A chalice joint (Dutch: kelkvoeg) is a joint with a tapering, splayed shape that is wider on one side than the other — like a chalice or a triangle that widens towards the top. Because of this shape the jointing material (mortar or grout) can penetrate deep into the joint and anchor well, giving a strong connection.
How it works
Where an ordinary joint is the same width throughout, the chalice shape gives the chalice joint extra grip:
- Deep filling — the wide opening lets the jointing material run far inside.
- Anchoring — because the joint narrows inward, the hardened jointing material keys in (a form of positive locking).
- Strength — the larger amount and better bond make the connection stronger than a narrow, straight joint.
Application
- Precast concrete elements — the longitudinal joints between hollow-core slabs and other floor units are often chalice-shaped, so the poured grout ties the slabs into a single acting whole.
- Sheet materials — when joining, for example, gypsum fibre boards, a splayed joint is used to help the filler bond well.
Points to watch
- Clean the joint and dampen it (depending on the jointing product) before filling, so the grout bonds well.
- Fill the chalice joint completely; air voids weaken the connection.
- In floor fields the well-filled chalice joint provides shear transfer between the slabs.
Related terms
- Joint
- Hollow-core slab
- Lattice-girder floor
- Grout
- Mortar
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