If you have heard a "ca-clink" while driving over a bridge, then you've probably come into contact with an expansion joint. What is the purpose of these structural components?

Structures are made to move. Often overlooked in project plans, expansion joints add to the overall integrity of structures by giving them the freedom to move. Without expansion joints, structures would eventually crack and fall apart over time.

For more than 70 years, Watson Bowman Acme has supplied in-house engineered and manufactured expansion joint solutions to projects across the world.

Learn More About Expansion Joints

An expansion joint can expand or become larger or more extensive. It can also do the opposite and contract by becoming smaller. When an expansion joint moves up and down, it is performing vertical displacement. Another force, lateral shear, slides the joint along a plane that is parallel to the direction of lateral force.

Forces that cause movement include temperature, soil-setting, creep and shrinkage, seismic activity, wind or traffic- weight displacement.

Materials change in size when exposed to heat, causing three different types of expansion: linear, area and volume.

The formula for thermal expansion is ΔL = αLΔT, where ΔL is the change in length L, ΔT is the change in temperature, and is the linear expansion coefficient, which varies slightly with temperature.

Expansion joints can be found in a variety of structures including bridges, parking structures and stadiums/ arenas, and commercial/ buildings.

Within buildings they are found in the roof, interior wall, exterior wall, ceiling or floor. For ideas on how to configure a combination of expansion joints, check out our Transition Library.

Expansion joints are commonly made out of metal (aluminum, stainless steel), rubber, foam or silicone.

An expansion joint cover is the prefabricated protective cover of an expansion joint, which also remains unaffected by the relative movement of the two joined surfaces.

Projects have requirements for movement, loading and aesthetic criteria. When planning to install an expansion joint solution, you want to consider the size of the gap opening, the path you want it to travel, traffic, fire rating, installation and maintenance. We also provide custom solutions.

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Periodic maintenance of expansion joint systems should be planned for and expected. Regular inspections and remedial repair of loose or damaged components is an important requirement for realizing long lasting performance. Check out our Inspection Services for help with maintenance.

Proper preparation helps for the best reparation success. A good, clean profile allows for material to flow into the pore structure and will ensure a positive bond once it cures.

At Watson Bowman Acme, we create expansion joint designs according to our customers' specific needs. All of our expansion joints are in-house engineered and manufactured, with quality control throughout the entire process.

Factory Trained Applicators install expansion joints within the parking and stadium market sector.

Our website gives you a window into all things expansion joints. On our Products pages you can find different Wabo solutions. You can contact us with your questions.