicone rubber seal, with a single component silicone locking adhesive and a primer. Two beads of silicone locking adhesive are used; one above and one below the silicone rubber seal to ensure a tenacious, water-tight and continuous seal.  The system also comes with a single part silicone adhesive and a primer which creates a tremendously strong bond to the joint header.  Silicoflex is used in both new construction with an armoring system or without. The system has been used heavily in bridge preservation activities and has been installed on hundreds of bridges and highways worldwide.

By selecting one of four individual Silicoflex glands any joint ranging from 0.5″ to 6.5″ will be sealed.  The ability of the system to bond to new or existing steel extrusions, concrete, or elastomeric concrete joint headers makes it the most versatile system on the market today with an incredible track record of performance and longevity on existing installations that are over 20 years old on major highways across the US.

Silicoflex was installed on the approaches to the Golden Gate Bridge


Low Stress Design

During normal cyclic movement, the Silicoflex seal is not in tension due to its folded inverted “V” shape.  This reduces stress on both the seal and the adhesive and eliminates the possibility of cohesive failure typically found in field molded sealants.

Large Movement Range

Silicoflex is manufactured in three different sizes which cover the full range of movements typical of single cell joint openings.

Temperature Insensitive

Silicoflex will remain flexible in almost any environment.  The material stability temperature range for Silicoflex is -60° F to +350° F.

Ultraviolet Radiation and Ozone Resistant

The Silicoflex seal is comprised of an inorganic base silicone, which means it is highly resistant to the damaging effects of ultraviolet radiation and ozone attack.  This resistance is far superior to organic rubbers commonly found in other joint sealing systems which degrade due to U.V. exposure.


Silicoflex will bond equally well to steel, concrete and elastomeric or polymer concrete surfaces.  Silicoflex can also be used to reseal failed strip seal joints and works well with irregular, tapered and spalled joint openings.  These features make Silicoflex ideal for maintenance and retrofit projects.


Silicoflex applications installed in the mid-1990’s are still performing effectively to this day.

Fast and Simple Installation

After sandblasting (if necessary) and priming, installation time is about 15-20 minutes per lane.  30 – 60 minutes after the installation is complete, the lane can be reopened to traffic.

Maintenance Friendly

In the event of a puncture, Silicoflex can be easily repaired using the silicone based locking adhesive.  With more severe damage, locally damaged pieces can be removed and new pieces can be spliced in.

Debris Friendly, Self Cleaning Design

The inverted “V” shape directs debris to the edges of the seal where it is bonded and fixed.  During cycling, debris is channeled upwards thereby reducing the chance of punctures.  Other systems with “V” shaped seals direct debris towards the unsupported center, making it much more susceptible to punctures from debris.

Field Spliceable and Directional Changes

If required, the Silicoflex gland can be bonded to itself by using the same silicone locking adhesive.  This permits installations lane by lane or rapid custom tailoring of the gland to go up and around curbs and parapets.

Installation Steps

Ease of Installation is a hallmark of the Silicoflex Joint Sealing System

Traffic is usually allowed in about an hour

Installation Instructions PDF

Installation Video

⇒For newly primed steel joint installations, wipe vertical faces of joint clean with a rag saturated in denatured alcohol – no sandblasting is necessary. For new concrete joint installations, roughen concrete surface and wipe vertical faces of joint clean with a rag saturated in denatured alcohol. Roughening can be done by sandblasting, wire brushing or other mechanical methods approved by RJ Watson. For joint seal replacements to existing joints, sandblast the vertical faces of the joint and wipe clean with a rag saturated in denatured alcohol.

⇒Mix together A and B components of Primer using a hand or drill mixer. Apply to the vertical joint interfaces.

⇒Unroll Silicoflex seal, place adjacent to joint opening and clean the seal with a rag saturated with denatured alcohol.

⇒Using a jumbo size (29 oz) caulking gun, place a 1/2” diameter bead of Silicoflex Locking Adhesive to both sides of the vertical face of the joint. This bead of adhesive should be placed at least 1” below the top of the joint elevation.

⇒Insert the Silicoflex seal into the joint, initially placing it above the first bead of locking adhesive. Gently ease the Silicoflex seal downward while maintaining contact of the sides of the seal to the joint header. Position the Silicoflex seal to the proper depth, which is when the top of the seal is at least 1.0” below top of road surface.

⇒Apply a second bead of locking adhesive along each side of the Silicoflex seal, to the top of the serrations, and no higher. This second bead of adhesive should be in contact with the Silicoflex seal and the joint face.

⇒The locking adhesive must be ‘tooled’ at least twice with a tongue depressor to ensure complete contact with the joint face.

⇒Allow 60 minutes before allowing traffic over a newly installed Silicoflex seal, unless directed otherwise by an approved representative. Vertical curbs, directional changes and field splices require the Locking Adhesive as a bonding agent.

Installation Conditions

The recommended minimum air/surface temperature to install Silicoflex is 40° F. The joint surface must be completely dry before installing Silicoflex. Silicoflex should not be installed immediately after precipitation or if precipitation is forecast for the day. Joint preparation and installation of Silicoflex must be done during the same day. Traffic must not be allowed to pass over a sandblasted and primed joint. R.J. Watson employs qualified technical representatives who can provide hands-on training for installers of Silicoflex. It is recommended that this service be used by first time installers. Please call our office to schedule a technical representative to be at your jobsite.

Silicoflex Sizing Models

RJ Watson is located outside of Buffalo, NY and  has a state of the art 70,000 square foot facility for engineering, fabrication and testing of bearings, joints and other structural devices

Testing Video

RJ Watson provides at no cost or obligation engineering proposal on any project where you are interested in evaluating the benefits of the RJ Watson product line

No Cost/No Obligation Estimates

Our staff of experienced engineers will assist you with your proposals and will work within your tight time constraints.

RJ Watson’s in house operations include a fabrication shop with overhead cranes, heavy lifting capacities, certified welders, weld positioners, media blasting, machine shop and state of the art testing facility.

Project Updates

Franklinville Bridge, NY Rehab

Franklinville Bridge, NY Rehab

December 3, 2018

Large Displacement Silicoflex Joint Test

Large Displacement Silicoflex Joint Test

November 28, 2018

Abraham Lincoln Bridge over Ohio River

Abraham Lincoln Bridge over Ohio River

November 28, 2018

Francis Scott Key Bridge Joint Replacement

Francis Scott Key Bridge Joint Replacement

November 28, 2018

US 701 Joint Seal Installation – Georgetown, SC

US 701 Joint Seal Installation – Georgetown, SC

November 27, 2018