When envisioning a sturdy concrete structure-an illustrious bridge, a magnum-opus building. But far underneath the solid slab is a reinforcement system that keeps concrete strong and lasting. One very important yet often overlooked member of that reinforcement system is the rebar chairs.
While rebar chairs are little, insignificant beings, they perform valiant services in ensuring the durability and integrity of reinforced concrete. Come! Let us see why, indeed, these simple supports are the unsung heroes of construction.
What are rebar chairs?
To begin with, rebar chairs are small supports for holding steel reinforcement bars (rebars) in the desired position prior to and during the concrete pouring.
The goal is simple yet paramount: keep the rebar properly spaced and elevated so it becomes fully encased in the concrete once it cures.
The Idea Behind the Support
Before rebar chairs, the rebar establishes direct contact with either soil or formwork. While it may seem trivial, it is a serious problem for corrosion of steel, as concrete protects steel by covering it with the specific depth of concrete called “concrete cover.”
Types of Rebar Chairs
There are different rebar chairs for different construction necessities.
Plastic Chairs: These are light, corrosion-proof chairs that are usually suitable for residential or light commercial work.
Metal Chairs: These are much more durable; hence, they’re usually for heavy and industrial construction.
Concrete Chairs: These are very solid and also integrate within the pour, usually when there is a need for very high compressive strength.
Each of these has its own merits, so the deciding factors would usually be the weight to be borne, ecology, and finances.
Easy to Disregard, Difficult to Replace
Rebar chairs are often inexpensive and small in size; therefore the importance of rebar chairs is easy to disregard. But simply ignoring or misplacing the chairs will cause a big issue before you know it with. For example:
Rebar when irregularly placed will create a loss of structural integrity.
An inadequate concrete cover will create rust and cracking.
A poor support structure will cause the rebar to sag during the concrete pour causing the rebar to move out of place.
Where and When They Are Used
Rebar chairs can be utilized in concrete projects of all kinds including slabs, walls, columns, and foundations. Each chair is placed in a grid pattern below the rebar mesh or bars to create a consistent installation.
The installation of rebar chairs is easy and requires very little effort, but some degree of forethought is necessary.
The spacing of rebar chairs will still depend on the weight of the rebar, and how far the concrete will span. Some construction teams are using hundreds, if not thousands, of rebar chairs, to maintain even spacing and to keep everything stable.
A Cost-Effective Solution
Rebar chairs are not just effective; they’re also cost-effective! In comparison to all the other products used to support rebar, rebar chairs are a drawer purchase. They are low cost, easy and quick to install, are a small piece of the overall project cost, and can significantly affect the final strength of concrete. When you consider the potential for long-term damage from improperly support rebar, including cracked concrete, corrosion, and structural failure of the concrete, rebar chairs are a necessity rather than just a nice addition.
Improving Construction Quality
On to quality; I want to call out how rebar chairs also improve construction practice. They help ensure the rebar is installed properly per the engineering specifications, which helps facilitate quality control on the jobsite. The use of rebar chairs increases speed of placing rebar, as they provide consistency in spacing without a lot of adjusting.
In summary, rebar chairs help to provide accuracy and professionalism to a concrete project, regardless of scale.
Final Thoughts
Rebar chairs may seem insignificant, but their role in reinforced concrete construction is critical to producing resilient concrete. By holding the steel bars in place, concrete provides strength, safety, and longevity. This strength, safety, and longevity is not just physical; it helps provide peace of mind. Rebar chairs do their job quietly beneath the surface.
