STRUX® M323 Synthetic Fiber Blend

Synthetic Macro and Micro Fiber blend for reinforcement of concrete

Product Description

STRUX® M323 is a blended synthetic fiber complying with ASTM C1116/C1116M Type III, which can be used in ready-mixed concrete for different applications such slab-on-ground flooring, topping slabs and bridge decks. It consists of a combination of 3 lbs. (1.36kg). STRUX® 75/32 macrofibers and 1 lb. (0.45kg). SINTA® M3019 microfibers. The STRUX® M323 Synthetic Fiber Blend has been specifically engineered to provide improved performance in both the plastic and hardened concrete state.

STRUX® M323 Synthetic Fiber Blend is extruded from a virgin polypropylene and polyethylene polymer blend. The geometry, blend ratio, strength and high modulus is specifically engineered to provide high post-crack control performance with excellent dispersion into the concrete matrix, reducing plastic and hardened concrete shrinkage cracking, and increasing fatigue resistance and concrete toughness. STRUX® M323   Synthetic Fiber Blend has been specifically engineered to be a user-friendly fiber reinforcement.

Compliance and Certification

  • ASTM C1116 / C1116M, Standard Specification for Fiber-Reinforced Concrete, Type III Synthetic Fiber-Reinforced Concrete
  • ASTM D7508 / D7508M, Standard Specification for Polyolefin Chopped Strands for Use in Concrete
  • ANSI/SDI C-2017, Composite Steel Floor Deck Slabs (Section 2.4.B.15.a.3)

Product Advantages

  • Can be used to completely or partially replace light rebar, welded wire reinforcement and steel fibers.
  • Easy to mix and fast to disperse.
  • Barely visible on the surface obtaining highly aesthetic concrete.
  • Saves money through reduction or elimination of steel labor and materials, transportation, delivery and jobsite storage, reduced special inspections, and fewer construction days.
  • Enhances safety by eliminating handling of steel fibers, welded wire reinforcement or rebar.
  • Enhances jobsite safety by eliminating tripping hazards commonly associated with welded wire reinforcement and distributed steel rebar reinforcement.
  • Eliminates concerns of proper positioning of steel reinforcement.
  • Due to unique fiber design and uniform three dimensional dispersion, both plastic as well as drying shrinkage cracking is reduced, improving the ductility and durability of the concrete.
  • Provides superior crack control due to the geometry and elastic modulus, corrosion resistant properties (non-ferric).
  • Ease of pumping, passes easily through pump grates.
  • May be used to provide effective crack width control.

Primary Applications

STRUX® M323 Synthetic Fiber Blend may be used in a variety of ready mix and precast applications including Bridge decks, residential and commercial slab-on-ground flooring, thin and conventional whitetoppings and overlays, and pavements.

Bridge Decks:
STRUX® M323 Synthetic Fiber Blend has been specially designed for ease of use, rapid dispersion, excellent finishability and improved pumpability in bridge decks.

Traditional light steel reinforced elements: 
STRUX® M323 Synthetic Fiber Blend can be used as a suitable alternative to WWF or light reinforcing steel specified for temperature and shrinkage reinforcement.

Whitetoppings and overlays 
STRUX® M323 Synthetic Fiber Blend is ideal for whitetoppings and overlays. Due to its superior performance in the field, rapid dispersion into the mixture and ease of finishability, the overall project productivity and contractor’s profitability is enhanced.

Addition rates

STRUX® M323  Synthetic Fiber Blend addition rates are dependent on the specific application and desired properties and will typically vary between 4 to 7.5 lbs./yd3 (1.8 to 4.5 kg/m3),   Please consult your GCP Applied Technologies sales representative for proper addition rate of STRUX® M323  Synthetic Fiber Blend for your application. Always consult local building codes. 

Guidelines for Usage and Compatibility with Other Admixtures

The utilization of STRUX® M323 Synthetic Fiber Blend may require the use of a mid-range water reducer or a high-range water reducer such as MIRA® or ADVA® families of admixtures to restore the required workability. In addition, slight increases in fine aggregate contents may be needed. STRUX® M323  Synthetic Fiber Blend may be added to concrete at any point during the batching or mixing process.

STRUX® M323  Synthetic Fiber Blend are compatible with all GCP admixtures. Their action in concrete is mechanical and will not affect the hydration process of the cement or compressive strength. Each liquid admixture should be added separately to the concrete mixture.

STRUX® M323  Synthetic Fiber Blend PHYSICAL PROPERTIES

Synthetic Macro Fiber:

Specific gravity 0.92
Absorption None
Modulus of elasticity 1,389 ksi (9.5 GPa)
Tensile strength 90 ksi (620 MPa) 
Melting point 320°F (160°C)
Ignition point 1,094°F (590°C)
Alkali, acid & salt resistance High
Material 100% virgin polypropylene and polyethylene blend
Electrical and Thermal Conductivity Low
Nominal Length 1.25 in. (32 mm) 
Nominal Aspect Ratio (Macrofiber) 75
Nominal Equivalent Diameter (macrofiber) 0.017 in. (0.43 mm)
Nominal Fiber Count  106,400 per lb (233,600 per kg) / 30 million per lb

Micro fibers Typical Properties

Specific gravity 0.91
Absorption None
Modulus of elasticity 500 ksi (3.45 GPa)
Tensile Strength 15.6 ksi (108 MPa)
Melt point 320°F (160°C)
Ignition point 1094°F (590°C)
Alkali, acid and salt resistance High
Material 100% virgin polypropylene
Nominal Length 0.75 in. (19 mm)
Nominal Fiber Count 30 million per lb.


STRUX® M323  Synthetic Fiber Blend reinforced concrete bridge decks can be finished with most finishing techniques. Due to its characteristics STRUX® M323  Synthetic Fiber Blend are suitable to be used in power/hand troweled concrete, colored and broom finished concrete. Impact on finishability increases with dosage rate and should be evaluated by the contractor to determine the impact on finishability with the proposed concrete mixture proportions


STRUX® M323  Synthetic Fiber Blend is available in 4 lb. (1.8 kg) bags

Safety and Handling

Read and understand the product label and Safety Data Sheet (SDS). All users should acquaint themselves with this information prior to working with the products and follow the precautionary statements. SDSs can be obtained by contacting your local GCP representative or office.

U.S. Patent No. 6,569,525
U.S. Patent No. 6,569,526
U.S. Patent No. 6,758,897
U.S. Patent No.  6,863,969 | North America customer service: 1-877-4AD-MIX (1-877-423-6491)

We hope the information here will be helpful. It is based on data and knowledge considered to be true and accurate and is offered for consideration, investigation and verification by the user, but we do not warrant the results to be obtained. Please read all statements, recommendations and suggestions in conjunction with our conditions of sale, which apply to all goods supplied by us. No statement, recommendation or suggestion is intended for any use that would infringe any patent, copyright or other third-party right. 

ADVA, MIRA, and STRUX are trademarks, which may be registered in the United States and/or other countries, of GCP Applied Technologies Inc. This trademark list has been compiled using available published information as of the publication date and may not accurately reflect current trademark ownership or status.

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GCP Applied Technologies Inc., 2325 Lakeview Parkway, Suite 475, Alpharetta, GA 30009, USA
GCP Canada, Inc., 294 Clements Road, West, Ajax, Ontario, Canada L1S 3C6.
This document is only current as of the last updated date stated below and is valid only for use in the Canada. It is important that you always refer to the currently available information at the URL below to provide the most current product information at the time of use. Additional literature such as Contractor Manuals, Technical Bulletins, Detail Drawings and detailing recommendations and other relevant documents are also available on Information found on other websites must not be relied upon, as they may not be up-to-date or applicable to the conditions in your location and we do not accept any responsibility for their content. If there are any conflicts or if you need more information, please contact GCP Customer Service.

Last Updated: 2024-06-21