Steel is one of the fundamental materials used in the construction industry. It is made using an alloy or combination of metallic iron with carbon (non-metal) added to improve its strength and toughness. It is then molded into bars commonly known as rebar, which also exist in the form of wires and wire meshes. These meshes and wires are used in different ways to hold steel together, especially in the creation of reinforced concrete during construction projects. Together with concrete, reinforced steel, bricks, and other materials create the building blocks or skeletons of any building structure.
To make the final work stronger, the rebar is patterned. The bars are meant to absorb the tensile, shear, and compressive stresses in concrete. When left unreinforced, plain concrete can barely withstand these forces, hence resulting in a weak building. The steel together with the concrete have a better chance of withstanding these forces. With this in mind, below is a brief overview of how steel is reinforced on a construction site.
1. Making Concrete
As much as we are reinforcing steel, some construction sites like kicking off the process by making concrete or at least having the needed supplies ready. Steelwork, however, comes first in most construction jobs. All the same, the concrete is made by mixing sand or other aggregates like ballast or gravel with cement. If you intend to make your concrete a bit stronger, increase the ratio of the cement in relation to the amount of sand you are using. An air entrainment additive is sometimes added to the mixture. The additive is meant to prevent cracking during cold weather by introducing microscopic air bubbles to the concrete. The addition of this additive should be as per the manufacturer’s instructions.
The concrete will lose water with time and will shrink, becoming even weaker. Using shrinkage reducing admixture to the concrete prevents shrinking and curling after the water loss. It is also advisable to add some corrosion inhibiting additives to the concrete to protect the reinforcement steel from corrosion, especially in structures handling marine water as it is known to corrode steel as well.
2. Steel Framework/Reinforcing the Concrete
Concrete and steel reinforce one another. This is basically because a structure can be made purely from steel or concrete, but the two are known to work better together. This is why some construction sites start with creating the framework from steel.
3. Check the Local State Building Codes
Every state has some building codes that contractors need to adhere to. When placing the reinforcement steel, it is important to take time and look at these codes. They will define the size and placement standards of the rebars, as well as how it should be done. As explained at www.reozone.com.au, different construction sites will need different types of construction-grade steel and accessories. These may include formwork, reinforcement bar rebars, concrete reinforcing mesh, expansion joints, and so forth.
The building codes cover the required standards for most of these things, and you will find them at the branch of the local government responsible for city planning. This is also why it is important to work with a reputed supplier of steel construction material where they are regulated, know the requirements, and strive to comply with the set standards. They can guide you on the amount and type of reinforcement steel to acquire. However, some of the main concerns when reinforcing steel include:
- The spacing between the individual rebars
- The grade of steel used
- The dimensions in terms of length and thickness of bars
- How much steel is needed?
4. Cutting the Rebars
After you have purchased the rebars, you will have to do some measurements of the construction site or where you intend to pour the concrete. With the length and width of the area where you intend to pour the concrete, you will cut the steel bars two inches less than these measurements. This is especially crucial to control cracks in nonstructural slabs, especially in areas more prone to temperature fluctuations. This means that when you are laying the bars on the site, they will be one inch away from the edges from each direction. It’s good to use a grinder fitted with a metal cutting blade to increase the precision of the cuts you will be making.
5. Tying the Rebars
As mentioned, the strength of the concrete can be increased when you pattern the steel bars. This is why the bars are tied together before the concrete is poured on them. Therefore, after you have measured the bars and cut them to the required lengths. Lay them down perpendicularly to each other to create a grid. Make sure to integrate the spacing specified in the building codes of your local state. At the point where two bars overlap each other, slip a piece of tie wire under them and then pull them over the bars.
Using pliers, twist the two ends of the wire tightly so the bars are tightly held together. This ensures the grid and the spacing is maintained even when pouring the concrete on them.
6. Have the Rebars Supported in the Area of Construction
When placing the steel bars, you need to make sure they are not at the bottom of the slab. To support the steel grid, rebar grid chairs can be used. They raise the bars to around two feet from the ground so the bars are not lying on the ground. This will make sure the concrete is adequately reinforced.
7. Pour the Concrete into the Steel Grid
The final step is usually to pour the concrete on the site. The concrete needs to be poured slowly so it uniformly spreads out. Make sure the rebar grid isn’t tampered with during the process. After that, even out the top and let the slab, row, or column dry. This could take a few days, in which the steel/concrete combination is allowed to dry at its own pace.
Steel reinforcement makes sure your concrete is strong enough to withstand any force it is subjected to. Concrete also reinforces steel in construction projects.