The mixture of cement, sand, gravel and water, otherwise known as concrete, is leveraged for a wide array of construction projects. While the material has plenty of characteristics that make it ideal for applications like foundations, sub-grade walls, footings and more, it is also weak in tension and susceptible to cracking in response to shrinking or creeping under sustained loads. Therefore, it often requires the use of rebar for reinforcement.
Steel, the material used to create reinforcing bars (or rebar), features significantly greater tensile strength than concrete. When used to reinforce concrete, steel rebar lends more stiffness and ductility. Rebar expands and contracts at the same rate as concrete under temperature fluctuations, so it’s the ideal pairing for reinforcement purposes.
As rebar installation supports better performance of concrete under conditions of lateral and horizontal tension, torsion and compression, it is a vital component for ensuring durability, versatility and safety with load-bearing structures. Rebar is designed and installed by experts to create the appropriate shape, size and pattern to maximize bonding with the concrete and optimize performance.
Let’s take a closer look at what role rebar installation plays in concrete reinforcement and construction.
Rebar Installation for Primary & Secondary Reinforcement
With concrete structures fortified by reinforcing steel, the function of rebar can be categorized in two ways: primary reinforcement and secondary reinforcement.
- Primary reinforcement is the function of rebar in helping to carry the structural and environmental loads placed on a structure in order to prevent collapse.
- Secondary reinforcement, sometimes referred to as distribution or thermal reinforcement, is the function of rebar in maximizing durability and resisting the impacts of cracking, shrinking and other stress factors, like temperature changes.
In other words, consider primary reinforcement as the rebar that holds the structure up, and secondary reinforcement as the rebar that holds the structure together.
Rebar can also serve to provide resistance to concentrated loads in certain areas, spreading the load impact across a wider space, as well as to ensure that other steel bars stay in the correct position to handle their assigned loads.
Considerations for Proper Rebar Installation
In order for rebar to achieve its intended aims with regard to concrete reinforcement, it is necessary for the installation team to ensure several conditions for placement, positioning and other criteria:
- The rebar must be constructed from the applicable grade and type of steel for the job. Rebar is offered in various grades and thicknesses, and engineers choose these specifications based on the needs of the concrete installation.
- The rebar must feature the appropriate size, shape and length. The engineered design should conform to specific requirements and standards.
- The rebar must be applied in proper quantities. There are engineering calculations made to determine the proper amount of rebar needed to sufficiently reinforce a concrete structure.
- The rebar must be placed and spaced according to proper specifications. Rebar is laid in a grid pattern, and spacing is critical to the overall strength of the concrete. It’s also important to have adequate clearance between the reinforcing bars in order to ensure the concrete’s ability to completely surround the rebar.
- The rebar must be tied and spliced together correctly. It’s rare to have full-length, continuous bars that fit perfectly in a reinforced concrete structure, so splicing is usually necessary. Proper splicing and tying of the rebar is essential to the integrity of the concrete structure.
- The rebar must be clean and effectively maintained. Sometimes excessive rust can be a problem, but for the most part, issues like oil, dirt and loose mortar are most damaging to the reinforcing bar. These elements inhibit the adhesiveness of the steel to the concrete.
- The rebar must receive an adequate cover of concrete in all directions. Completely covering the rebar in all areas of exposed surface is critical to preventing corrosion of the steel against factors like moisture, atmospheric conditions and reactive soils.
Important Rebar Safety Information
It’s true that rebar is a common appearance at many construction sites, particularly those involving concrete. But working with and managing exposed rebar can be a difficult and dangerous effort. To prevent the hazards associated with installing rebar to reinforce concrete, it’s fundamental to heed rebar safety standards.
First, understand that any protruding rebar presents an opportunity for impalement or other worker injuries, which means proper navigation and use of rebar end coverings, or caps, are crucial. Some particularly hazardous conditions on the job include:
- When the concrete formwork pins are exposed at low levels
- When the concrete footing rebar is protruding into walking spaces
- When the rebar is extending out from the concrete foundation
- When rebar scraps are left unattended and lying around on site
Given the serious risk of injury or even death that these hazards pose, it’s fundamental to the safety of all workers that necessary precautions and practices are followed. These include efforts such as:
- Employing only properly trained and experienced rebar installation professionals who can properly recognize hazards.
- Wearing personal protective equipment, including gloves and eye protection, as well as tucking pants and shoestrings to prevent catching on the reinforcing material.
- Covering all exposed rebar with the proper protective caps, and whenever caps are not available, bending the rebar over correctly to safeguard against injury.
- Consistently picking up and storing scrap rebar, and keeping a safe distance when rebar is in the process of being hoisted in mats or cages.
- Immediately flushing any cuts with water and peroxide to mitigate the impacts of rust in the body, then covering and consulting a physician.
Rebar Installation Review
Ultimately, there are fundamental benefits to reinforcing concrete with rebar, particularly in civil construction applications. The steel design helps minimize concrete’s susceptibility to cracking and breaking, affording greater strength to the overall structure as well as absorbing and distributing the structure’s tension.
Rebar installation can also be a complex and dangerous job, which is why it’s vital to partner with an experienced construction team that thoroughly understands this process and can manage the rebar and concrete effort seamlessly.