A rebar chair is a product designed to provide increased concrete cover requirements from surfaces. It elevates rebar so that concrete cover is achieved. A rebar chair is a product used in the placement and formwork of concrete for helping to ensure that rebar is placed where it needs to be in a concrete element.
Rebar Chairs and Concrete Cover
A rebar chair helps to increase the concrete cover for concrete reinforcement. Rebar cannot be plkaced on the bottom of a concrete element, and so rebar chairs help to raise the reinforcement off the bottom of formwork, the ground, or a prepared sub-base/base.
A rebar chair provides additional concrete cover constructability measures to ensure rebar/reinforcement is placed at the correct depth of construction for a concrete element.
Without rebar chairs, there could be concerns with allowing the reinforcement to be placed at the right elevation.
For instance, concrete reinforcement without adequate concrete cover is at greater risk of corrosion. For this reason, rebar chairs are used to elevate reinforcement off the surface of a concrete element and position it properly. This is generally the case where there is no vertical rebar to facilitate the proper installation height of subsequent layers of concrete reinforcement.
Photo Above: Concrete reinforcement placed on rebar chairs made to elevate the level of rebar off of the ground.
Tying Rebar
Tying rebar is a difficult and arduous task, and requires attention to detail and a strong ability to analyze project drawings and reinforcement shop drawings. The necessary placement of concrete reinforcement is typically a dictation of a structural engineer. For instance, for any given concrete element, a concrete cover of 50mm (2”) might be provided.
This would have to be achieved for an element like a SOG(slab on grade) concrete construction element.
So, to achieve this concrete cover, a rebar chair is used to elevate the reinforcement to achieve not only the concrete cover, but also the design requirements of the concrete slab.
Multiple Layers of Rebar
Some concrete slabs might have two or more layers of rebar. Concrete chairs again work to support the bottom layer of the rebar of a concrete slab, and the vertical rebar can be used to help support subsequent layers for thicker concrete slabs, like suspended concrete slabs or transfer slabs.
Concrete cover is an integral part of concrete reinforcement design, and so rebar chairs play a critical role in the overall structural integrity of any concrete element.
They help to ensure that rebar is at the right location overall when placing and finishing concrete. Placement of concrete using a pump, truck, or even by hand, can often dislodge rebar from its original tied position.
So in that case, rebar chairs are a more sturdy way of supporting the rebar where it needs to be to ensure the design specifications for a given concrete item or element are met. Such uses of concrete rebar chairs could be for a concrete driveway, concrete slab, grade beam, or other elements.
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Deluxe Concrete Services provides professional Calgary concrete services throughout Calgary and the surrounding areas. Their team takes on commercial Calgary concrete services and residential concrete jobs including: concrete patio construction, concrete pathways, concrete stairs, concrete foundations, concrete stamping and more.
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