Synthetic Fibers Concrete: What, why, how, types & 4 tips
Melacoll 2022-07-11 10:18

1. What are synthetic fiber reinforced concrete?

Stronger and more durable than ever! Synthetic Fiber is a synthetic material. Synthetic fibers concrete provides the required strength and a solid foundation for the building.

Synthetic Fibers are admixtures of concrete. It helps reduce plastic shrinkage cracking and increase surface durability. So Construction Companies should encourage to use of Synthetic Fiber reinforced concrete. This is for better quality and to ensure greater toughness construction.

2. Why use Synthetic Fibers?

In recent years, synthetic fibers have become more important as reinforcing material. It can solve corrosion problems at an affordable price. Markets have a wide range of fiber choices for reinforcing concrete available today. Contractors and homeowners began to realize its many benefits. And synthetic fibre reinforced concrete has been growing in the construction industry. Concrete communities pay more attention to reducing construction time and labor costs. Synthetic fiber can improve flexural strength, elasticity, and other mechanical properties. The result is improving the performance of concrete structures. There are some benefits of synthetic fiber concrete.


  • 1. Controls and mitigates plastic shrinkage cracking
    2. Reduce Segregation and bleed- water
    3. Provides three-dimensional reinforcement against micro-cracking
    4. Increases surface durability
    5. Easy to add to the concrete mixture
    6. No Dampness and Leakage
    7. Improved impact resistance of floors to point loads
    8. Increased Production speeds
    9. Increased site safety & efficiency

3. How does synthetic fibers do to concrete?

Concrete is a brittle, compressible material. but it is less effective under tension. Reinforcement is to absorb these tensile forces. So inevitable crack in all high-strength concrete does not weaken the structure. After reinforcement, now fibre-reinforced concrete appears. It includes polymeric, synthetic, and steel or glass fibers.

3.1. Synthetic fiber provides better water retention.

The reason for this is that these fibers can hold some water and hence slow down the evaporation process. Synthetic fibers can also detect certain limited tensile stresses, especially at an early age. So, we need to do something to check.

For example, when using synthetic fibers concrete, you need to know:

1. reinforcement requirements;

2. fittings requirements;

3. desired and achievable strengths;

4. historical data of materials used;

5. proper placement of the material;

6. Check the strength to ensure design specifications

3.2 Synthetic fibers hold the aggregate.

Synthetic fibers hold the aggregate(concrete materials). It can prevent the coarse aggregate from separating due to vibration/gravity. To provide better bonding to the matrix. This ensures a homogeneous mixture of concrete and fibers. Allowing water to pass to the surface, and reducing cracking in the concrete.

3.3 Synthetic fiber provides tensile strength.

The structural element has a very weak tensile force compared to compression. Concrete is easy to bend. So you need reinforcement to withstand the tensile force.

Synthetic fiber impacts on plastic and hardened concrete vary based on the concrete materials. Mix proportions, fiber type and length, and fiber quantity added is also important.

4. What types of synthetic fibers are used in concrete?


The main synthetic fiber in the US is rayon, PP, polyester, acrylic, and nylon. Synthetic fibers have different lengths, thicknesses, and shapes. Synthetic fibers offer similar advantages when used as secondary reinforcement in concrete.

4.1 PP synthetic fiber reinforced concrete


Which fiber is best for concrete?

Polypropylene fiber reinforced concrete is also known as polypropylene or PP. It does not absorb water and does not affect concrete water demand. It is a synthetic fiber, processed from propylene, and used in a variety of applications. PP fibre-reinforced concrete is hard, stable, and heat resistant. They are anti-static, non-magnetic, and non-conductive. The use of PP fibre-reinforced concrete is safe, environmentally friendly, and harmless.

different_types_of_synthetic_fibres_with_picturer (1)

Polypropylene fibers affect the physical and mechanical properties of concrete such as

flexural and tensile strength;
resistance to impact;
water absorption;
This property contacts with sustainability and ecological and economic characteristics.

Polypropylene Fiber is hydrophobic so it does not absorb water. So it does not affect concrete mixing water.

4.1.1. Why Polypropylene added to concrete?

Polypropylene fibers are one of the most common fibers used in engineering. Polypropylene fibers have certain properties that make them an ideal additive. You can achieve specific benefits when added to concrete. For example, Limiting the size of the crack. PP fiber-reinforced concrete can limit the width of cracks due to plastic shrinkage.
It is a plastic material with the lowest specific gravity. you need less material to produce the finished product. It can be installed immediately after bonding with concrete, saving construction time. You need less labor because fewer steps during construction work.

The fibers are easy to mix. they can normally be taken in pre-measured bags to be added at a rate of one bag per cubic meter of concrete. The manufacturer may recommend which fiber length to choose for this application. The fibers don't have much of an effect on workability. But they tend to slow the rate of bleeding, which can delay when the sheet can be removed.

PP fiber can also improve residual strength. Polypropylene fibers improve the surface of the ground.
This influences increases the possibility of use in shallow foundation, soft-soil embankments, and other high-strain earthworks.

4.1.2. Two Types of Polypropylene Fiber:

Polypropylene fibers include microfibers and macro fibers. This classification based on their length and the function in the concrete. They vary in length, but concrete's functionality is more important.

1 Macro synthetic fibers concrete


Macro fibers refer to as structural fibers and are intended to carry loads. And used to replace traditional reinforcement in certain non-structural applications. It can cut or eliminate early and late cracking. It can also provide resistance to plastic shrinkage. And it will also give concrete strength, and toughness. and to provide limited structural capabilities when properly designed.

Macro synthetic fibers have been shown to work with a wide range of concrete strengths. When exposed to fire, macro fibers soften as the temperature rises. It will melt at temperatures between 150 and 160 degrees Celsius. They don't suffer from the stain and spalling that might occur when steel is corroded. They are nominal reinforcement in hostile conditions, such as marine and coastal structures.

They've also applied to tram and light train systems because they're non-conducting.

2 Micro synthetic fibers  concrete

Microfiber is used to cut initial cracks. Micro Fibers are generally classified by length. But the diameter and the aspect ratio are taken into account. Although the microfiber offers resistance to the formation of plastic shrinkage cracks. It cannot resist cracks due to dry shrinkage, structural loads, or other forms of stress.

4.2 Polyester synthetic fiber concrete

Polyester is a synthetic fiber. Polyester fiber reinforced concrete (PFRC) has been evaluated for cement concrete pavement material. Polyester fibers increase concrete compressive, tensile strength, impact, and wear resistance. The fibers provide support to the concrete in all directions by being evenly distributed in the matrix. It also prevents the problem of corrosion. Like polypropylene, polyester fiber is hydrophobic. But, they tend to decompose in the alkaline environment of cement concrete.

4.3 Nylon synthetic fibers concrete

Nylon is the first fully synthetic fiber and the strongest synthetic fiber. Like polyester yarn, and nylon the threads are in the form of monofilaments.

What mainly distinguishes them from polypropylene and polyester fibers? Hydrophilic properties.

Nylon is particularly effective in providing impact resistance and toughness.  It can maintain and increase the load-carrying capacity of the concrete after the first crack. Nylon Fibers are manufactured with 100% pure synthetic fibre. It supplied as filaments for secondary concrete reinforcement.

5. 4 Tips on using Synthetic Fibers reinforced Concrete

Concrete is a versatile construction material. That is utilized in a variety of construction applications all over the world. Synthetic fibers are most in cast-in-place concrete, shotcrete and precast products.

synthetic fibers concrete application

5.1 Mixing synthetic fibers concrete

To generate high-quality fresh concrete, it's critical to combine the elements properly. Concrete needs appropriate workability and performance in both the fresh and hardened states. So well-mixed concrete is necessary. If the concrete is not thoroughly mixed, it will segregate and bleed. Careful mixing, the right equipment, and appropriate transportation are all necessary.

Fibers can be added with coarse and fine aggregate batch factory at the factory or at the truck mixer on the site. Synthetic fibers do not affect the chemical hydration of cement. They work with all concrete mixes and admixtures. And the mixing ratio of concrete does not change. These bags will collapse immediately materialize and distribute the content. Successful concrete mixing and transportation necessitates the careful regulation of many variables. You're ready to go on to the next vital phase, known as placement.
You've picked the right mixing and carrying equipment and handled the important factors. You are ready to go on to the next vital phase, known as placement.

5.2 Placing synthetic fibers concrete

Concrete placement is a crucial activity because it impacts success and long-term durability. All technical and climatic parameters must be treated with extreme caution.

Synthetic, steel and mixed fiber reinforced concrete need traditional tools. Like, concrete chutes, buckets, conveyors, and pumps.
Synthetic fibers blend into the cement paste. they do not interfere with structural reinforcement systems. and they have irregular shapes. For example, those used for curved driveways or some products prefabricated products. If the mixture is too strong to locate, don't add more water. It has the potential to deteriorate concrete that has hardened.

5.3 Finishing synthetic fibers concrete

How do you finish concrete with synthetic fibers?

Finishing is level, smooth, and compact for a perfect concrete surface. Finishing concrete that will be visible, such as roads, highways, or patios.

Synthetic fibers are compatible with all concrete surface treatments and patterned embossing. Concrete finishing is to make a smooth, long-lasting surface out of concrete. Timing is vital while completing concrete. and you must pay strict attention to the concrete's state. Improper finishing processes might result in fragile, damaged, and ugly slabs.

5.4 Cautions

Concrete contractors may face a variety of challenges when working on their projects. Sometimes it's due to technical concerns. such as improper concrete curing or an unsuitable material mix.

Concrete issues, for example, discolorations, shrinkage, and scaling. Routine inspections are important. Concrete contractors can help with this. you have a dependable concrete contractor on your side. It’s much easier to work on many concrete repairs. If you're having trouble with one of these problems. If you would like professional help, call a concrete contractor.

6. Putting the right Fiber for the right purpose in concrete

In engineering design, there are varieties of reinforcement. And they're rather exclusive from every other:
Primary reinforcement additionally called structural steel, is designed to hold loads. Secondary reinforcement(synthetic fiber concrete), typically cited as “temperature and shrinkage steel,”. It can reduce drying shrinkage and thermal enlargement and contraction. Many of the building industry should be in charge of current environmental and sustainability challenges.

Aggregate and cement businesses are being monitored by environmental protection agencies. They limit their demands for natural resources for climate change problems.


Posted by Melacoll

Hi, there, I have been engaged in the cellulose ether industry for 11 years.

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