Fiber mesh concrete, or fiber reinforced concrete, is an alternative to steel-reinforced concrete. What are the advantages of fiber mesh concrete, and how does it work?
What Does Fiber Mesh Do For Concrete?
Fiber mesh concrete incorporates fibers into the concrete mix design at the job site. These fibers can vary in shape, size, and material, depending on the purpose they serve in that project.
Does Fibre Mesh Add Strength to Concrete?
Concrete is incredibly strong in compression, but its tensile strength rates at one-tenth of that value. Adding macrofibres to the concrete mix design improves flexural strength. When done correctly, the tensile strength could increase by quite a large margin, nearly matching that of the compressive strength in some cases.
What Types Of Fibres Are Used in Concrete?
Fibers in concrete are divided into two categories according to size: microfibers and macro fibers. Microfibres are tiny, up to 10mm in length, and don’t add strength to hardened concrete. Instead, these fibers minimize bleeding in fresh concrete, potentially eliminating hairline cracks associated with excessive bleeding. Microfibers are generally made of synthetic materials or polymers and are soft to the touch. Their texture is similar to that of synthetic hair, almost like doll’s hair.
Macrofibres are larger than microfibers, up to 50mm in length, and are made of metals or synthetic polymers. These are stiff, strong fibers with a ridged or stepped profile to better grip the hardened concrete. Macrofibres add tensile strength to cement-concrete mix designs – more on this in the next section.
Nowadays, synthetic fibers are just as strong as their metallic counterparts – even stronger, in some cases. The benefit of synthetic fibers often renders them preferable to the metallic version since they are sometimes cheaper to manufacture, and they are corrosion resistant.
Here’s how this works: macro fiber profile shape lends itself to concrete gripping to it. As mentioned above, these fibers have a ridged and often stepped profile. As the concrete hardens, it grips onto this profile, properly entrenching the fibers into the concrete’s crystalline structure. When a crack forms in the concrete, its spread is halted by these fibers. Here, the fiber effectively keeps the two sides of the crack together. Extensive research in this regard shows that fibers are highly effective in this regard.
In floor slabs, fiber reinforced concrete often requires fewer joints than its unreinforced or steel mesh reinforced counterparts. Here, the fiber adds enough flexural strength to prevent shrinkage cracks. It also enables the concrete to bear a more significant point load, like the case in warehouse floors with heavy forklift traffic. In warehousing applications, the design engineer should avoid construction joints and any other form of joint since these become sites for localized surface damage. Here, the hard forklift wheels wear out the joints’ sides, causing the concrete to crumble and crack. These cracks spread, causing significant damage to the floor structure. Simultaneously, these damaged areas cause damage to the forklift wheels, which the building owner must replace. This situation creates an unnecessary expense for the warehouse management company.
Fibre Mesh Concrete Pros And Cons
Advantages of Fiber Reinforced Concrete
Disadvantages
Fibre Mesh Concrete vs Rebar
Is fiber mesh better than rebar?
The fibers are usually packaged in a water-soluble bag dropped into the back of a ready-mixed concrete truck while mixing is underway. This fresh concrete is poured and placed at the job site like any other, with little to no change in its workability and consistency. Generally, fiber concrete is easy to work with and makes for easy placement compared to steel-reinforced concrete. It also saves time and space on site since there won’t be piles of steel mesh stored on-site and no time-consuming set-up of this mesh.
That said, these fibers must be added to the back of the ready-mix truck slowly, allowing for proper dispersion, or polymer fibers should be used instead of steel to avoid clumping. Polymer fibers are not prone to clumping and generally disperse evenly through the entire batch of wet concrete.
Conversely, including rebar in a concrete structure is highly work-intensive and requires precise site practices. When placed correctly, rebar, or steel reinforcement, lends extensive flexural strength to the structure. However, when things go wrong, and placement is done incorrectly, steel reinforcement could weaken the structure since it then adds weight to the wrong part of the structure without increasing the tensile strength in the areas most needed.
Should I Put Fiber in My Concrete?
Fiber mesh concrete is easy to work with and, when used in floor slab applications, could easily replace traditional steel-reinforced concrete. It is also quicker and much easier to use at the job site. The key here is to use the correct fibers for each application. The mix design engineer must choose between micro-and macro fibers and between steel and synthetic fibers, each of which is suited to specific applications and performance parameters.
In this blog, we will compare the rebar with fiber mesh about which is suitable for reinforced concrete, when they should be used, different types and sizes, and how to install them.
Are you planning a wall, pavement, or bridge? Trying to figure out whether you need rebar or fibers in the concrete for your pavement? To decide which one to choose as your concrete reinforcement is necessary. We need to figure out several factors and the designs of them.
In this blog, we will compare the rebar with fiber mesh about which is suitable for reinforced concrete, when they should be used, different types and sizes, and how to install them. Finally, we hope you may make the best decision from our statement. By the way, we will also compare fiber with rebar and wire mesh and explore when and where to use it. Our purpose is to provide you with the information necessary to determine if you need concrete reinforcement for your project.
Fiber or Rebar?
There are always tricky questions as “Is steel fiber better than rebar as concrete reinforcement?” “Should I choose rebar over fiber mesh?” The truth is, you don’t choose hamburgers over cola! You choose the hamburger only when you are hungry. By the same logic, you choose fiber mesh as concrete reinforcement only when you need something to prevent the potential micro-cracks from your concrete. And when you need something stronger enough to limit the width of the cracks, rebar will be your other choice. Follow us in this blog and figure out the difference between fiber mesh and rebar reinforcement so you can make a better decision to reinforce your concrete slab.
When comparing the tiny fiber with the cumbersome steel rebar , also known as the reinforcing bar, the first thing popping in your mind must be: “How can the delicate fiber rifle with the bulky rebar?” Here is the point, they do different jobs. The fiber mesh concrete reinforcement strengthens the concrete slab while the steel rebar reinforces the extra load areas. In other words, fiber is for shrinkage cracking while the concrete cures. You may use fiber as reinforcement on pedestrian areas like a patio or sidewalk. But when your concrete supports heavy loads or large vehicles, it should be reinforced with the steel rebar to improve its tensile strength. Using fiber under this condition is a bold move.
Let’s discuss it case by case.
*Fiber Reinforced Concrete
1.What is Fiber Reinforced Concrete?
Simply put, Fiber Reinforced Concrete (FRC) is the concrete with cement, aggregates, sand as a concrete base mixed with fibers to perform its reinforcing function. Fibers suitable for reinforcement can be steel fiber, polypropylene fiber, macro-fiber, and glass fiber. As the concrete dries, it creates an internal mesh throughout the slab. It imparted a heightened level of impact resistance. It is always useful when constructing smaller sidewalks or patios.
2.Types of Fiber Reinforcement used in Concrete?
1. Carbon Fibers.
They are light, plastic, and have high tensile strength. It has high chemical resistance, great performance in corrosion resistance. Carbon fibers have a high-temperature tolerance.
2. Polyester Fibers.
Polyester fiber is a popular choice for warehouse and other industrial floors, pavements, and precast products. Polyester macro and microfibers are mixed with concrete to ensure structural integrity, toughness, and to protect against plastic shrinkage cracks.
3. Polypropylene Fiber.
Polypropylene, or PP, is a type of fiber used in concrete because it is resistant to drying shrinkage and plastic shrinkage. This fiber helps reduce water bleeding in concrete and reduces the concrete’s permeability. Polypropylene fiber is a synthetic white rugged material with good conducting properties and has great resistance against organic solvents, acids, and alkali.
Adding steel fiber to the concrete mix increases the concrete’s durability, resistance to cracking, resistance to bending, strength, and toughness.
Cellulose fibers are used in the textile industry as fiber reinforcement composites and chemical filters.
They perform well in building and designing ground-supported slabs. Because they do not suffer from the staining and spalling problems that may result from steel corrosion. As they are not conducting, they are present in the tram and light rail fields.
3.Pros and Cons of using the Fiber Reinforced Concrete?
Advantages
1.Fiber-reinforced concrete has more tensile strength and reduces cracking when compared to non-reinforced concrete
2.Fiber-reinforced concrete reduces crack growth and increases impact strength and leads to a greater strain capacity of the composite material.
3.Fiber-reinforced concrete improves resistance against freezing and thawing.
4.Reinforcing concrete with fiber increases fatigue strength
5.Macro-synthetic fibers are used to improve concrete’s durability.
6.Made from synthetic materials, these fibers are long and thick in size and may be used as a replacement for rebar or wire mesh reinforcement thus minimizing steel reinforcement requirements
7.Improve mix cohesion, improving pumpability over long distances
8.Increase resistance to plastic shrinkage during curing
9.Controls the crack widths tightly, thus improving durability.
10.Reduces segregation and bleed-water
Disadvantage
1.Heavy rain may expose the fiber.
2.Fiber is not evenly distributed in concrete and may lead to poor concrete quality.
3.Fiber reinforced concrete is more expensive, about 10% to 15% higher than non-reinforced concrete.
4.Deformation is the main drawback of fiber-reinforced concrete.
5.It is difficult to detect early and handle problems in time when placing because the fibers in the concrete make the concrete very rough.
6.The fiber concentration position is not controllable and it requires skills to make it evenly distributed. Sometimes the fibers may clump up, resulting in poor concrete quality.
7.The concrete becomes roughened due to the fed fiber, so it may require a higher water/cement ratio.
8.The process of mixing fibers into the cement matrix is more expensive and labor-intensive than the production of ordinary cement concrete.
4.Applications of Fiber Reinforced Concrete
The applications of fiber reinforced concrete depend on the different demands of the applicator and the different characteristics of the targeted constructions. Here are some of its applications-
Tunnel Dams
Lining Hydraulic
Slope Structure
Stabilization Elevated decks
Thin Shell Roads
Walls Bridges
Pipes Warehouse
Manholes Floors
Other application includes oil tanks, concrete repairing, water tanks, machine tool frames, lightning poles, etc.
*Rebar
1.What is rebar?
Reinforcing rebar has been supporting reinforced concrete panels for more than 150 years to improve the tensile strength of concrete. Rebar is made of hot-rolled steel of different specifications. Rebars are used to strengthen the concrete from the inside.
For ease of use, it is usually also placed into a steel mesh, or placed in parallel lines. The thicker the rebar and the more frequently it is placed, the stronger the finished product will be. Rebar is used to reducing concrete cracks due to tension forces. Concrete has great compressive strength, but may crack or break if not fully supported underneath or from within.
Steel rebar improves the ability of concrete to withstand forces applied horizontally or vertically. It distributes the force through the concrete, rather than allowing the concrete to penetrate and crack. Reinforced concrete is stronger and more stable than concrete without reinforcement. Rebar is often referred to as deformed steel because the ridges make it bond with concrete.
Of course not all concrete needs rebar. Concrete slabs used for pavement or driveways for cars, light trucks, or bicycles don’t need reinforcing rebar. If the concrete will need to support heavy machinery or heavy-duty vehicles, a bridge, or a swimming pool, a rebar is recommended.
2.Types of rebar
1.Carbon Steel Rebar concrete reinforcement
Hot-rolled carbon steel rebar, or ‘black bar, is the most preferred rebar. It is ridged, yet can be bent, and provides structural strength to concrete.
2.Galvanized Rebar concrete reinforcement
The steel is galvanized with zinc by cold or hot plating or electroplating for protection. It has better resistance to corrosion than carbon steel.
It is often used for road or bridge construction beside the sea where salt corrosion may be an issue.
3.Stainless Steel Rebar concrete reinforcement
Stainless steel rebar is better suited for seismic, impact, fire. It has the best corrosion resistance and is very, very strong.
4.Epoxy-Coated Rebar concrete reinforcement
It has been used in bridges and roadways subject to saltwater or deicing salts. Unfortunately, the epoxy coating is less durable than the galvanized coating and even a pinhole perforation can lead to corrosion. Epoxy-coated rebar has been banned in some jurisdictions and is under review in others.
5.Wire Mesh concrete reinforcement
Steel wire mesh is a common method for strengthening and casting concrete. The wire mesh forms a square grid pattern which is laid before the concrete is poured. Steel mesh is a grid of layers of two-dimensional mesh that runs along the length and width of the poured concrete, not height.
During the concreting process, workers will raise the laid wire mesh to run along the middle of the concrete height. As the concrete solidifies around the wire mesh, there will be a reinforcing material inside the concrete, which helps prevent cracking during temperature changes and when the concrete sets.
3.When should I use rebar reinforcement?
Applications of rebar lie as follows:
Slab
1.Stone slabs larger than 5 inches thick.
2.Slab that may support the perimeter or interior of a vertical building
3.Slab that spans weak or disturbed ground, or over drains or ditches.
4.Slabs that may support materials like heavy equipment, dump trucks, construction supplies, or liquid drums.
Small concrete slab
It depends on where you use it. If the ground is solid enough, a slab with only a table on it does not need rebar reinforcement, but if you put a staircase on this small slab connecting two floors, you are trying your luck. A small four-inch-thick cushion supporting a fireplace or hot tub should be reinforced. Remember that rebars help prevent cracking when the weight is distributed or when the plate is poorly supported.
Pavement
Pavements, especially driveways or trails often loaded with heavy machines or parades, should also be strengthened. Pavements will often have expansion cracks cut or placed, thus cracks appear. Sidewalks across the weak ground, tree roots, or drainage areas benefit from rebar reinforcement. Many walkways that cross lanes or are often crossed by heavy equipment or loads should also get reinforced by rebar.
Wire mesh
Wire mesh is a common method for strengthening and casting concrete. The wire mesh forms a square grid pattern which is laid before the concrete is poured. Steel mesh is a grid of layers of two-dimensional mesh that runs along the length and width of the poured concrete, not height. During the concreting process, workers will raise the laid wire mesh to run along the middle of the concrete height. As the concrete solidifies around the wire mesh, there will be a reinforcing material inside the concrete, which helps prevent cracking during temperature changes and when the concrete sets.
4.Advantages
1.Compatibility with Concrete.
2.Robustness of Steel Reinforcement.
3.Bent Property of Steel Reinforcement.
4.Recycling Property.
5.Easily Available.
6.Elastic.
5.Disadvantages
1.Easy to conduct chemical reaction with other materials
2.Melting tendency under high temperature
3.The cost is high. conclusion
*Comparing Fiber q & Rebar & Wire Mesh from the perspective of cost, durability, and time-consumption:
1.Cost
On the surface, fiber costs the most, followed by the steel mesh, rebar is the cheapest. Yet, given that the amount of fiber added is minimal, plus, the intermediate transportation and labor costs will be saved, fiber is still affordable. Plus the addition of fiber to the concrete is the most effective (Fibergo provides customized water-soluble packaging. You can throw it into the blender). The transportation and the operation process of rebar give you a lot of trouble. An extra process is also required for connecting the reinforcement. You need enough space to store the wire mesh.
2.Durability
Because of its strength, steel has always been on the gold standard. This is true for both vertical and horizontal applications. By contrast, the wire mesh is less robust, not least because each rod has shrunk in size.
In theory, fiber mesh is the most popular option for contractors today. Although most of the impact resistance offered by this fiber mesh can only work in a limited area, concrete with fiber reinforcement has no fear of cracking due to corrosion. Fiber is still the best choice in the long run.
3.Time consumption
Rebar is by far the slowest of the three. Connecting rods takes time to align and rearrange (via ties or welding). The wire mesh is faster as it needs to be rolled out, aligned to fit. Fiber mesh can be the fastest option, depending on the material added during the curing process. In any case, this method does not require any cutting, making it less of a workload.
*Conclusion
In summary, fiber reinforcement is the most appropriate choice for reinforced concrete for various industrial-scale projects. And more and more contractors accumulate their preference for fibers as their choice for concrete reinforcement. So if you’re building a pavement, wall, or any load-bearing structure, the fiber would be a solid reinforcement option.
At the same time, contractors will find fiber a more useful reinforcement because of its low addition, variety, and ease of operation. Taken together, if you’re planning to build your yard, driveway, or garage floor, then you should also take a closer look at the fiber mesh. The price of this option can be well managed on these scales, while still allowing you access to its enhanced tensile strength levels.