Top Rebar Spacer Options for Durable Concrete Construction

In the world of construction, the strength and durability of a structure are heavily reliant on the quality of its foundation. One key component that plays an indispensable role in building a solid base is the humble rebar spacer. Ensuring the correct positioning and protection of steel reinforcement within concrete, rebar spacers are the unsung heroes that uphold the integrity of countless structures around us.

Key Takeaways

Rebar spacers play an important role in maintaining the correct alignment of rebars, providing a protective layer and facilitating concrete cover.
Various types of rebar spacers are available to suit different construction projects. Selection depends on factors such as structural weight and surface exposure.
Proper installation is essential for improved handling, connection methods vary depending on project requirements.

Understanding Spacers

Spacers for rebar, while seemingly simple and unassuming, play a fundamental role in maintaining the correct alignment of rebars in concrete structures before the pouring of concrete. They are the guardians of steel reinforcement, establishing and preserving a designated concrete cover over the reinforcement bars. This protective layer safeguards the reinforcement steel from corrosion, contributing significantly to the longevity of concrete structures.

The advantages of using rebar spacers, including concrete spacers, extend beyond this. By preserving the appropriate cover for the reinforcement bars and ensuring the reinforcement remains securely in position, they enhance the stability and support of the reinforcement bars. This is of utmost importance, as it significantly enhances the structure’s strength, durability, and safety.

The function of Spacers for Rebar

Spacers for rebar work to uphold the exact placement of steel reinforcement in concrete construction. They contribute to the improvement of concrete structure strength by:

Offering support to the reinforcing steel
Facilitating the attainment of the required concrete cover
Preserving the appropriate spacing of reinforcement bars
Ensuring sufficient bonding area
Safeguarding against potential corrosion

This enables the application of theoretical design specifications and the realization of robust structures.

What endows these spacers with anti-corrosive properties? A unique feature of rebar spacers is their zinc plating, which enhances their resistance to corrosion. Their conductivity, non-ferrous nature, and strength contribute to safeguarding concrete structures against corrosion, thereby promoting longevity and durability.

The concrete cover provided by rebar spacers typically ranges between 10 and 100 mm, which is crucial for protecting steel reinforcement bars and ensuring the structural integrity of the construction.

Types of Spacers for Rebar

There’s no universal solution in the construction industry. Depending on the specific needs of a project, different types of rebar spacers can be employed. These include single-dimension spacers, multi-dimension spacers, and plastic rebar spacers.

One popular type of rebar spacer is the wheel spacer. These spacers play a vital role in rebar reinforcement, ensuring proper spacing and positioning of the reinforcing steel. They serve as centralizers for reinforcement cages and help maintain the required concrete cover over the rebar.

Another type is the rebar chair, which serves as a spacer and provides support and upholds the proper positioning of reinforcing bars within concrete. The placement of rebar chairs at consistent intervals guarantees that the rebar is at the accurate height, shape and spacing as specified in the construction plans.

And then there are snap rebar chairs which offer convenient spacing and support for rebar, incorporating a snap function for secure product placement and easy movement. While these spacers share a common purpose, their functional variances are determined by their distinct features and shapes.

Choosing the Right Spacer Material

Choosing the appropriate spacer material can significantly influence the construction process. This decision is influenced by factors such as structural weight, potential rebar disturbance, and concrete surface exposure. For instance, concrete spacers are versatile and can be applied to a wide range of structures. However, differences in properties may potentially undermine the integrity near the spacer.

On the other hand, steel spacers, while robust, may result in visible rust spots on the poured concrete surface due to non-structural steel within the cover zone, rendering them unsuitable for exposed and visible surfaces. While plastic spacers may be a convenient option, they may not be suitable in scenarios involving the support of exceptionally heavy cages or in areas with a high likelihood of rebar being subjected to weight. In such cases, a concrete spacer can be an ideal solution.

Concrete Spacers

Concrete spacers, in particular, offer the following benefits:

Improved protection against corrosion by facilitating the necessary concrete cover for steel reinforcement
Serve as a protective barrier between the reinforcement and the surrounding environment, effectively preventing moisture and corrosive elements from reaching the steel
Ensure the durability and strength of the concrete structure
Maintain the correct spacing and alignment of the reinforcement bars, preventing any movement or shifting during the concrete pouring process

Solid rebar spacers establish a reliable link between the rebar and the concrete, particularly in vertical placements or when the rebar cage is lifted or exposed to vibration. They also aid in preventing bleeding and segregation in deep sections of concrete structures.

Plastic Spacers

Plastic rebar spacers offer a different set of advantages and disadvantages. On the plus side, plastic spacers provide advantages such as:

Ease of use
Cost-effectiveness
Fast processing
Maintaining proper reinforcement cover
Being lightweight for easier handling and transport

But they are not without their drawbacks. The use of plastic rebar spacers may lead to:

the potential weakening of structures
the inferior strength compared to steel and concrete spacers
the possibility of adversely affecting the concrete, acting as weak points in reinforced structures

Thus, it’s essential to consider the specific requirements of a project when deciding on the spacer material.

Popular Spacers for Rebar Products

Some spacers for rebar products are more widely used than others. Among the most commonly recognized are wheel spacers, rebar chairs, and snap rebar chairs. These products offer improved handling and transportation due to their lightweight plastic construction, making them suitable for a variety of construction projects, including building structures, ports, wharves, subway tunnels, civil defense engineering, railways, and expressways.

Rebar chairs, in particular, play a crucial role in construction projects by elevating the rebars to the desired height, ensuring correct positioning within the concrete. Snap rebar chairs, on the other hand, are recognized for their snap-on design and wide base, which ensures easy installation and reliable support.

Wheel Spacers

Wheel spacers are a popular choice due to their quick and easy installation process. They widen the distance between wheels, leading to improved handling and increased track width. The installation process involves attaching the spacers to the wheel hub and then mounting the wheels onto the spacers.

They maintain consistent spacing for rebar by interlocking the wheel members together to securely hold the reinforcement steel bars in place. This ensures the correct positioning during concrete casting and prevents any unwanted movement.

The standard dimensions of wheel spacers commonly utilized in reinforcing concrete range from 6mm to 50mm, accommodating diverse project requirements.

Rebar Chairs

Rebar chairs, on the other hand, offer versatility and sturdiness due to their construction from robust materials such as high-density plastic or non-corrosive metals. These materials offer essential support for maintaining the proper positioning of the rebar during construction, thereby improving the structural integrity of the concrete and minimizing the risk of potential cracking.

Depending on the specific needs of a project, different designs of rebar chairs can be employed. The common type elevates the rebar off of the ground and is typically utilized in foundation footings, concrete slabs, and other flatwork.

There are also reinforcement chairs or rebar spacers which are commonly employed in raft construction.

Snap Rebar Chairs

Snap rebar chairs offer a unique blend of convenience and functionality. They are utilized in concrete construction to provide support and positioning for reinforcing steel bars (rebar) within a concrete structure. What sets them apart is their snap-on design and wide base, which ensures easy installation and reliable support.

But while they are convenient and an easy way to use, they may not be suitable for all scenarios. A potential drawback is the possibility of corrosion over time, as the steel reinforcement can be exposed to moisture and other corrosive elements. Nonetheless, their durability, ability to withstand the weight of the rebar without collapsing or deforming, and their ease of installation and removal make them a practical choice for many construction projects.

Proper Installation and Connection of Spacers

Correct installation and connection of rebar spacers are vital in upholding the accurate concrete cover and the integrity of the structure. Failing to utilize appropriate rebar spacers can lead to corrosion and premature deterioration of the structure. It’s also important to consider the minimal height or the concrete cover dimension that the spacer will provide for the rebar when ordering rebar spacers.

The installation process involves:

Preparing the fabrication of the vertical bars, lateral ties, and necessary wires
Ensuring the presence of safety scaffolding
Positioning and spacing the rebar chairs or bricks accurately
Ensuring the levelness of the rebar
Placing rebars at uniform intervals
Avoiding placing rebar directly on fresh concrete
Strictly adhering to engineering specifications for rebar placement.

Spacer Height and Positioning

Correct spacer height and positioning are key to achieving the correct concrete cover for the rebar. Accurate concrete spacer and height in rebar installation ensure the appropriate concrete cover for the steel rebar, safeguarding it from corrosion and contributing to the structural integrity of the concrete structure.

The firmness of the subgrade also has a direct impact on the positioning of rebar spacers. In cases where the subgrade is not firm, it is crucial to utilize spacers with adequate contact areas, such as concrete cubes or cylindrical blocks, to ensure proper support and positioning of the rebar during concrete construction.

When adjusting cover thicknesses, it’s recommended that for #6 bars and larger, the minimum concrete cover should be 2 inches. For #5 bars or smaller, the minimum concrete cover should be 1½ inches.

Connection Methods

Different connection methods for spacers and rebar can be employed based on the specific requirements of a project. These include using tie wire and hooks to connect rebar spacers, offering advantages such as improved handling and transportation. Continuous spacers offer a consistent and prolonged method of rebar spacing, ensuring adequate space between bars.

Alternatively, spacers with holes can be used to facilitate the connection with the rebar by enabling the rebar to pass through their central holes. This configuration effectively secures the spacers to the rebar, preventing any potential movement or displacement and thus ensuring the proper positioning and position of the reinforcement during the concrete pouring process.

Applications of Rebar Spacers in Different Construction Projects

The use of rebar spacers is not confined to just one type of construction project. They find applications in various projects, such as precast concrete, tunnels and underground structures, and vertical formwork, to ensure proper reinforcement and durability.

In precast concrete construction, rebar spacers provide support for horizontal surfaces, fasten systems for tubbing construction, and elevate the surface of the rebar matrix above the ground. This elevation facilitates proper concrete flow underneath, ensuring the reinforcement’s correct positioning and durability within the precast element.

In the construction of tunnels and underground structures, rebar spacers maintain the correct spacing and alignment of reinforcement bars and columns, contributing to the overall structural integrity and long-term durability of the structure.

In vertical formwork construction, rebar spacers offer support and ensure proper spacing between horizontal reinforcement bars, maintaining the desired form of the structure.

Precast Concrete

Rebar spacers play a significant role in precast concrete applications, ensuring proper internal coverage and uniform spacing for the reinforcement bars. This ensures the structural strength and longevity of the concrete, safeguarding the reinforcement from potential damage during transportation and while in use.

However, precast concrete applications often present unique challenges that require specialized spacers, compared to poured concrete. These challenges revolve around the need for precise rebar cutting and bending to achieve accurate placement and alignment conditions, as well as ensuring sufficient concrete cover for durability and structural integrity.

Remedial measures include the use of automated machinery for precise rebar shaping and the meticulous selection and installation of spacers to uphold the necessary concrete cover.

Tunnels and Underground Structures

Rebar spacers are key in the construction of tunnels and underground structures, contributing to the structural stability and durability of these projects. They address challenges such as restricted inspection access, the risk of shear failure, and the management of groundwater infiltration.

However, these structures are particularly susceptible to corrosion due to their exposure to moisture and other corrosive elements. Therefore, it’s recommended to use materials such as galvanized rebar and corrosion-resistant fibers like carbon fibers (CFPR) or aramid fibers (AFRP) for rebar spacers in these applications.

Vertical Formwork

Vertical formwork projects come with their own unique set of challenges that demand robust and reliable spacers. Rebar spacers play a crucial role in form, providing support, and ensuring proper spacing for the reinforcement bars. They maintain the correct position of the rebar, preventing sagging or shifting during concrete pouring, thereby preserving the structural integrity of the formwork.

The criteria for rebar spacers in vertical formwork encompass ensuring their structural integrity, thorough installation of reinforcement, and appropriate spacing following the dimensions of the reinforcing bar. Hence, the most suitable type of rebar spacer for use in vertical formwork is a tip or round cap spacer, specifically designed for vertical installation and offers a bottom or top concrete cover for the rebar.

Summary

In conclusion, rebar spacers play a pivotal role in concrete construction projects. Their proper selection, installation, and positioning ensure the correct concrete cover for the rebar, ultimately safeguarding the reinforcement steel from corrosion and contributing to the structural integrity of the concrete structure. Whether it’s precast concrete, tunnels and underground structures, or vertical formwork, choosing the right rebar spacer material and the right product itself can significantly impact the strength, durability, and longevity of the construction project.

Certified MTP offers a full line of Rebar Chairs, Concrete Rebar Chairs With Base, Concrete Rebar Chairs Without Base, Rebar Mesh Chair Supports, Tilt-Up Rebar Chairs, Rebar Safety Caps, Rebar Spacer Wheels, and Ground Penetrating Radar (GPR) for Concrete, Concrete Test Hammers, Concrete Corrosion Testing for Concrete, and Concrete Crack Monitoring. The rebar detection and location equipment is available for fast and free shipping.

Frequently Asked Questions

What is the purpose of a rebar spacer?

The purpose of a rebar spacer is to secure the reinforcing steel in reinforced concrete structures, ensuring the required thickness of the concrete cover and keeping the rebars in place during pour, and after the concrete pour.

What is the function of spacers?

Spacers help to hold the medicine in place, making it easier for the user to breathe it in while using an inhaler. Contact your doctor, asthma care team, or pharmacy for further information about inhalers, spacers, or mouthpieces.

What are steel spacers used for?

Steel spacers are used to ensure the spacing between the reinforcement layers in floor, ceiling, and wall installations of mats and steel bar reinforcements. They are essential for maintaining proper structural integrity.

What is a rebar cap?

A rebar cap is a plastic safety device designed to fit all sizes of rebar and comply with safety codes like OSHA and ANSI. It is placed on the end of the rebar to prevent potential impalement injuries for workers.

What are the attributes and potential drawbacks of using plastic spacers?

Plastic spacers offer ease of use, cost-effectiveness, and lighter weight for easier handling, but they may lead to weakening of structures, have inferior strength compared to steel and concrete spacers, and potentially affect concrete quality. It’s important to consider these drawbacks when using plastic concrete spacers.