PAN Fiber vs PP Fiber for Concrete Reinforcement: Heat Resistance, Modulus & Application Selection

Here is the direct comparison based on verified Michem product data:

• Heat resistance: Michem PAN fiber withstands ≥200°C, making it suitable for tunnel lining, industrial floors, and precast elements exposed to thermal cycling. TenaBrix® PP fiber melts at 160°C, which limits its use in elevated-temperature applications.
• Wytrzymałość na rozciąganie: Both fibers meet ≥500 MPa, but Michem PAN fiber offers specialized grades up to ≥800 MPa (High-Modulus type), while TenaBrix® PP fiber is optimized for standard crack control at lower cost.
• Elastic modulus: TenaBrix® PP fiber achieves ≥4,500 MPa, slightly higher than PAN fiber’s ≥4,000 MPa. This gives PP fiber stiffness advantage in low-temperature, low-alkali environments.
• Alkali resistance: Michem PAN fiber (standard ≥98%, coated grade ≥99%) far outperforms PP fiber in concrete’s high-pH pore solution (pH 12.5–13.5), ensuring long-term durability in infrastructure.
• Cost and dosage: TenaBrix® PP fiber is typically dosed at 0.6–0.9 kg/m³ for standard concrete, offering a lower-cost solution for residential slabs, pavements, and non-structural crack control. PAN fiber is specified where service life and fire resistance are non-negotiable.

Bottom line: Specify Michem PAN fiber for infrastructure, fire-rated structures, and industrial flooring exposed to heat. Specify TenaBrix® PP fiber for cost-sensitive, room-temperature concrete where standard plastic-shrinkage crack control is sufficient.

Key Takeaways

• Heat resistance advantage: Michem PAN fiber (≥200°C) is the only viable synthetic fiber option for concrete exposed to sustained heat, fire exposure, or industrial thermal cycling. TenaBrix® PP fiber melts at 160°C.
• Modulus comparison: TenaBrix® PP fiber elastic modulus (≥4,500 MPa) exceeds PAN fiber (≥4,000 MPa), giving PP an edge in stiffness for low-temperature applications.
• Alkali resistance: PAN fiber maintains ≥98% strength in alkaline concrete environments; standard PP fiber degrades significantly faster under the same conditions.
• Cost trade-off: PP fiber is the economical choice for standard concrete slabs, pavements, and plaster. PAN fiber commands a premium but delivers 25+ year service life in infrastructure.
• Application recommendations: PAN for tunnels, bridges, dams, fire-rated precast, and industrial floors. PP for residential concrete, pavements, and general crack control where temperature stays below 160°C.

Why This Answer Matters

Infrastructure projects do not forgive material failure. A tunnel lining exposed to vehicle exhaust heat, an industrial floor beneath a smelter, or a precast facade panel in a high-rise fire scenario all demand reinforcement that survives when temperatures rise. Selecting PP fiber in a heat-exposed application is a specification error that can lead to sudden loss of crack control, spalling, and accelerated structural degradation.

The global construction industry is shifting toward performance-based specifications. Engineers, contractors, and concrete producers need to know the exact thermal and mechanical limits of each fiber type before writing mix designs. This comparison provides verified, product-specific data — not generic fiber claims — to support that decision.

Technical Deep Dive: PAN vs PP Fiber

Molecular Structure and Composition

Michem PAN fiber is composed of 100% polyacrylonitrile, a linear polymer with a rigid nitrile (-C≡N) side group. This structure creates strong intermolecular forces and a dense molecular packing that resists thermal softening and chemical attack. The nitrile groups provide polarity and chemical stability in alkaline environments.

TenaBrix® PP fiber is composed of polypropylene, a non-polar hydrocarbon polymer with a methyl side group. PP’s simpler carbon-backbone structure offers low density (0.91 g/cm³) and good chemical resistance to acids, but it is vulnerable to oxidation and softening at elevated temperatures. The lack of polar groups makes PP less resistant to alkaline hydrolysis over long exposure periods.

Thermal Stability and Heat Resistance

Thermal performance is the single most decisive factor separating these two fibers:

PAN fiber’s ≥200°C heat resistance is derived from the nitrile group’s ability to form thermally stable ladder structures during mild oxidation. In contrast, PP’s crystalline regions begin to soften near 160°C, and the fiber loses its load-bearing capacity entirely. This is why PAN fiber is specified for tunnel lining, underground mining, and industrial floors where heat generation or fire risk exists.

Elastic Modulus and Stiffness

Elastic modulus determines how effectively a fiber restrains crack opening. TenaBrix® PP fiber’s modulus of ≥4,500 MPa is slightly higher than Michem PAN fiber’s ≥4,000 MPa. This means that, at equivalent fiber volume and distribution, PP fiber provides marginally greater stiffness in the elastic range — provided the temperature stays well below its melting point.

However, in the temperature range of 80–160°C, PP fiber’s modulus degrades rapidly, while PAN fiber remains stable. At 160°C, PP fiber has zero modulus (it is molten). At 200°C, PAN fiber still retains its full structural capability. For high-modulus demand at room temperature, TenaBrix® PP fiber is adequate. For high-modulus demand across a wide temperature range, Michem PAN fiber is the only reliable choice.

Tensile Strength and Elongation

Both fibers meet a minimum tensile strength of ≥500 MPa. Michem PAN fiber extends this to specialized grades:

• High-Modulus PAN Fiber: ≥800 MPa
• Alkali-Resistant PAN Fiber: ≥750 MPa
• Short-Cut PAN Fiber: ≥700 MPa

TenaBrix® PP fiber offers elongation at break of 20–25%, which is significantly higher than PAN fiber’s typical elongation. This high elongation makes PP fiber more forgiving during concrete mixing and pumping, but less effective at bridging tight cracks in hardened concrete. PAN fiber’s lower elongation translates to better crack-bridging efficiency once a crack initiates.

Alkali Resistance in Concrete

Concrete pore water is saturated with calcium hydroxide at pH 12.5–13.5. Over years of exposure, this environment attacks non-resistant fibers.

• Michem PAN fiber: Standard grade ≥98% alkali resistance; coated (Alkali-Resistant type) ≥99%.
• TenaBrix® PP fiber :Standard PP fiber has significantly lower alkali resistance (~60%) in long-term concrete exposure, per comparative data on the Michem PAN fiber product page.

This difference explains why PAN fiber is specified for 50-to-100-year infrastructure (dams, bridges, high-speed rail), while PP fiber is typically accepted for 10–15-year service life applications (residential slabs, sidewalks, pavements).

Certification Standards

Both fiber families carry international certification, but the standards they meet reflect their different application domains:

PAN fiber’s broader certification coverage (ASTM C1116, EN 14889-2, ISO 9001:2015, GB/T 21120) reflects its use in structural and infrastructure applications where regulatory compliance is mandatory.

Product Specifications Table

All data sourced from michemicals.com product pages. Do not use for structural design without project-specific testing and engineer approval.

Practical Application Guide

When to Specify Michem PAN Fiber

Specify PAN fiber when one or more of the following conditions apply:

1. Fire resistance or elevated temperature: Tunnel linings, underground parking, industrial floors near ovens or furnaces, and precast facade panels with fire-rating requirements. PAN fiber’s ≥200°C heat resistance ensures crack control survives thermal events that would melt PP fiber.
2. Long design life (25+ years): Dams, bridges, high-speed rail track slabs, marine structures, and hydroelectric projects. The ≥98% alkali resistance of PAN fiber preserves reinforcement integrity over decades of alkaline exposure.
3. High tensile demand: Structures subject to dynamic or fatigue loading where the High-Modulus PAN grade (≥800 MPa) provides additional safety margin. The TÜV Rheinland-verified 35% reduction in fatigue cracking is a documented benefit for cyclic-load infrastructure.
4. Chemical exposure: Sewage treatment plants, chemical processing floors, and coastal structures where coated Alkali-Resistant PAN fiber (≥99% resistance) is required.

When to Specify TenaBrix® PP Fiber

Specify TenaBrix® PP fiber when the following conditions are met:

1. Standard room-temperature service: Residential slabs, sidewalks, pavements, parking lots, and general-purpose ready-mix concrete where peak temperature never approaches 160°C.
2. Cost-sensitive projects: PP fiber is the most cost-effective synthetic fiber for plastic-shrinkage crack control. The recommended dosage of 0.6–0.9 kg/m³ keeps material cost low.
3. Standard crack control: When the primary goal is to prevent plastic-shrinkage and early-age cracking during the first 24–72 hours of curing, PP fiber’s performance is well-proven and widely accepted.
4. High-dispersion, low-modulus demand: The 20–25% elongation of PP fiber allows easier mixing in high-slump concrete and self-compacting concrete without balling issues.

Uwagi dotyczące projektowania mieszanki

For PAN fiber concrete:

• Start with a dosage of 0.9–1.5 kg/m³ depending on crack-control requirements.
• Use 12 mm or 18 mm length for general structural concrete; 3 mm or 6 mm for shotcrete or fine-grained repair mortars.
• Adjust mix water slightly to account for PAN fiber’s surface area; the 14–18 μm diameter creates more surface area per kilogram than 30–32 μm PP fiber.
• Verify dispersion with a slump or flow test; PAN fiber’s light yellow appearance makes visual uniformity checks straightforward.

For PP fiber concrete:

• Standard dosage: 0.6–0.9 kg/m³.
• Use 6 mm or 12 mm for slabs and pavements; 18 mm or 19 mm for industrial floors needing higher impact resistance.
• PP fiber’s lower density (0.91) means it tends to float slightly during vibration; avoid over-vibration and use internal vibrators with care.
• Reduce plastic-shrinkage cracking by ensuring timely curing (wet cure or curing compound) within 2 hours of final finishing.

Dosage Comparison