Free movement and load transfer are both achieved by the installation of dowels.
Free movement joints allow for the horizontal movement of the slab caused by shrinkage and thermal effects. No free movement joints should allow relative vertical displacement of the panels. Free-movement joints which are going to be heavily trafficked should be of an armoured type to minimise damage to the joint.
Free-movement joints are usually provided between pours.
Formed Joint Free movement joints take a number of forms, the most common however is that of the formed/construction joints which allow the concrete floor to be laid in panels.
These joints also differ and can mostly be split into 3 common categories:
Dowelled free movement joints consist of steel dowel bars which are debonded from a panel on one side
Plate dowel free movement joints are similar to dowelled construction joints but instead of bars a plate placed horizontally in the slab is used.
Armoured Joints have either dowels or plate dowels for load transfer but also provide a steel arris to prevent/reduce damage to the floor from Materials Handling Equipment (MHE).
These systems usually include a leave in place formwork system. Another type of free movement joint is the sawn free movement joint. Debonded dowels on cages are placed in position prior to casting so that once the slab is cast cuts can be sawn into the slab to form a joint. As the dowel is deboned on one side of the joint there is no restraint to movement. These joint rely on the saw cut being placed in the correct position after casting once the concrete is in place they are not visible.
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