Reinforcement of concrete screed: why is it done and what materials are used

Improving the strength and longevity of your flooring requires reinforcing a concrete screed. The longevity of your concrete surfaces is ensured by proper reinforcement, whether you’re building a new project or remodeling an existing one. It aids in preventing cracks and other damage that might develop over time as a result of temperature fluctuations or heavy loads.

Knowing why reinforcement is required can have a significant impact on the final product’s quality. Steel bars and mesh are examples of reinforcement materials that help the load be distributed more evenly throughout the concrete. This increases the screed’s longevity while also enhancing its structural integrity.

A concrete screed can be reinforced with a variety of materials, each having advantages of its own. Synthetic fibers, wire mesh, and steel rebar are typical choices. The particular requirements of your project, such as the anticipated load and the surrounding conditions, will determine which material is best.

We’ll go into more detail about the benefits of reinforcing concrete screeds and the various materials that can be used for this important project in the sections that follow. By the time it’s all through, you’ll know exactly how to reinforce your concrete screed and give your floors a strong, long-lasting foundation.

Reason for Reinforcement	Materials Used
Increases strength and durability	Steel rebar
Prevents cracking	Wire mesh
Improves load distribution	Fiberglass mesh
Reduces shrinkage	Plastic fibers
Enhances stability	Steel fibers

The need for reinforcement

In essence, adding reinforcement to a concrete screed makes it stronger against vibration and horizontal loads. There are multiple methods to improve the fill. To select a particular approach, you must be aware of the desired outcome. For what reason is reinforced concrete used?

The following tasks are carried out by reinforcement that is placed correctly:

• increases linear strength;
• minimizes the risk of cracks during drying;
• prevents and limits the process of building subsidence;
• reduces the formation of cracks or their increase as a result of physical impact;
• significantly extends the service life of the building.

Reinforcement materials

A reinforced concrete screed greatly improves the building’s overall strength characteristics. The process of adding a second internal layer or incorporating unique fillers into concrete mortar is known as reinforcement.

For this, a variety of tools and techniques can be employed:

• rod steel reinforcement;
• composite rods;
• metal mesh;
• polymer mesh;
• fiberglass mesh;
• fiberglass.

Kindly take note! Even though there is a long list of options, the reinforcement process is not considered cost-effective. Although concrete reinforcement can be completed for the least amount of money, it is still a costly procedure. Therefore, you must ascertain whether reinforcement is necessary in this specific instance before adding more screed to the screed.

When reinforcement is necessary

Let’s first categorize concrete works according to where they are executed and how they function. Therefore, concrete mortar is used to pour floor slabs, screeds of all kinds, and foundations.

• rough on the ground and base;
• leveling;
• floating;
• multilayer;
• bonded.

Reinforcing the fill is required if:

• thermal insulation material is laid;
• when planning increased physical loads on the floor surface;
• when installing a floating screed;
• if the fill thickness is more than 50 mm;
• when installing a floor heating system;

Note: Any concrete fill is reinforced for safety in seismically active zones.

After discussing the circumstances in which a reinforced concrete screed is required, we will go into a detailed explanation of the reinforcing procedures and materials.

Reinforcement options

Concrete screed can be reinforced by adding filler to the solution or by installing various mesh types. Regarding strength indicators, the efficiency of each method varies. Naturally, reinforcement for a floating screed is different from that for a leveling fill. Additionally, any operation should be carried out using one of the suggested materials to avoid wasting any resources.

Rod reinforcement

Today’s market offers two materials that are representative of this kind of reinforcement:

1. classic steel rod grade A500C or A400,
2. composite reinforcement: basalt-plastic, carbon fiber, fiberglass.

Rods of any kind are arranged in a mesh and secured in a nodal connection by welding, or knitting construction wire in the case of steel reinforcement grade A400. The diameter of the rod is chosen based on the anticipated loads. Every rod in a single horizontal line of a tied or welded mesh needs to be the same size.

Steel reinforcement

The most robust screed reinforcement among the alternatives is achievable with a steel rod. Car boxes, warehouses, and industrial workshops all have concrete screeds installed that are strengthened with metal rods.

• Steel rods of a periodic profile with a diameter of 8 to 12 mm are used for binding into a mesh.
• If necessary, larger rod sizes are used, but this happens quite rarely.
• The cell size in a mesh of this type ranges from 50 * 50 mm to 150 * 150 mm. The lattice can be tied or welded directly at the construction site or prepared in industrial conditions and delivered to the site.

Take note: It is preferable to avoid welding the mesh together if there will be significant dynamics of horizontal weight loads on the floor. The screed’s integrity will be preserved while a wide bending amplitude is provided by the connected structure.

• The cell size and the rod diameter are calculated at the stage of building design. These indicators are affected by the probable amount of static and dynamic loads on the concrete screed.

Composite reinforcement

Is a wire-tied mesh that is directly analogous to steel reinforcement. The use of composite reinforcement in dry and semi-dry screed devices has grown significantly. Use in building, however, is only permitted with the designers’ consent.

Take note! Currently, during the design phase, every computation is done using a standard steel rod. The rod diameter and cell size are altered when recalculating for composite reinforcement.

• Low weight facilitates transportation and reduces the weight of the floors;
• Transportation in coils and measurement of the required rod length is possible;
• No risk of corrosion, has a long shelf life.

Ready meshes

One option for strengthening a concrete platform is to use prefabricated mesh. There are a lot more options available in this situation. There are specific load requirements for each type of mesh that can be used. The material of the rod used to make the web serves as the determining indicator.

Metal

Wire with a diameter of 2.5 to 6 mm is used to make the mesh. From 60 to 200 mm in cell size. The greater the load that the screed can bear, the stronger the mesh and the smaller the cell size. Rolls of wire mesh with a maximum string diameter of 3 mm are available from manufacturers. Larger diameters are available in specific-sized sheets.

Benefits of this kind of reinforcement include:

• high tensile strength;
• excellent binding property;
• immune to temperature changes;
• long service life.

There is very little chance of cracks when using such a mesh because the wire stretches well. Simultaneously, the surface’s ability to support loads increases noticeably.

Plastic

Polypropylene mesh can successfully replace metal mesh when reinforcing screeds up to 80 mm thick. The material is lightweight, pliable, and elastic. It stretches nicely without deforming, which is a huge benefit.

When the building shrinks unevenly, the mesh will flex to hold the screed in place rather than tearing it like a metal one would. However, due to its low tensile strength, this type of material is only suitable for use in low-load rooms in private construction projects or apartment screeds.

Manufacturers sell mesh rolled up. The material is perfectly stored and cuts easily with regular scissors. It also resists corrosion and rotting.

• elasticity;
• chemical inertness;
• does not interfere with the passage of radio frequencies;
• low weight;
• easy to install.

Fiberglass

An aluminoborosilicate fiber mesh can be used for reinforcement of the concrete preparation process.

• Such nets are produced with a small cell with a cross-section size of up to 6 mm. When buying, you should pay attention to the presence of impregnation.
• Some of the impregnating compounds significantly increase the resistance of the web to an alkaline environment, which is of great importance when reinforcing a cement-based screed.
• A mesh without impregnation will last in such a screed for no more than 5 years, which is ineffective. Otherwise, in terms of performance characteristics, it is very close to a plastic material.

Installation of reinforcement

Except for fiber, which is covered below, all of the materials on the above list are installed in accordance with the same guidelines. The bottom third of the screed is where any mesh is placed.

In this instance, the mesh web ought to be inside the screed rather than touching the base’s surface. The material is usually laid using stand blocks (shown below), which hold the material at a specific height. Often, builders refer to them as "chairs."

When using metal structures, it’s especially crucial to keep the reinforcement at a height. The waterproofing film, which is typically laid before pouring concrete, can be ripped by metal. Pouring a reinforced screed is exactly the same as installing a regular one in all other ways.

Crucial! When placing an order for concrete with rod reinforcement, you should deduct the volume that the reinforcement will take up from the total volume of the fill.

The installation of mesh reinforcement differs greatly from the use of fiber. On the packaging provided by the manufacturer, there are instructions for mixing and a suggested quantity. Fiber is evenly distributed throughout the entire volume of concrete by mixing it into the concrete solution.

Reinforcing the screed with fiber

Fiber is a concrete reinforcement ingredient. Small fibers: directly mixed into the concrete’s composition, measuring between 6 and 20 mm.

Fibers come from a variety of materials.

• polymers;
• fiberglass;
• metal;
• basalt fiber.

Various types of screeds require different fiber compositions.

• For light screeds that do not require resistance to significant physical loads, glass or polymer-propylene fiber is suitable.
• If the surface will experience significant mechanical impact, a metal material should be used.
• External, street screeds exposed to chemically active substances or atmospheric precipitation, road dirt, are arranged using basalt fiber.

Fiber-reinforced concrete will keep the screed from settling and prevent it from cracking during drying. It is preferable to use a different kind of reinforcement if it is required to withstand severe mechanical impact, bending, or stretching.

This article’s video will demonstrate how to properly mix and pour a fiber-based screed.

Be aware that fiber, in addition to the primary reinforcement of a rod or mesh, will greatly enhance the performance of any screed.

Fiber in foam blocks

Additionally, fiber is utilized in the production of foam concrete blocks.

In the following areas, reinforced foam concrete outperforms traditional blocks by a significant margin:

• tensile strength;
• resistance to cracking;
• impact strength and increased resistance to technical fatigue;
• resistance to temperature changes;
• water absorption.

Strength indicators in concrete are doubled when reinforced with a mesh or rod. The same indicators will increase three times when fiber is used. Fiber-reinforced foam concrete greatly outperforms conventional in terms of both technical and physical attributes.

A concrete screed needs to be reinforced in order to be strong and long-lasting. You can greatly increase the screed’s resistance to stress and crack prevention by adding materials like steel bars, wire mesh, or synthetic fibers.

Different benefits are provided by different reinforcement materials. Strong support is provided by steel bars and wire mesh, which makes them perfect for high-load areas. For smaller projects, synthetic fibers are an affordable option that help distribute stress and lower the chance of cracks.

In the end, the particular requirements of your project will determine which reinforcement material is best. Making educated choices will help you ensure a sturdy and long-lasting concrete screed by helping you understand why reinforcement is required and what materials are available.

To increase a concrete screed’s strength and durability, stop cracks from forming, and guarantee a stable, long-lasting surface, reinforcement is necessary. The procedure entails putting materials into the concrete, such as wire mesh, steel rebar, or synthetic fibers. The screed is more resistant to normal wear and tear thanks to these materials, which also help distribute loads more evenly and withstand different stresses. Your concrete screed’s lifespan can be greatly increased, and you can preserve a strong base for driveways, floors, and other surfaces by reinforcing it.

Video on the topic

A simple way to lift welded mesh or reinforcement in a screed from the base.