Repair of Leaking Expansion Joints

Many of you reach out with questions about repairing leaking expansion joints in various construction structures. Recently, I received the following message:

“Hi ?ukasz, is there a type of resin that can be injected into an expansion joint to prevent water ingress into a car park?”

I am happy to answer because leaking expansion joints are a common issue affecting many facilities. Depending on the location of the expansion joint—whether it’s in a foundation slab, wall, ceiling, or column—the repair methods may vary. Access to the joint (from one or both sides, or from above or below) also impacts the selection of the appropriate technique.

Diagram Key

1. (0) Joint Cleaning - essential preparatory step before starting repairs.

2. (1) Minimum Depth of ResinBau AcrylicGel + Polymer Fill - should be 120 mm for effective waterproofing.

3. (2) Correctly Executed Drill Holes - allow even injection and process control.

4. (3) Polypropylene Tubes - used to limit gel leakage during injection.

5. (4) Fast-Setting Mortar Seal - temporary protection for the lower part of the joint.

6. (5) Acrylic Gel Injection - the primary stage of filling the joint with waterproofing material.

7. (6) PU-40 Polyurethane Sealant - final joint seal to prevent gel drying.

General Guidelines for Expansion Joint Repair

Regardless of the type and location of the expansion joint, thorough cleaning (0) is a critical step:

? Removal of insulation materials such as styrofoam or mineral wool.

? Elimination of loose fragments and contaminants.

? Surface preparation to ensure proper adhesion of repair materials.

Expansion Joint in the Foundation Slab

For a leaking expansion joint in a foundation slab, we can use a gravity-pouring method after cleaning:

1. Prepare the acrylic gel with polymer (e.g., ResinBau AcrylicGel + Polymer) with a short setting time (adjustable with B2 additive).

2. Pour the first layer from above to reduce the consumption of injection gel.

3. Pour successive layers of gel with a longer setting time until the joint is completely filled.

4. Seal the joint with PU-40 polyurethane sealant (6) to prevent dry air access, which could shrink the gel on the surface.

Important Note: The minimum thickness of the acrylic gel should be 120 mm (1) to ensure an effective waterproof barrier.

Ceiling Joint with Access Only from Below

If we are dealing with a ceiling joint accessible only from below (e.g., with a garden above without excavation access), the procedure is slightly different:

1. Drill injection and observation holes (2) in appropriate places and at different heights.

2. Introduce polypropylene tubes (3) into the joint to limit gel leakage during injection.

3. Temporarily seal the lower part of the joint with a fast-setting mortar like ResinBau CrackOn.5 (or mounting foam as a last resort) (4).

4. First injection of acrylic gel with a short setting time to create a barrier for subsequent layers.

5. Further injection of gel with a standard setting time until material appears in observation packers (5).

6. Remove the temporary seal (4) and seal the joint with PU-40 polyurethane sealant (6) to prevent the gel from drying out.

Wall Expansion Joint

For a wall expansion joint, the procedure depends on the level of access:

Access from Both Sides:

? The process is similar to the ceiling procedure, but conducted from both sides of the wall.

? Clean the joint, drill injection holes, and insert polypropylene tubes.

? Inject acrylic gel sequentially, monitoring the joint filling.

Access from One Side:

? The procedure is analogous, but all work is done from one side.

? Particular attention should be paid to monitoring the joint filling with gel.

Summary

I hope this information helps you with effectively repairing leaking expansion joints. Keep in mind that each case is unique and may require a slightly different approach. However, thorough cleaning and preparation of the joint, along with the use of appropriate materials and techniques, are essential.

PS. If the expansion joint contains rubber seals or other embedded elements, they may assist in guiding the joint. Evaluate whether they can be used in the repair and plan if the injection should be done before, through, or behind the seal.

Thank you for your attention. In the near future, improved drawings and educational materials, including 3D models, will be available to further aid in understanding the repair process. If you have questions or need additional information, feel free to reach out.

Additionally, in the near future, more interesting injection calculators will also be available on the website www.resinbau.com.

Special thanks to the Hammpack? and Resinbau brands, as well as the distributor of resins and accessories, pakery.pl.

Attachments:

Technical Data Sheet for ResinBau AcrylicGel