Why all wave-form concrete floor joints aren’t created equal.

1st February 2016

Why all wave-form concrete floor joints aren’t created equal.

The launch and international success of our Permaban Signature joint for concrete floors has helped the concept of ‘wave-form’ joints – properly called disruptive face joints – to gain strong acceptance in the market. 

The benefits of this style of joint are many.  Because there are no straight edges on the joint, vehicle wheels cannot drop between the two edges when they cross at 90⁰, and so there is no joint impact and therefore no joint damage.  This means wave-form joints will not cause the future maintenance headaches that straight joints can when used in challenging places.  No impact on the joint also means no impact on the vehicle, reducing untimely vehicle maintenance costs.  What’s more, drivers don’t experience the jolting which can lead to back pain and absenteeism costs.

Different products, concepts and shapes of wave-form joints are now available – yet there are important differences to note which demonstrate that not all wave-form joints are the same.

For example, some wave-form joints are designed as a flat metal plate attached to the top of a traditional joint – but these present five technical challenges during installation and use: 

  • how to ensure good concrete compaction beneath the plate, when it cannot be visually checked.  Poor compaction can lead to potential collapse of the joint;
  • how to fine-tune the plate to the floor level during installation. The width of a plate joint can give rise to significant elevational difference when installed just a couple of degrees out of alignment;
  • should the slab curl, plates cannot be ground back in to tolerance;
  • how to prevent the metal plate from deforming under the duress of traffic;
  • the unintended consequence of adding not one, but two straight joints at the sides of the plate, thus doubling the amount of maintenance that would have been needed had a straight joint been used. 

Other wave-form joints go a little deeper, yet extend only the partial depth of the slab, sitting atop a conventional flat divider plate.  This can create a point of joint weaknesses half way down the slab, which could in time affect the load-bearing of the floor around the joint area.

Lacking an integral dowel, twin overlapping wave form joints lose all load at a relatively small joint opening. Additionally, they lack the ability to prevent differential displacement between adjacent panels, particularly if curling is experienced.

Some wave-forms are created with a shallow angle, which means that when the joint opens beyond a few millimetres there is clear space created between the two wave edges.  This not only leaves space for vehicle wheels to drop between the edges and create an impact jolt (precisely what needs to be avoided), but it could also compromise the load transfer of the joint.

So when considering wave-form joints, remember to consider all the following (which are the things we took into account when creating Permaban Signature):

  • installation quality and integrity
  • load bearing and load transfer
  • potential joint width
  • hidden points of weakness below the surface
  • future maintenance

For more information about the performance and technical specification of Permaban Signature, speak to our technical sales team who will be happy to help.

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