What is micro reinforcement in concrete?

Micro reinforcement refers to very fine reinforcement elements distributed throughout the concrete matrix to control crack development and improve toughness.

What is fiber spacing theory?

Fiber spacing theory states that crack resistance in fiber reinforced concrete depends on the spacing between reinforcement elements. Smaller spacing increases crack interception probability.

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Rimix™ NanoRebar＞

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How Rimix™ NanoRebar Works

Name: Rimix™ NanoRebar
Brand: PIONEER®

Dense Distributed Micro Reinforcement for Concrete

Sales@pioneerfibre.com

Why Conventional Reinforcement Falls Short

Concrete cracking remains a persistent challenge in structural engineering. Conventional crack-control solutions such as polypropylene fibers and welded wire mesh can improve performance, yet their effectiveness is limited because reinforcement is not uniformly distributed throughout the concrete matrix.

Polypropylene fibers disperse within the concrete but provide limited stiffness after hardening. Welded wire mesh offers higher stiffness but exists only in a single horizontal plane, leaving most of the concrete volume unreinforced. Cracks can therefore still initiate and propagate through areas without effective reinforcement.

Dense Distributed Micro Reinforcement for Concrete

Rimix™ NanoRebar Reinforcement System →

Introducing Dense Distributed Micro Reinforcement

Rimix™ NanoRebar introduces dense distributed micro reinforcement, a new approach that places a large number of micro reinforcement elements throughout the concrete matrix.

Using ultra-fine high-strength micro fibers, NanoRebar forms a dense three-dimensional reinforcement network that significantly reduces reinforcement spacing and improves crack resistance, structural toughness, and overall concrete performance.

Rimix™ NanoRebar transforms conventional localized reinforcement into a dense distributed micro-reinforcement system within the concrete volume.

How NanoRebar Reinforces Concrete

When Rimix™ NanoRebar is mixed into concrete, ultra-fine micro fibers disperse throughout the cement matrix and create a dense network of micro reinforcement elements across the concrete volume.

Because reinforcement spacing is greatly reduced, developing cracks are far more likely to encounter reinforcement elements and be restrained at an early stage.

NanoRebar fibers also possess significantly higher tensile strength and elastic modulus than conventional polypropylene fibers, enabling them to bridge cracks and transfer tensile stresses effectively.

Through the combined effects of dense distributed reinforcement and efficient crack bridging, Rimix™ NanoRebar improves crack resistance, toughness, and structural performance in both the plastic and hardened stages of concrete.

Theoretical Basis: Fiber Spacing Theory

The theoretical basis of Rimix™ NanoRebar is fiber spacing theory, proposed by American researchers Romualdi and Batson in the 1960s and widely referenced in guidance from the American Concrete Institute (ACI).

The theory states that crack resistance in fiber-reinforced concrete largely depends on the average spacing between reinforcement elements.

When fibers are finer and more numerous, reinforcement spacing becomes smaller, increasing the likelihood that developing cracks will encounter reinforcement and be restrained.

By introducing a large number of ultra-fine fibers, Rimix™ NanoRebar forms a dense reinforcement network that significantly reduces reinforcement spacing and improves crack interception throughout the material.

Material Performance Comparison

The effectiveness of fiber reinforcement depends on two factors:

fiber mechanical properties
reinforcement spacing within the concrete matrix

Rimix™ NanoRebar utilizes ultra-fine polyacrylonitrile (PAN) micro fibers — the precursor material used in carbon fiber production — providing significantly higher strength and stiffness than conventional polypropylene fibers.

Property

Polypropylene Fiber

Rimix™ NanoRebar

Typical Fiber Diameter

20–48 μm

≈ 11 μm

Tensile Strength

300–450 MPa

600–900 MPa

Elastic Modulus

3–3.5 GPa

7–10 GPa

Recommended Dosage

0.9 kg/m³

0.45 kg/m³

Fiber Count per m³

≈ 0.6–1.0 Billion

≈ 2.7 Billion

introducing a large number of ultra-fine fibers

Laboratory Verification of Rimix™ NanoRebar

Independent laboratory testing compared Rimix™ NanoRebar with conventional polypropylene fiber reinforcement.

1. Crack Control

Mortar Type

Total Crack Area (mm²)

Crack Reduction (%)

Reference Mortar

1412.7

—

Polypropylene Fiber

415.3

70.6

Rimix™ NanoRebar

106.5

92.5

With 50% lower dosage, Rimix™ NanoRebar achieved 31% stronger crack control than polypropylene fibers.

2. Flexural Toughness

Concrete Type

Toughness Ratio Re

Improvement (%)

Reference Concrete

0.37

—

Polypropylene Fiber

1.57

324

Rimix™ NanoRebar

2.85

670

Compared with polypropylene fiber reinforcement, Rimix™ NanoRebar increases the flexural toughness ratio by 346%, significantly improving post-crack load capacity.

With 50% lower dosage, Rimix™ NanoRebar introduces 3–4 times more reinforcement elements per cubic meter, forming a much denser reinforcement network.

Engineering Value of Rimix™ NanoRebar

Rimix™ NanoRebar introduces a dense distributed reinforcement mechanism within the concrete matrix, transforming conventional localized reinforcement into a three-dimensional reinforcement system.

1. For Contractors

Replace conventional polypropylene crack-control fibers
Reduce or replace welded wire mesh
Eliminate mesh placement and tying work
Shorten construction schedules and improve efficiency

2. For Engineers and Designers

Provide crack control in both plastic and hardened concrete
Improve toughness and post-crack load capacity
Enhance impact resistance and structural performance
Enable higher-performance and more durable concrete structures

3. For Owners and Developers

Improve long-term durability and structural reliability
Reduce maintenance caused by cracking
Extend the service life of concrete structures
Achieve higher performance at a cost comparable to polypropylene fiber reinforcement

🔗 Contact Our Engineering Team →

FAQ

Micro reinforcement refers to the use of very fine reinforcement elements distributed throughout the concrete matrix to control crack development and improve toughness.
Rimix™ NanoRebar uses ultra-fine high-strength PAN micro fibers with significantly higher tensile strength and elastic modulus than conventional polypropylene fibers. The finer diameter allows billions of reinforcement elements to be distributed throughout the concrete.
Fiber spacing theory states that crack control effectiveness depends largely on the average spacing between reinforcement elements. Smaller spacing increases the likelihood that cracks will encounter reinforcement and be restrained.
In many applications, NanoRebar can reduce or partially replace welded wire mesh used for crack control, simplifying construction and improving efficiency.
Typical recommended dosage for Rimix™ NanoRebar is approximately 0.45 kg/m³, significantly lower than conventional polypropylene fiber reinforcement.

Ready to Upgrade Your Concrete Reinforcement?

Rimix™ NanoRebar introduces a new generation of dense distributed micro reinforcement, improving crack resistance, toughness, and durability of concrete while simplifying reinforcement systems.