Guide to Use Steel Rebar

a. Planning and Design 

The process of using steel rebar begins with thorough planning and design. Structural engineers create detailed drawings that indicate the size, spacing, bending shapes, and placement of rebar within each element of the structure. These drawings are usually supported by a bar bending schedule (BBS), which guides the cutting and bending of steel rods into specific shapes such as hooks, stirrups, and ties. For instance, a typical slab might require 10mm TMT bars placed 150 mm apart in both directions. 

Without a proper plan, the structure might end up under-reinforced (weak) or over-reinforced (uneconomical).

b. Cutting and Bending 

Once the design is finalized, the next step is cutting and bending the steel bars according to the BBS. This is done using mechanical rebar cutters and benders or hydraulic machines for more precision on large-scale projects. Bending is performed to achieve the necessary anchorage and reinforcement shapes as specified in the structural drawings. During this process, it’s important to observe safety protocols, such as using gloves and eye protection, as steel bars can be sharp and dangerous to handle. 

Example: Bends in footings or hooks at the ends of bars provide anchorage and better grip within the concrete.

c. Tying and Placement 

After preparation, the tying and assembling stage begins. Here, the shaped rebars are tied together at intersections using 16-gauge binding wire to form reinforcement grids or cages. The ties must be secure to hold the bars in position during concreting. To ensure the steel bars do not rest directly on the formwork, spacers or bar chairs are used. These help maintain the required concrete cover, which is vital to protect the steel from moisture and corrosion. For example, in a column cage, vertical bars are tied to horizontal stirrups at regular intervals to form a robust frame. 

Example: In a slab, rebars are placed in two layers (bottom and top), tied with cover blocks at regular intervals to keep them lifted off the ground.

d. Concrete Pouring 

With the rebar securely in place, the next step is concrete pouring. Concrete must be poured gently and compacted using mechanical vibrators to ensure it fully surrounds the rebar without leaving air gaps. It’s important that the rebar does not move during this process. Workers should avoid stepping directly on the reinforcement and instead use walking planks or supports placed across the formwork. 

Finally, after pouring, the concrete must be cured properly—usually for a period of 7 to 14 days—to allow it to gain strength. Any exposed ends of rebar should be protected with anti-corrosion coatings or temporarily covered if they are to be used for future connections. Regular checks should also be made to ensure the steel remains embedded and protected from environmental exposure.