Details about Rebar Support and Chair Spacing
So you are involved in a construction project comprising of heavy steel rebar and you are wondering what different types of rebar support are available in the market and what could the best choice be for rebar chair for seamless spacing.
Reinforcement is placed in concrete at specific distance and orientation to provide sufficient area of steel at each section of the structural component. Therefore, the rebar will not be suitable, when the order of distance and orientation is not retained at site according to the design intent.
In large construction projects, 12 meter long dowels are provided in inclined positions and in multiple layers keeping distance of around 150 mm. Under such situations, Contractor should incur huge amount for the purpose of getting rebar supports and rebar chairs.
Collapsing of any of these supports may lead to destruction at the site. So, there should be proper rebar support in a construction project.
A rebar chair also known as rebar spacer stands for a rebar support device that tie the rebar in exact location and in required spacing before the concrete is poured. These supporting devices are treated as essential part of the permanent structure and implanted in the concrete.
Types of Rebar Support - The following types of rebar supports are commonly used:
1. Rebar Chair Support or Stools
2. Rebar Spacer Support
The word Rebar Chair is generally applied for support system towards reinforced concrete slabs, floors, sidewalks or driveways; they uplift the rebar off the ground by securing its position and arranging the necessary cover from the ground. If the slab contains multi-layers of rebar, these chairs should comprise of slots for two or three layers as per the structural design.
Rebar spacers stand for those types of rebar supports which are found in reinforced concrete walls, columns, piers or piles etc. They fix the vertical and horizontal rebar in exact location with the center to center clearance among various layers of rebar as well as arrange the necessary cover from the edge of the formwork.
Rebar Support Variations: The flat bottom chairs are also available to avoid the chair tips from suspending the vapor barrier and retaining a more secure surface.
Steel chairs with plastic tips cab also be used. They are cost-effective and can be utilized when small spots of erosions are found on the surface. Stainless steel chairs also exist, but they are little expensive as compared to traditional chairs, and when plastic can’t be provided into the concrete or when the weight is heavy for the plastic chairs.
Rebar Support Problems: Often, chairs will be overturned, when necessary cover is in excess of 2.5 inches, since the height to width ratio is insufficient, to facilitate the workers from walking over.
Besides, when they are too far away, the rebar will bend in the middle because of its weight, and extra chairs will be needed for some areas or the chairs can actually rupture owning to extreme weight. Some steel chairs having a plastic tip might untie the plastic protection all through the installation process, providing a feasible area on which corrosion can occur and the concrete surface will be damaged.