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High-Performance Concrete Reinforcing Fibers

Concrete reinforcement strategies often use specialized fibers to improve the durability and toughness of concrete. These fibers differ in shape, length, chemistry, and dosing requirements, and how they interact with the concrete matrix. Understanding these distinctions is essential for making an informed and effective choice to achieve the desired performance requirements.

At R-E-D Industrial Products, we specialize in supplying high-performance acrylic concrete reinforcing fibers that work seamlessly with modern concrete demands. Our products are specifically designed to address the unique challenges facing the concrete industry, and our engineered proprietary acrylic fibers enhance concrete durability and simplify the construction process. 

Read on to learn more about our acrylic fibers and their independently verified benefits.

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What are Concrete Reinforcing Fibers?

Concrete reinforcing fibers improve toughness and durability by controlling crack development throughout the concrete matrix. They come in various forms, including steel, synthetic polymers, glass, and recycled substances. In specific applications, some fibers can reduce the need for traditional steel reinforcement.

The Two Primary Functions of Concrete Fibers

They perform two primary jobs to enhance concrete performance. Firstly, they work to prolong the life of the concrete in its early, uncracked state. Added during mixing and dispersed throughout the matrix, they control initial cracking by intersecting microcracks and reducing their progression into macrocracks. This early crack control mechanism, often referred to when discussing concrete's "toughness," is crucial for improved durability.

Secondly, fibers significantly enhance the concrete's post-crack performance. Even if larger cracks develop, the fibers act as a three-dimensional reinforcement network, holding the concrete together and allowing it to remain functional longer. This capability is key to their role as effective secondary reinforcement, often replacing traditional methods like wire mesh in various applications.

Common Fiber Types and Their Uses

The selection of concrete reinforcing fibers often begins with their material composition. Steel fibers, for example, provide good thermal resistance and mechanical anchorage, making them well-suited for high-temperature applications or heavy industrial floors. Synthetic fiber options‌ typically offer strong corrosion resistance and improved freeze-thaw durability, which are advantageous for outdoor projects and areas exposed to chemicals.

Several other characteristics influence fiber performance and suitability. The physical shape of synthetic fibers is important; monofilament fibers are usually single, smooth strands, while fibrillated fibers have a net-like structure designed to open during mixing for enhanced mechanical grip. Fiber length, which can range from under an inch to over two inches, also affects how fibers bridge potential cracks.

Finally, two critical operational factors are dispersion and dosage. For fibers to be effective, they must spread out evenly within the concrete mix; poor dispersion leads to inconsistent performance and weak spots. Dosage rates, typically between 0.1% to 2% by volume, must be carefully chosen, as higher dosages can improve crack control but may also negatively impact the concrete's workability and finish if not managed correctly.

Engineering and Design Considerations

Engineers consider the following when designing fiber-reinforced concrete formulations:

• Crack width control: Helps prevent chemical infiltration and extended structural longevity.

• Fiber type characteristics: Micro-fibers under 0.3mm reduce early-stage cracking, while macro-fibers over 0.3mm enhance post-crack resilience.

• Application areas: Industrial floors, pavements, tunnel linings, precast components, and blast-resistance infrastructure. Effective macro fiber use in these areas can sometimes allow for optimized slab thickness, leading to project cost savings.

• Hybrid fiber systems: Combining two or more fiber types and sizes to achieve performance specifications.

• Testing methods: Fiber-concrete compatibility is validated through standardized testing protocols outlined in ICC-AC32, including flexural analysis and toughness evaluations.

R-E-D Industrial Products AC50 and AC60 Fibers vs. Competition

Our proprietary level 1 AC50 and level 2 AC60 acrylic fibers are engineered to create more durable and highly crack-resistant concrete. They provide effective secondary reinforcement and can eliminate plastic shrinkage cracking by up to 90%. We provide Environmental Product Declarations (EPDs) detailing the environmental performance of our fiber products.

Their material composition includes alkali resistance, insolubility in water, and the ability to form a strong chemical bond within the concrete paste. The non-protruding characteristic of these fibers ensures an easy concrete finishing process. All R-E-D Industrial Products fiber products meet the ASTM C-1116 Section 4.1.3 standard.

Here’s a breakdown of how our AC50 fibers compare to standard polypropylene mono fibers:

Feature	AC50	Polypropylene Mono (Plastic)
Fiber type	Acrylic (Precursor for Carbon)	Mono Polypropylene (Plastic)
Diameter	1.5 Denier	7-10 Denier
Length	1/4" – 3/4" (inches)	3/4" (inches)
Bag size	1/2 lb	1lb
Fiber Count (approx. per lb)	1/4" = 800 Million 3/4" = 260 Million	30 Million
PSCR (Plastic Shrinkage Crack Rate)	90%	70%
Bond	Ionic	None

Here’s how R-E-D Industrial Products AC60 fibers compare to standard poly fibrillated fibers:

Feature	AC60	Poly Fibrillated (Plastic)
Fiber type	Acrylic (Precursor for Carbon)	Fibrillated Polypropylene (Plastic)
Diameter	1.5 Denier	N/A (fibrillated structure)
Length	1/4" – 3/4" (inches)	3/4" – 1 1/2" (inches)
Bag size	2/3 lb	1.5 lb
Fiber Count (approx. per lb)	1/4" = 1.05 Billion 3/4" = 350 Million	1 Million
PSCR (Plastic Shrinkage Crack Rate)	94%	60%
Bond	Ionic	Mechanical
Finish	Very Smooth, No Hairy Finish	Can leave a “hairy” finish

Fiber Characteristics Impact on Performance:

PSCR (Plastic Shrinkage Crack Rate): This measures the fiber's effectiveness in reducing early-age cracking as the concrete sets. A higher percentage indicates significantly better crack control and a more durable initial surface. This early control also helps mitigate issues like slab curling that arise from differential shrinkage.

Diameter (Denier): Denier measures fiber fineness, with lower numbers indicating finer fibers. The denier specification affects fiber count per pound and dispersion characteristics within the concrete matrix.

Fiber Count: A higher fiber count means millions or billions of fibers per pound. This large quantity creates a dense three-dimensional reinforcement network within the concrete for enhanced overall toughness and durability.

Bond Type (Ionic vs. Mechanical): The ionic bond contained within creates a stronger chemical adhesion between the fiber and the concrete paste. This contrasts with a purely mechanical bond, leading to overall reinforcement effectiveness and contributing to sustained durability well beyond the initial curing phase.

Finish Quality: The smooth, no-hairy finish achievable with R-E-D Industrial Products acrylic fibers reduces the need for additional surface work and results in a more aesthetically pleasing and durable concrete surface.

Independent Testing of AC50 and AC60 Concrete Reinforced Fibers

AC50 fiber effectively controlled plastic shrinkage in the tested concrete. Its inclusion reduced the average crack widths by more than half compared to unreinforced concrete samples. This substantial reduction indicates a more intact and durable concrete surface during the critical early curing phase. This level of performance helps maintain the concrete's integrity from the outset.

The test results for AC60 fiber showed an even greater reduction in average crack widths. It achieved a nearly 80 percent decrease under the severe drying conditions imposed by the test. This effective crack mitigation under severe environmental simulations directly enhances the concrete's early-stage integrity. These independent findings confirm that both AC50 and AC60 fibers substantially limit early concrete cracking.

Choose R-E-D Industrial Products Acrylic Fibers for Optimal Concrete Performance

Careful selection of concrete reinforcing fibers is essential for controlling early-age cracking.

R-E-D Industrial Products's AC50 and AC60 acrylic fibers offer a proven alternative to traditional methods. Independent laboratory tests validate their significant impact on reducing plastic shrinkage cracking.

At R-E-D Industrial Products, we are committed to providing advanced concrete reinforcement solutions. Our acrylic fibers are engineered to meet demanding project requirements and contribute to durable, long-lasting structures. Click below for a quote and to learn more about how concrete reinforcing fibers can improve the toughness and durability in an endless number of applications.

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