| HS Code | 418566 |
| Material | Polypropylene |
| Fibertype | Macro synthetic |
| Form | Monofilament |
| Length | 54 mm |
| Equivalentdiameter | 0.9 mm |
| Aspectratio | 60 |
| Tensilestrength | 620 MPa |
| Elasticmodulus | 9.5 GPa |
| Specificgravity | 0.91 |
| Meltingpoint | 160 °C |
| Ignitionpoint | >400 °C |
| Alkaliresistance | Excellent |
| Acidresistance | Excellent |
| Saltresistance | Excellent |
| Waterabsorption | Nil |
| Dosage | 3 - 9 kg/m³ |
| Color | Natural |
| Corrosionresistance | Non-corroding |
| Electricalconductivity | Low |
| Thermalconductivity | Low |
| Magnetic | No |
| Uvresistance | Excellent |
| Numberoffibersperkg | Approximately 32,000 |
| Standardscompliance | ASTM C1116 Type III; EN 14889-2 Class I; ASTM C1609 |
As an accredited MasterFiber 241 SPA - Structural Macro Synthetic Polypropylene Fiber factory, we enforce strict quality protocols—every batch undergoes rigorous testing to ensure consistent efficacy and safety standards.
| Packing | MasterFiber 241 SPA comes in 20 kg moisture-resistant paper bags, palletized and shrink-wrapped for efficient storage and handling. |
| Container Loading (20′ FCL) | Container Loading (20′ FCL): MasterFiber 241 SPA structural macro synthetic polypropylene fiber, palletized, dry, securely stacked, within payload limits. |
| Shipping | MasterFiber 241 SPA ships as a non-hazardous, non-regulated article in sealed, moisture-resistant bags or cartons on pallets. Protect from moisture, contamination, and physical damage. Store in a cool, dry, ventilated area; keep packaging closed until use and avoid prolonged UV exposure. No special transport classification or placarding is required. |
| Storage | Store MasterFiber 241 SPA in original, unopened packaging in a dry, cool, well-ventilated area. Keep away from direct sunlight, heat, flames, moisture, and incompatible materials. Place on pallets, off the ground, to prevent contamination and package damage. Maintain stable temperatures and follow manufacturer/SDS guidance. Keep containers closed when not in use, avoid prolonged UV exposure and dust generation, and use FIFO stock rotation. |
| Shelf Life | Shelf life is 24 months from production when stored unopened, dry, at recommended temperatures, away from direct sunlight and moisture. |
Before a tunnel mix is approved for advance-rate-critical headings, the relevant acceptance parameter is not the fiber’s tensile strength in isolation but the round-panel energy absorption measured under ASTM C1550-20 and the residual flexural ratio obtained in ASTM C1609/C1609M-19a. MasterFiber 241 SPA structural macro synthetic polypropylene fiber is introduced into wet-mix sprayed concrete typically at 4.0–7.0 kg/m³, with the lower bound set by the energy absorption class required in EN 14487-1 and the upper bound governed by pumpability and rebound control. The choice between EFNARC energy absorption classes E500, E700, and E1000 at 25 mm central deflection drives the dosage and accelerator selection. On production-scale wet-mix lines, pressure pulsation can occur when fiber concentration and delivery-line diameter are poorly matched; positive-displacement machines with 48 mm delivery hoses require trial validation because the fiber network increases the plastic viscosity of the conveyed shotcrete. The batching sequence in a twin-shaft compulsory mixer places MasterFiber 241 SPA after aggregates and before cement slurry, which avoids the hydrophobic clumping observed when the fiber is added directly to high-shear water. For CE-marked permanent linings, the fiber falls within the scope of EN 14889-2:2006 Annex ZA, and the finished lining must also meet the sprayed-concrete conformity clauses of EN 14487-1 for compressive strength class, bond strength, and energy absorption. Fibers are not a direct substitute for welded wire mesh in all permanent arch linings; the design must reconcile early-age crack control with the post-crack flexural capacity of the macro-synthetic fiber network. Finished products from this process include primary tunnel linings, access adits, cross-passages, ventilation shafts, and portal collars. The process constraint that dominates this application is the interaction between accelerator dosage and fiber anchorage: high-alkali sodium silicate accelerators can produce a rapid stiffening that limits fiber pull-out redistribution, while alkali-free accelerators preserve more of the fiber’s post-crack energy transfer but can delay final set in cold tunnels with ambient temperatures below 5 °C. Automated dosing by loss-in-weight feeder is specified where batch-to-batch variation in residual strength would otherwise exceed the project tolerance.
In ground-supported industrial slabs, the governing failure mechanism before hardening is plastic settlement cracking at the surface, while after hardening it is restrained drying shrinkage combined with wheel loads and point loads from racking uprights. MasterFiber 241 SPA is batched at 2.5–5.0 kg/m³, and the mix design is adjusted with a water reducer to hold slump at 120–150 mm under ASTM C143/C143M while avoiding segregation. The industry compliance framework includes ACI 360R-10 for slab-on-ground design, ASTM C1609/C1609M-19a for flexural performance after first crack, and fiber conformity verified against EN 14889-2:2006. The relevant flatness and levelness specification is ASTM E1155/E1155M-20; where the specified FF number exceeds 35, the change in surface closure time produced by the fiber network requires a test strip with the actual power trowel equipment. In downstream production, the fiber is added at the ready-mix plant to a transit mixer after the initial concrete batch has been charged, then mixed at high drum speed for 5–7 minutes before leaving the batch plant. Placement by laser screed is followed by floating and pan finishing; the fiber network does not eliminate saw-cut joints but allows the designer to evaluate joint spacing against the residual strength ratio rather than relying only on unreinforced slab length. The completed slab types include warehouse floors, logistics hub slabs, distribution center ground slabs, cold store floor slabs, and apron hardstands where thermal shrinkage restraint is dominant. The operational boundary occurs when the slab moves into high-bay racking or heavy forklift applications requiring punching shear reinforcement or pile support; in such cases the macro-synthetic fiber is used as crack-control reinforcement, not as a substitute for structural steel or pile-supported slab design.
Because slope stabilization shotcrete is applied in vertical layers over irregular rock faces, the mix design must tolerate variable rebound and layer sag while maintaining bond to cleaned rock or soil. MasterFiber 241 SPA is typically dosed at 4.0–6.0 kg/m³ in these facings; EN 14889-2:2006 applies to the fiber before site acceptance, and the application requirements are set by EN 14487-1 and ACI 506R-16, with energy absorption verified by ASTM C1550-20. Downstream production uses a wet-mix shotcrete machine with air-assisted nozzle discharge, and the mix is shot at 6–10 m³/min air volume at the nozzle to prevent pulsation in vertical application. The process sequence is sensitive to surface preparation: loose rock is scaled, soil nail heads are recessed or covered, and the first pass is sprayed at 25–40 mm thickness before the final profile is built in sequential passes not exceeding 100 mm per pass. Constructed products from this class include soil nail facings, rockfall retention panels, erosion-control linings, and surface drainage channel linings. The limitation is that permanent slope facings exposed to high-velocity debris flow require additional anchorage and design validation because the macro-synthetic fiber contribution is to post-crack flexural toughness, not to the tensile capacity of the ground anchor system.
When precast concrete pipe manufacturing shifts from traditional reinforcing cage assembly to fiber-reinforced wet-cast production, the fiber addition must be evaluated against the compaction energy available in the vertical casting station. MasterFiber 241 SPA is introduced into the mix at 3.0–6.0 kg/m³ for concrete pipes and box culverts, with product conformity established under EN 1916:2002 for concrete pipes and fittings, while North American external load classes are governed by ASTM C76 or ASTM C1433 depending on the pipe or culvert category and the fiber contribution is evaluated separately by ASTM C1609/C1609M-19a. The downstream production process uses wet-cast vertical pipe forms with core vibrators and external form vibrators; the fiber is dosed into the pan mixer after fine aggregate has been added to prevent balling in the low-water mix. A key process bottleneck is the narrow balance between water content and fiber dispersion: too dry a mix prevents fiber from orienting uniformly, while too wet a mix reduces the green strength required for immediate demolding. The cast outputs are stormwater pipes, gravity sewer pipes, culvert sections, and box culverts for rural road crossings. The operational boundary is that flexural load classes still require reinforcement design according to the pipe standard; macro-synthetic fiber contributes to crack-width control and handling resistance but is not an automatic substitute for steel reinforcement in all load-bearing classes.
In precast manhole production, the decision to remove secondary steel reinforcement and replace it with macro-synthetic fiber depends on the hoop stress, hydrostatic pressure, and installation depth of the structure. MasterFiber 241 SPA is added at 3.0–5.0 kg/m³ in wet-cast manhole base sections, risers, and utility vault panels, with dimensions and load classes aligned to ASTM C478-20 for circular precast manhole sections where steel remains in hoop zones and to EN 13369:2018 for common precast concrete rules. CE marking under EN 14889-2:2006 applies to the fiber itself. The downstream process uses steel forms with internal vibrators and a curing chamber operating between 40 °C and 60 °C; fiber addition is made after cement and aggregate have been mixed but before the final water adjustment, ensuring the fiber does not float to the top surface in superplasticized mixes. Production bottlenecks include fiber accumulation around vibrator pockets and the inability to re-strike the form after initial vibration without sacrificing fiber distribution. The resulting precast components include circular manhole base sections, riser rings, valve vault walls, catch basin structures, and utility pull-boxes. The limiting condition occurs in deep installations with high groundwater pressure, where the design must retain steel reinforcement for hoop strength because the macro-synthetic fiber provides post-crack residual flexural capacity but not the same tensile reinforcement area as deformed steel bar.
Crack-width control in water-retaining concrete structures is governed by the serviceability limits of ACI 350-20 and the water tightness criteria of EN 1992-3, not only by compressive strength. MasterFiber 241 SPA is batched at 3.0–5.0 kg/m³ in cast-in-place clarifier walls, pump station slabs, and channel linings; the fiber is tested under the conformity requirements of EN 14889-2:2006, and flexural performance after first crack is quantified by ASTM C1609/C1609M-19a. The downstream production process places the concrete by pump boom into formwork with rebar cages spaced at 25–50 mm; macro-synthetic fiber can displace water at the form face during high-frequency poker vibration, so the vibration interval is shortened to avoid fiber bleed. The finished concrete elements are wastewater clarifier tank walls, pump station wet wells, stormwater detention vaults, and screening channel linings. Published data for this specific configuration in watertight structures is limited, and a site-specific trial pour is required to confirm that the selected dosage does not compromise the water-cement ratio or the consolidation specification. The operational limitation is that the fiber does not replace waterstops or joint sealing systems; continuity at construction joints is maintained by those systems, while the fiber addresses distributed microcracking between joints.
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MasterFiber 241 SPA is a structural macro synthetic polypropylene fiber supplied in collated bundles that separate into discrete fibers during concrete mixing. The material is intended for cast-in-place slabs, precast elements, pavements, and wet-mix shotcrete where distributed post-crack reinforcement is required. Under ASTM C1116/C1116M, the fiber is classified as a Type III synthetic fiber-reinforced concrete material; this classification separates the product from microsynthetic fibers used primarily for plastic shrinkage control. The model designation MasterFiber 241 SPA identifies a macro synthetic product, not a steel fiber or a monofilament microfiber. Product specifications include the model designation, fiber classification, dosage range by concrete mass, and the test standards used for compliance. The product is manufactured from virgin polypropylene with a specific gravity near 0.91, which is markedly lower than the 7.85 typical for steel fiber. Published product-specific fiber length, tensile strength, and elastic modulus are contained in the regional technical data sheet; however, structural macro synthetic polypropylene fibers of this class commonly exhibit tensile strengths in the 550–700 MPa range and elastic moduli in the 5–10 GPa range.
Recommended dosages for slab-on-ground applications typically fall between 1.8 kg/m³ and 4.5 kg/m³. Heavy-duty pavements, tunnel linings, and high-toughness precast applications may require dosages up to 6.0 kg/m³ or higher only when confirmed by preconstruction testing. The fiber is non-corrosive, resistant to alkali hydrolysis, and does not cause rust staining, which differentiates it from steel fiber reinforcement in exposed surfaces. Published data for this specific configuration is limited when the regional technical data sheet is not available; contract specifications should therefore require performance verification using the relevant residual strength standard.
MasterFiber 241 SPA functions primarily through mechanical anchorage and fiber-to-matrix pullout resistance after concrete cracking. The fiber does not have the elastic modulus of steel; the engineering function is crack-width control and post-crack residual load transfer rather than elastic stiffness parity. The product is normally specified where conventional welded wire mesh or light rebar is used for temperature and shrinkage reinforcement, or where steel fibers introduce handling, corrosion, or rebound concerns. The fiber's lower density means that a given mass dosage creates a higher fiber count than the same mass of steel. The cross-sectional crack-bridging efficiency depends on length, equivalent diameter, aspect ratio, and dosage. Typical aspect ratios for this class are between 60 and 80; higher aspect ratios increase pullout resistance but can reduce workability if dosage is high.
In practice, MasterFiber 241 SPA is added by mass to the concrete batch. The fiber dosage is not a direct replacement for mesh by area because mesh area and wire spacing define a different crack-control mechanism. The fiber distributes reinforcement throughout the matrix in three dimensions, whereas mesh reinforcement lies in a defined plane. This difference is important in slabs with top and bottom cover zones: if mesh is misplaced or pressed to the bottom of the slab, its crack-control efficiency can be degraded, whereas the fiber is distributed throughout the full depth if mixing is adequate.
| Property or parameter | Microsynthetic fiber | MasterFiber 241 SPA class | Hooked-end steel fiber |
|---|---|---|---|
| Typical dosage | 0.6–1.2 kg/m³ | 1.8–6.0 kg/m³ | 20–40 kg/m³ |
| Specific gravity | 0.90–0.92 | 0.90–0.92 | 7.85 |
| Tensile strength | 300–450 MPa | 550–700 MPa | 1000–1500 MPa |
| Elastic modulus | 3–5 GPa | 5–10 GPa | 200 GPa |
| Corrosion in chloride service | None | None | Surface corrosion possible if exposed |
| Primary function | Plastic shrinkage crack reduction | Post-crack residual strength and crack-width control | High post-crack toughness and strength |
The MasterFiber 241 SPA column represents the structural macro synthetic class. Product-specific datasheet values supersede these class ranges.
At lower dosages, the crack-bridging fiber count is not always sufficient for repeatable post-crack performance. Below 2.0 kg/m³, the material may act mainly as a crack-width control system and provides limited residual load capacity in normal-weight concrete. When the dosage increases to 3.0 kg/m³ and above, the fiber count intersecting a crack plane in a 150 mm × 150 mm beam section becomes high enough to support measurable residual loads after matrix cracking, provided mixing achieves full dispersion. The transition is not abrupt; aggregate size, slab thickness, fiber orientation, and concrete strength shift the effective dosage. Workability typically decreases at dosages above 4.0 kg/m³, and water-reducing or high-range water-reducing admixtures are often required to maintain target slump without increasing water-cementitious material ratio.
ASTM C1609/C1609M reports load-deflection data from 150 × 150 × 500 mm beams under third-point loading. The residual strengths f600 and f1000 are expressed as equivalent modulus of rupture at net deflections of L/600 and L/150. A macro synthetic fiber concrete with 3.0–5.0 kg/m³ dosage may produce a measurable but relatively low f600 value compared with hooked-end steel fiber at high dosage; the same mix can maintain load capacity at larger deflections due to fiber pullout behavior. For European specifications, EN 14651 defines residual flexural tensile strength values fR,1 and fR,3 at crack mouth opening displacement values of 0.5 mm and 2.5 mm. The product class typically exhibits fR,1 that is sensitive to fiber orientation and matrix strength, while fR,3 is more dependent on fiber length and anchorage. Published data for MasterFiber 241 SPA in these exact test configurations is limited; preconstruction beam or panel tests are required for performance-based specifications.
Performance equivalence is not established by equal mass or even equal volume fraction. A hooked-end steel fiber dosage of 25 kg/m³ at a density of 7.85 corresponds to approximately 0.32% by volume; a macro synthetic dosage of 3.0 kg/m³ at a density near 0.91 corresponds to approximately 0.33% by volume. Despite similar volume fractions, the cracked-section stiffness differs because steel has an elastic modulus near 200 GPa and polypropylene has an elastic modulus in the 5–10 GPa range. Consequently, early post-crack strength at small crack openings is normally lower for macro synthetic fiber concrete unless the design accounts for crack-width-dependent residual strength. Replacement of steel fiber should be based on ASTM C1609/C1609M flexural performance classes or EN 14651 residual strength classes, not on mass-per-volume substitution.
Where welded wire mesh is used only for temperature and shrinkage crack control, MasterFiber 241 SPA may simplify placement by eliminating the need for chairs, laps, and cover clearance. The fiber does not provide the same bar-to-bar continuity as deformed steel bars in high-moment regions. In slab-on-ground applications, joint spacing and load-transfer design remain critical because the fiber does not eliminate drying shrinkage and does not replace dowels at contraction joints. The concrete must still be sawcut at the specified spacing and depth; sawcut timing is governed by the same early-age shrinkage characteristics as plain concrete. Published data for this specific configuration is limited when the slab design relies on traditional tensile strength assumptions.
| Purpose | Standard or code |
|---|---|
| Synthetic fiber classification | ASTM C1116/C1116M Type III |
| Flexural performance of fiber-reinforced concrete | ASTM C1609/C1609M |
| Residual flexural strength of macro fiber concrete | EN 14651 |
| Fiber-reinforced concrete quality management | ISO 9001:2015 |
| Round panel energy absorption for shotcrete | ASTM C1550 |
These standards should be written into concrete specifications when structural performance is required. The contract should state the required residual strength class, test age, beam or panel dimensions, and fiber dosage range. Preconstruction testing should use the same concrete mix, batching sequence, and placement method intended for production. Conformance with ASTM C1116/C1116M Type III alone is not sufficient to establish structural equivalency because that classification does not quantify post-crack residual strength. The inclusion of ASTM C1609/C1609M or EN 14651 performance requirements prevents substitution of a microfiber or a non-structural macrofiber that has not been tested for load-carrying capacity after cracking.
For central-mix plants, MasterFiber 241 SPA should be added with aggregates or on a conveyor belt so that the fibers are drawn into the mixer under aggregate impact. In twin-shaft mixers, the bundles separate quickly; in low-shear drum mixers, clumping can occur at dosages above 3.0 kg/m³. Extended wet mixing is required after all ingredients are charged until visual inspection confirms discrete fiber distribution. For wet-mix shotcrete, the fiber is batched at the plant and pumped through delivery lines. Macro synthetic fiber addition can increase line pressure compared with plain shotcrete, and the nozzle diameter and pump configuration must be compatible with the fiber length. Rebound is generally lower than that of steel fiber on a mass basis, but the required energy absorption class must be confirmed using ASTM C1550 round panel tests or equivalent project specifications.
During finishing, fibers at the slab surface may be oriented by the vibratory screed or long-handled bull float; the final troweling sequence can press fibers into the paste or leave minor fiber print-through on hard-trowel surfaces. This condition does not indicate poor concrete quality but may require additional pan passes or surface treatment if a smooth appearance is specified. The product does not change hydration kinetics, but at high dosage the increase in fresh concrete viscosity may require longer vibration or higher poker vibrator frequency for precast molds with congested form details.
In chloride-containing service conditions, the polypropylene matrix remains non-corroding, which differentiates the fiber from steel fibers that may produce surface discoloration at exposed cracking. The material is not a replacement for primary reinforcement in beams, columns, or structural frames unless specifically designed using provisions for fiber-reinforced concrete and validated by full-scale testing. At temperatures above the polypropylene softening range near 160 °C to 170 °C, the fiber softens and loses load-bearing capacity, although the melted channels may assist in fire-spalling mitigation. Storage should be dry and covered; although polypropylene does not absorb water, wet or tightly compacted bags may exhibit clumping that affects fiber feeding in automatic dispensers.
