771.11 Bridge Joint Sealing - Silicone

Code: R321

Silicone bridge joint sealing is done to prevent dirt, debris, and chlorides from deteriorating the deck and supporting bridge members. The work is done late April thru early June and mid September thru early November, weather permitting with temperatures between 55 to 80 degrees. No significant precipitation within 36 hours prior to installation.

General Note: Sealing of concrete-to-concrete bridge approach or deck joints with silicone material should only be done during moderate temperatures. Use silicone products only at concrete or steel joints, which are in good condition or in conjunction with Silspec 900 PNS.

Use silicone when one of the following conditions is present in a concrete-to-concrete joint:

1. Joints which are one inch or less in width that are very clean to work with and would require very little hand or mechanical cleaning to prepare. Use DOW890-SL.

2. Joints greater than one inch in width but less than 2 ½ inches wide, that are very clean to work with and would require only minimal mechanical or hand cleaning to prepare. Use DOW 902-RCS.

Materials

DOW 902-RCS, DOW 888, or 890-SL, Backer rod, Primer (Note: refer to Dow Corning table for appropriate primer required.)

Procedures

1. Perform any repairs to joint, as required, before attempting to do any silicone work. It is vital that concrete faces are in sound condition or the silicone will pull off the weak concrete. Joints repaired with concrete products shall be allowed to cure for fourteen days. Joints repaired with epoxy products shall be cured in accordance with manufacturer’s recommendations.

2. Using hand tools or other equipment as required, clean out as much of the existing old sealant and debris as possible to a depth three times the width of joint.

3. Sandblast the joint faces with black beauty or other clean abrasives.

4. Inspect vertical faces to assure that they are immaculately clean and no residue is present.

5. Prime the joint faces with recommended material and allow to cure as per manufacturer’s guidelines.

6. Install appropriate size backer rod to a completely snug fit but not over compressed. Installation of backer rod should be to a depth one half the joint width, plus an additional one half inch but not greater than 1 ¼” total depth below the roadway surface.

7. Install silicone with Bazooka gun for 902 or hand caulk gun for 890 to one half inch below roadway.

8. Thoroughly clean out Bazooka gun as recommended by manufacturer after completing installation.

Clean out as much of the existing old sealant and debris as possible to a depth three times the width of joint.	Sandblast the joint faces with black beauty or other clean abrasives.
Prime the joint faces with recommended material and allow to cure as per manufacturer's guidelines. Install appropriate backer size rod to a completely snug fit but not over compressed.	Install silicone with Bazooka gun for 902 or hand caulk gun for 890 to one-half inch below roadway.
Thoroughly clean out Bazooka gun as recommended by manufacturer after completing installation.