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Reinforced concrete is a widely used composite material made up of concrete and steel. In addition to steel, a few other concrete reinforcing products and accessories are added to the mix, so that it acts as a monolithic unit to hold up the entire structure. They contribute to the tensile strength of a structure and, hence, need to be durable and suitable for all types of projects.
The products/accessories required for reinforcing concrete are:
1. Dowel bars
A dowel bar is a short and smooth cylindrical steel bar used to facilitate the connection between two slabs. Generally, the bar is 18 inches long, and its diameter is within 1.25 to 1.5 inches. It is used in concrete pavements, slabs, columns, and staircases. It transfers the load to its adjacent slab and reduces the impact of loading on a single slab. Dowel bars reduce joint faulting by allowing the contraction and expansion of slabs.
2. Tie bars
Tie bars are connectors or deformed steel bars that interlock the aggregate together by maintaining contact between the faces of rigid slabs. They are usually placed across longitudinal joints and between an edge joint and a shoulder or curb. These bars are made using epoxy-coated steel and help inhibit differential settlement and transverse cracking.
Reinforcement bar or reinforcement steel, widely known as rebar, is a steel bar that is used in reinforced masonry and reinforced concrete structures to hold and strengthen the concrete in tension. They can be of different types such as mild steel, deformed steel bar, stainless steel rebar, etc. The type and grade of the rebar can be identified with the help of the identification code engraved on it.
4. Steel Mesh
A steel mesh can prevent a concrete slab from cracking and possible breakage. This reinforcing accessory is not as strong as rebar but can be used for smaller jobs. Although it is made of steel, it looks very similar to any finely-woven material. Apart from slabs, it is also used in columns, walls, and sidewalks.
5. Trench Mesh
As the name suggests, trench meshes are made for trenches (especially residential footing trenches), narrow spaces, and paths. It is also used in rock walls and brick walls. The trench mesh is manufactured in the form of long and narrow sheets. The longitudinal diameter of the mesh can go up to 16 mm.
6. Rebar ligatures
Rebar ligatures are popularly known as stirrups. They are mainly tied from top to bottom of reinforcing rods, collectively forming a cage or column structure. They enhance the overall compressive strength of the columns and beams and help in holding the main reinforcing bars together.
The commonly used ligatures are in the shape of a rectangle or square. They are also available in a triangle, pentagon, circle, hexagon, and other shapes. Their surface could either be plain or ribbed and are commonly made in diameters of 5.6 mm, 6 mm, and 10 mm.
7. Bar chairs
A chair bar is a four-legged arrangement made out of steel. It could be plain, epoxy-coated, galvanized, or plastic-tipped. The chair bars support the reinforcement bars at specific heights in a concrete slab by holding it in the correct position. It also ensures that there is a proper cover of concrete over the reinforcement.
They are used in the suspended slab, slab-on-ground having metal base or staircase.
8. Tie Wires and Bar Ties
Tie wires are extensively used to tie and fix reinforcing bars together. These wires are made up of ductile and durable steel, and are annealed, zinc-coated, PVC-coated, or galvanized for protection from the external environment.
Bar ties are tie wires with loops on both ends. They also help in securing the reinforcement rods during the placement of concrete. The eye hooks or loops at the ends of the bar tie make it easy to fix it by hand or an installation tool. It is also known as bag tie wire, double loop wire, or rebar tie wire. They, too, are galvanized, annealed, and coated with PVC.
9. Tie Twister or Puller
Tie twisters or tie pullers are tools that help secure the ties with the reinforcement bars. A neat, robust, and snug finish can be attained at a faster pace using these tools.
The different types of concrete reinforcing accessories are dowel bar, tie bar, rebar, steel mesh, trench mesh, rebar ligatures, bar chairs, tie wires and tie twisters.
Dowel bars serve as a load transferring device and tie bars are for maintaining interlocking of aggregates.