Types of Micro Synthetic Fibers for Concrete

Suitable for architectural engineers, structural engineers, flooring contractors, precast component manufacturers, and technicians.

Micro synthetic fibers are widely used in modern concrete to control plastic shrinkage cracks, improve surface durability, and enhance early-age performance. However, not all micro synthetic fibers are the same—different materials and structures deliver different engineering outcomes.

This article provides a complete overview of the main types of micro synthetic fibers used in concrete reinforcement, their features, and where each type performs best.

Monofilament PP Fibers (Micro Polypropylene Fibers)

Micro monofilament polypropylene fibers are the most widely used type of micro synthetic fibers for concrete. They consist of single, smooth, and uniform strands with diameters typically between 18–40 microns.

Features

• Hydrophobic, non-corrosive polymer

• Excellent dispersion in concrete and mortar

• High tensile strength and chemical stability

• Minimal impact on workability when dosed correctly

• Effective at controlling plastic shrinkage and settlement cracking

  
  

Best Applications

• Industrial floors

• Residential slabs

• Pavements

• Toppings & overlays

• General-purpose concrete mixes

Fibrillated PP Fibers (Micro Synthetic Fibers)

Fibrillated polypropylene fibers have a mesh-like network created by splitting the fiber into interconnected fibrils. This structure increases mechanical anchorage within the cement paste.

Mesh Structure

• A fibrillated, “net-shaped” structure

• Creates a 3D reinforcing network

• Larger surface area than monofilament fibers

• Improved mechanical bond in fresh and hardened concrete

  
  

Advantages

• Better crack distribution

• Enhanced post-plastic performance

• Improved cohesion in mortar and plaster

Particularly beneficial in high-shrinkage mixes

Polyester (PET) Micro Synthetic Fibers

Polyester (PET) micro fibers offer higher modulus and better heat resistance compared to PP micro fibers, making them suitable for demanding mixes.

Chemical Resistance

• High resistance to acids, salts, and alkalis

• Very stable inside cementitious environments

• Excellent long-term durability and aging resistance

  
  

Typical Usage

• Mortar and plaster

• Repair materials

• Lightweight concrete

Decorative or architectural finishes

Ultra-Fine PP Micro Synthetic Fibers

Ultra-fine polypropylene fibers have diameters significantly smaller than standard micro fibers, creating an extremely high surface area.

High Surface Area

• Increases fiber-to-cement interaction

• Enhances cohesion of fresh concrete

• Improves resistance to early-age cracking

• Reduces bleeding and segregation

  
  

Finish Improvement

• Ideal for applications requiring smooth finishes

• Invisible after troweling

Common in thin toppings, overlays, UHPC, and grouts

Self-Dispersing PP Micro Synthetic Fibers

Self-dispersing PP fibers are engineered with surface treatments or layered strand structures to prevent clumping during mixing.

Mixing Performance

• Fast and uniform fiber distribution

• Reduced mixing time

• More consistent performance in ready-mix plants

  
  

No Balling

• Zero fiber ball formation

• High flow mixes benefit significantly

• Ideal for SCC, shotcrete, and precast batching systems

Learn more about HPM® PP polypropylene microfiber 

See all micro synthetic fiber types

Compare with macro synthetic fibers