What Are Polyacrylonitrile (PAN) Fibers and How Do They Work?

pioneerfiber
Jul 18
3 min read

Updated: Nov 15

Information Tags

• Type: 4-minute read

• Audience: Construction professionals, engineers, architects, contractors

Introduction

Polyacrylonitrile fibers—commonly referred to as PAN fibers—are advanced synthetic microfibers known for their superior tensile strength, thermal resistance, and durability in concrete and asphalt reinforcement. Unlike polypropylene or steel fibers, polyacrylonitrile fibers offer a unique combination of fineness, stiffness, and chemical stability, making them ideal for demanding structural applications.

As concrete technology advances, more engineers and material scientists are turning to PAN fibers to solve persistent challenges such as early-age cracking, poor ductility, and reduced service life under aggressive conditions.

Close-up of white polyacrylonitrile (PAN) fibers used in concrete and asphalt to improve tensile strength and crack resistance.

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What Are Polyacrylonitrile Fibers?

Polyacrylonitrile fibers are synthetic micro monofilaments made from high-purity PAN polymer. They are characterized by:

Very fine diameter (~13μm): Nearly invisible to the eye but highly effective in dense matrix dispersion.
High tensile strength (600–900 MPa): Enables post-crack bridging and ductile failure behavior.
High elastic modulus (7–10 GPa): Ensures early-age stress absorption and crack width control.
Non-melting under 220°C: Suitable for fire-exposed zones and hot mix environments.
Chemical inertness: Stable in high pH, sulfates, chlorides, and hydrocarbons.
Excellent fiber-cement bonding: Achieves strong adhesion for efficient load transfer.

Large spool of polyacrylonitrile (PAN) fibers in industrial production, used for high-performance concrete and asphalt reinforcement.

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How Do Polyacrylonitrile Fibers Work in Concrete?

1. Crack Control at All Ages

PAN fibers intercept microcracks during both plastic (early) and hardened stages of concrete. Their high modulus allows them to absorb and redistribute tensile stress before cracks widen.

2. Post-Crack Ductility

When cracking does occur, PAN fibers bridge the gaps, maintaining tensile resistance and enhancing energy absorption—particularly important in seismic, tunnel, or precast applications.

3. Improved Shrinkage Resistance

By distributing shrinkage stresses across a dense fiber network, PAN fibers reduce internal strain and minimize drying shrinkage cracks.

4. Thermal and Chemical Resistance

PAN fibers maintain integrity in chemically aggressive or high-temperature environments, outperforming polypropylene which softens around 160°C.

Advantages Over Conventional Fibers

Property	PAN Fibers	Polypropylene Fibers	Steel Fibers
Diameter	~13μm	18–40μm	≥150μm
Melting Point	~220°C	~160°C	No melting (but corrodes)
Modulus of Elasticity	7–10 GPa	~3.5 GPa	~200 GPa (but rigid)
Bond with Cement	Excellent	Moderate	Poor without coating
Surface Aesthetics	No fiber protrusion	May appear on surface	Can rust or shadow
Chemical Durability	High	Medium	Poor in sulfates/chlorides

Applications of Polyacrylonitrile Fibers

PAN fibers are tailored for high-demand concrete and asphalt applications:

Tunnel linings and shotcrete for energy absorption and rebound reduction
Precast panels and facades requiring smooth surfaces and microcrack control
Bridge decks and industrial floors exposed to heavy loads and thermal cycles
Thin overlays and repair mortars for shrinkage resistance
Hot mix asphalt and composite road structures with improved tensile support

Aerial view of a wastewater treatment plant using PAN fiber-reinforced concrete for enhanced durability in aggressive chemical environments.

Conclusion: The Role of Polyacrylonitrile Fibers in Modern Concrete

Polyacrylonitrile fibers represent a significant advancement in the field of fiber-reinforced concrete. Their fine diameter, high strength, and chemical stability make them a powerful tool for enhancing concrete toughness, minimizing cracking, and extending service life—especially in aggressive or complex environments.

Whether used in large-scale infrastructure or precision architectural elements, PAN fibers offer engineers a high-performance reinforcement solution without compromise.

Explore PIONEER’s range of concrete reinforcement fibers and how they improve concrete properties. Visit our website: www.pioneerfibre.com

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