| HS Code | 674263 |
| Product Name | MICROFIBER - Monofilament Polypropylene Fiber, 12 mm |
| Material | 100% Polypropylene |
| Fiber Type | Monofilament |
| Length | 12 mm |
| Diameter | 18-30 µm |
| Aspect Ratio | 400-667 |
| Specific Gravity | 0.91 |
| Density | 0.91 g/cm³ |
| Melting Point | 160-170 °C |
| Softening Point | Approximately 150 °C |
| Ignition Point | >350 °C |
| Tensile Strength | 300-400 MPa |
| Elastic Modulus | 3.5-5.0 GPa |
| Elongation At Break | 15-30% |
| Acid Resistance | High |
| Alkali Resistance | High |
| Water Absorption | Negligible / hydrophobic |
| Thermal Conductivity | Low |
| Electrical Conductivity | Low / non-conductive |
| Color | Natural white |
| Form | Monofilament fiber |
| Recommended Dosage | 0.6-1.8 kg/m³ |
As an accredited MICROFIBER - Monofilament Polypropylene Fiber, 12 mm factory, we enforce strict quality protocols—every batch undergoes rigorous testing to ensure consistent efficacy and safety standards.
| Packing | MICROFIBER 12 mm is supplied in 20 kg moisture-resistant paper bags on shrink-wrapped pallets, 40 bags per pallet. |
| Container Loading (20′ FCL) | 20′ FCL stuffing: 12 mm monofilament polypropylene microfiber, bagged and palletized, dry container, evenly distributed, securely braced for safe transport. |
| Shipping | Non-hazardous, non-regulated for transport. Ship in moisture-resistant bags or woven sacks, palletized and shrink-wrapped. Keep dry, avoid contamination and open flames. Use standard truck or container freight. No special transport labels required. Handle with normal PPE and avoid puncturing packaging. Store in a cool, dry, ventilated area. Suitable for general cargo. |
| Storage | Store in a cool, dry, well-ventilated area away from direct sunlight, heat, sparks, flames, and strong oxidizers. Keep original containers or bags sealed, clean, and dry; stack on pallets to prevent moisture and damage. Avoid airborne dust and static discharge. Protect from physical damage, store separately from incompatible materials, and follow SDS/local regulations. |
| Shelf Life | Indefinite shelf life if stored in a cool, dry, ventilated area, away from direct sunlight and moisture, in original packaging. |
Addition of 12 mm monofilament polypropylene fiber at 0.9 kg/m³ to a C30/37 concrete with 20 mm maximum aggregate is performed in a central twin-shaft compulsory mixer. The fiber is introduced to the sand and coarse aggregate stream before 70% of the mixing water has entered the mixer. Residual mixing time after fiber addition is extended by 30–60 s compared with the plain control. This placement is specified for pump-placed internal slabs, external hardstands, and composite steel deck toppings. Under ASTM C1116/C1116M Type III classification, the fiber is a synthetic micro-fiber for plastic shrinkage crack control, not a structural macro-fiber. Laboratory panels tested according to ASTM C1579-21 show crack-area reduction in the range of 60–85% at 0.9 kg/m³, with residual cracking typically localized in a single restrained crack rather than distributed map cracking. Slump measured to ASTM C143/C143M typically falls by 10–20 mm at this dosage in a 120–150 mm target mix. Addition rates above 1.8 kg/m³ produce steeper slump loss and lower pumpability in truck-mounted boom pumps operating at outlet pressures of 60–80 bar. Air content measured to EN 12350-7:2019 can decrease by 0.5–1.0 percentage point when the same batch contains an air-entraining admixture; plants compensate by increasing the air-entraining agent dose by 0.05–0.15% by mass of cement to maintain 5–6% air. Batch records from production lines show fiber balling is initiated when fiber is added directly to water, when mixer paddle tip speed exceeds 2.5 m/s, or when residual mixing time is below 30 s. Storage silos and hopper covers should remain closed above 85% relative humidity because surface moisture on fiber bundles increases balling tendency. The 12 mm length is compatible with 20 mm maximum aggregate but is not recommended for concrete containing aggregate larger than 25 mm because fiber entanglement at the aggregate surface increases. Under ASTM C1399/C1399M, average residual strength at 0.9 kg/m³ remains below 0.1 MPa, which confirms that the product provides no post-crack structural flexural capacity and cannot replace welded wire reinforcement for load-bearing crack control.
Precast concrete pipe and manhole production running dry-cast mixes with a water-cement ratio of 0.30–0.38 and a slump of 0–20 mm uses the fiber at 0.9–1.2 kg/m³. In a planetary counter-current mixer, the fiber is added to the dry aggregate before cement and water. Compaction is performed on a vibrating station with external clamp vibrators operating at 50–70 Hz and a compaction time of 30–60 s. Batch records show lower surface repair time on the finishing line when fiber is present at 0.9–1.2 kg/m³, particularly at the spigot-to-barrel transition and at the socket shoulder where abrupt section changes create differential green strength. Products are verified to EN 1916:2002+A1:2019 for concrete pipes and manholes and to EN 206:2013+A2:2021 for the base concrete family. Fiber conformity is assessed under EN 14889-2:2006 as a polymer fibre for concrete. Fiber balling is the controlling defect: production records show clumps form when residual mixing time is below 30 s after fiber addition or when aggregate moisture content exceeds 0.5% by mass because fiber sticks to wet sand surfaces. The 12 mm length is acceptable for dry-cast mixes with 8–14 mm maximum aggregate; above 16 mm maximum aggregate, visible fiber bundles can appear on the pipe barrel after demolding. The dosage does not affect the required crushing strength class or the hydraulic tightness test, but it reduces early-age crack-related reject rates. The product is not used in prestressed concrete cylinder pipe or in pipe mixes where high-frequency core compaction exceeds 80 Hz, because excessive vibration can float lower-density polymer fiber toward the inner mold surface. Steam curing at 60–80°C for 12–16 h does not melt the fiber or close the crack-control function.
In wet-mix tunnel shotcrete, the 12 mm monofilament PP fiber is added at 1.0–1.5 kg/m³ to a pumpable mix with 8 mm maximum aggregate and a slump of 180–220 mm before accelerator addition. Mixing takes place in a twin-shaft or planetary mixer; fiber is added after superplasticizer but before or during aggregate addition to avoid dry fiber accumulation on moist mixing blades. The mix is conveyed by a swing-tube piston pump rated at 20–30 m³/h through a 100–125 mm delivery line. Alkali-free accelerator is injected at the nozzle at 4–7% by mass of cement. Site monitoring reports from tunnel projects record rebound reductions in the range of 2–6 percentage points at 1.2 kg/m³ on vertical and overhead sections compared with the plain reference mix, but rebound remains dominated by nozzle angle, accelerator dosage, and aggregate grading. The fiber length must not exceed 1.5 times the maximum aggregate size; therefore 12 mm fiber is incompatible with shotcrete containing 10 mm or larger aggregate. Hose routing requires a minimum bend radius of 300 mm; tighter 90° bends create fiber accumulation at the inside radius and produce pulsation at the nozzle. For fire-resistant linings, the terminal function changes: the fiber melts at 160–170°C and leaves capillary channels that relieve pore pressure in dense high-performance concrete. This spalling-control mechanism is relevant when the lining is evaluated under EN 1991-1-2 hydrocarbon fire curves or project-specific RWS curves. Non-uniform fiber distribution is a critical failure mode because local areas without channels may spall explosively. Production verification includes washing out fiber from fresh shotcrete and checking clump mass below 0.1% of total fiber mass. Conformity of the shotcrete is assessed to EN 14487-1:2022 and the fiber to EN 14889-2:2006.
| Application segment | Typical addition rate | Critical limiting parameter | Primary standard |
|---|---|---|---|
| Ready-mix slab-on-grade | 0.9 kg/m³ | Maximum aggregate 20 mm; addition above 1.8 kg/m³ causes slump loss | ASTM C1116/C1116M Type III |
| Precast concrete pipe and manhole | 0.9–1.2 kg/m³ | Aggregate moisture ≤0.5%; vibration frequency ≤80 Hz | EN 1916:2002+A1:2019, EN 14889-2:2006 |
| Wet-mix tunnel shotcrete | 1.0–1.5 kg/m³ | Maximum aggregate 8 mm; hose bend radius ≥300 mm | EN 14487-1:2022 |
| Flowing floor screed | 0.6–1.0 kg/m³ | Layer thickness ≥25 mm | EN 13813:2021 |
| Exterior render base coat | 0.5–0.9 kg/m³ | Base-coat thickness ≥12 mm; mixing speed ≤600 rpm | EN 998-1:2016 |
| Dense refractory castable | 0.1–0.5 kg/m³ | Dry-out heating rate ≤25°C/h below 300°C | Project-specific panel; no single harmonised fibre standard |
Flowing screed production with a CT-C25-F5 calcium sulfate dry-mix at 0.6–1.0 kg/m³ requires a continuous mixer-pump with a rotor-stator pump and a flow table diameter of 220–250 mm according to EN 12350-5. The 12 mm monofilament is added to the dry binder-aggregate stream before the mixing water to avoid hydrophobic fiber segregation. The minimum layer thickness is 25 mm for bonded and unbonded screeds and 35 mm over underfloor heating pipes, so the fiber length remains below 1/2 of the cover depth. Fiber addition reduces surface plastic shrinkage cracking at door thresholds, pipe penetrations, and floor drains where restrained drying stresses concentrate. For layer thickness below 20 mm, 12 mm fibers protrude from the trowel finish and produce surface fuzz; the production line switches to 6 mm filament for thin self-leveling underlayments. Pump strain and hose pressure remain stable at fiber dosage up to 1.0 kg/m³; above this value, rotor-stator pump wear accelerates and hose blockages at 25 mm internal diameter couplings become more frequent. Hardened screeds are tested to EN 13813:2021 for flexural strength, surface indentation, and drying shrinkage; the fiber does not alter the declared strength class but it reduces early-age crack count before floor covering installation. In gypsum-based mixes, the product is compatible with retarders and citric acid-based set modifiers; it must not be combined with unneutralized acidic additives that could embrittle the polymer surface or with organic solvents used in moisture-control layers.
At 0.5–0.9 kg/m³ in a masonry base coat specified to EN 998-1:2016, the 12 mm monofilament is mixed in a high-shear paddle mixer operating at 400–600 rpm. The fiber is introduced after the initial mixing water has combined with the premix, and mixing continues for 60–90 s. The base coat must be at least 12 mm thick; finish coats below 5 mm are excluded because fiber ends can pierce the floated surface. The fiber does not replace alkali-resistant glass fiber mesh in external thermal insulation composite systems; impact resistance and crack redistribution in those systems depend on the mesh geometry, not on the PP monofilament. Terminal use is two-coat render on clay brick or autoclaved aerated concrete. Application by spray mortar machine with a 10–15 mm nozzle is compatible at dosage below 0.8 kg/m³; above that, the nozzle can accumulate fiber at the air cap and produce spitting.
Dense low-cement refractory castables containing tabular alumina, calcined bauxite, calcium aluminate cement, and microsilica receive 12 mm monofilament PP fiber at 0.1–0.5 kg/m³ in a planetary mixer. The fiber is dry-blended with the refractory aggregate before water addition to prevent hydrophobic agglomeration. Mixing water is held at 5–7% by weight; the wet mix is vibrated into forms on a vibratory table at 40–60 Hz. During dry-out, the fiber melts at 160–170°C and leaves capillary channels that increase permeability before the castable reaches its first high-temperature firing. The dry-out heating rate below 300°C must not exceed 25°C/h; faster heating causes entrapped steam pressure to exceed the green strength of the castable before the polymer channels are fully open. Terminal products include ladle covers, kiln quay blocks, burner blocks, and petrochemical fired heater linings. In service, the remnant channels lower the risk of explosive spalling during the first heat-up cycle. The fiber does not contribute to cold crushing strength after burnout and must not be used in carbon-containing systems where reducing atmosphere prevents complete oxidation. Published data for this specific configuration is limited to manufacturer dry-out graphs and field heat-up records; no single harmonized EN product standard covers PP fiber in refractory castables, so the fiber is validated by project-specific spalling test panels.
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The product identified as MICROFIBER - Monofilament Polypropylene Fiber, 12 mm is a discrete synthetic microfiber intended for addition to cementitious matrices. The designation MICROFIBER-12/PP-M appears in batch control documentation: the numeric suffix identifies a cut length of 12 mm, the letter group PP denotes polypropylene, and the final character M denotes monofilament geometry. The fiber is manufactured by high-speed extrusion of virgin polypropylene followed by precision cutting of continuous monofilament filaments. The nominal specific gravity is 0.91, the melting point falls between 160 °C and 170 °C, and the published diameter range is 18–40 μm depending on production batch. The fiber is added to concrete, mortar, screed, and wet-process shotcrete at dosages commonly between 0.6 kg/m³ and 1.5 kg/m³, depending on exposure conditions, placement method, and mixture water content. The product falls under ASTM C1116/C1116M-23 as a Type III synthetic fiber-reinforced concrete component and is covered by the general requirements of EN 14889-2:2006 for polymer fibers for concrete. Unlike fibrillated polypropylene fibers, the monofilament form has a circular or near-circular cross-section and is not opened into a web; this geometry affects anchorage, mixing-energy demand, surface finish, and plastic-state crack control.
Plastic shrinkage crack control for synthetic microfiber systems is commonly evaluated using ASTM C1579-21. Laboratory studies on synthetic microfibers have reported crack area reductions of 50–80% at 0.9 kg/m³ relative to plain control slabs, but results for this specific 12 mm monofilament configuration are mixture-dependent and cannot be transferred across cementitious systems without trial batching. The product is not intended as load-bearing reinforcement and does not replace structural reinforcing bars under ACI 318-19 or EN 1992-1-1.
The primary processing risk for monofilament polypropylene fiber at 12 mm length is non-uniform distribution in low-water concrete. In twin-shaft compulsory mixers with batch volumes of 0.5–1.0 m³, clumping is more frequently observed when the water-cement ratio falls below 0.40. The fiber should be added to the aggregate after batching but before water addition. A dry-mix period of 30–60 s disperses the filaments through aggregate impact and prevents direct contact between dry fiber and cement paste. Wet mixing should continue for 4–5 min at the mixer manufacturer’s rated speed. Direct addition of fiber to cement paste or slurry can cause balling because the monofilament surfaces have insufficient aggregate contact to separate individual filaments.
Electrostatic charge on monofilament surfaces can promote agglomeration during dry conveying. Storage at relative humidity above 60% may increase surface moisture, reduce flowability, and alter feed behavior in pneumatic dosing equipment. The fiber should be kept in sealed packaging until use and allowed to equilibrate to ambient plant conditions before charging. Production-scale experience with pneumatic dosing indicates that low air pressure and short feed distances reduce pulsation and fiber bridging, while manual dumping into a mixer may produce localized overdosing. The loose bulk density of monofilament polypropylene microfiber is commonly reported in the range of 250–350 g/L; feed augers and screw conveyors should be calibrated against this range to avoid surging or underfeeding.
If clumping is observed during field batching, the dosage should not be increased to compensate. The addition sequence should be revised, or the dry-mix duration should be extended. Published rheological data for overdosing 12 mm monofilament polypropylene fiber in low-water concrete is limited. The operational upper boundary for this fiber geometry is generally considered to be 1.8 kg/m³; above this level, finishability, pump line pressure, and mixing uniformity may deteriorate. Plant-scale batch logs from forced-action pan mixers show that progressive addition of fiber over the aggregate stream is more effective than single-shot addition for maintaining distribution.
Addition of 0.9 kg/m³ of 12 mm monofilament polypropylene fiber modifies fresh concrete rheology by increasing yield stress and reducing slump. Batch data from forced-action pan mixers have shown slump reductions of 5–15 mm measured by EN 12350-2, although published data specific to this fiber configuration remains limited. For low-slump concrete placed by slipforming or roller compaction, dosages above 1.2 kg/m³ may require adjustment of aggregate grading or an increase in high-range water reducer dosage. In self-consolidating concrete, slump flow measured by EN 12350-8 can decrease by 50–100 mm at a dosage of 1.0 kg/m³, depending on paste volume, aggregate shape, and admixture type.
The crack-control mechanism of the microfiber is physical interception of plastic shrinkage crack propagation. In restrained slab tests conducted under ASTM C1579-21, synthetic microfiber dosages of 0.9 kg/m³ have been reported to reduce crack area by 50–80% compared with unreinforced control concrete. The response of 12 mm monofilament geometry is governed by bleed rate, evaporation rate, surface finishing timing, and curing regime. The fiber does not mitigate thermal cracking or structural load-induced cracking in the same manner as steel fibers or macro-synthetic fibers.
For post-crack residual strength, macro-synthetic or steel fibers are specified under EN 14651 or ASTM C1609/C1609M. The product does not replace air entrainment for freeze-thaw resistance under ASTM C666/C666M. At addition rates above 1.5 kg/m³, laboratory confirmation of pumpability, finishability, and hardened air-void properties is necessary. The product should not be used as a primary corrosion-control measure in reinforced concrete; cover depth, concrete quality, and crack-width limitations remain governed by Eurocode 2 or ACI 318 requirements.
In applications where shrinkage crack control and corrosion resistance are compared, the 12 mm monofilament polypropylene fiber is positioned between fibrillated microfibers and macro-synthetic structural fibers. The comparative matrix in Table 1 includes typical ranges obtained from producer data sheets and standard test methods.
| Property | Monofilament PP fiber, 12 mm | Fibrillated PP fiber, 12 mm | Steel hooked-end fiber, 30 mm | Alkali-resistant glass fiber, 12 mm |
|---|---|---|---|---|
| Density (g/cm³) | 0.91 | 0.91 | 7.85 | 2.68 |
| Tensile strength (MPa) | 300–500 | 300–450 | 800–1500 | 1000–1700 |
| Elastic modulus (GPa) | 3–5 | 3–5 | 200 | 70 |
| Typical dosage (kg/m³) | 0.6–1.5 | 0.6–1.2 | 15–40 | 1–3 |
| Primary crack-control function | Plastic shrinkage microcrack interception | Plastic shrinkage microcrack interception | Post-crack structural bridging | Early-age crack control; brittle failure if overdosed |
| Corrosion behavior in concrete | Inert; unaffected by cement alkalis | Inert; unaffected by cement alkalis | Requires concrete passivation; corrosion risk at cracks | Alkali-resistant; no electrochemical corrosion |
The principal difference between monofilament and fibrillated polypropylene fiber is geometric. Monofilament fiber is extruded as individual round filaments and cut to discrete 12 mm lengths. Fibrillated polypropylene fiber is a slit-film product that opens into a net-like structure during mixing. Monofilament geometry provides a higher number of individual filaments per kilogram at equivalent length because of the controlled circular cross-section, but it also exhibits stronger electrostatic interaction and may require more careful addition sequencing in dry conditions. Steel fibers provide significantly higher elastic modulus and are used for structural post-crack performance, but they increase density and corrosion susceptibility. Alkali-resistant glass fiber provides high tensile strength and modulus but can produce rough surface finish and requires alkali-resistant chemistry to avoid long-term degradation.
High-performance concrete containing silica fume at 5–10% by mass of cement and polycarboxylate ether high-range water reducer has reduced free water and a paste-rich matrix. Addition of 12 mm monofilament polypropylene fiber to such mixtures increases plastic viscosity and may reduce slump flow more than in conventional concrete at the same dose. The batching sequence should place the fiber with aggregates and dry-mix for 30–60 s before adding cement, silica fume, water, and high-range water reducer. This sequencing prevents fiber clumping in low-water paste and allows aggregate motion to separate the filaments, with subsequent wet mixing for 4–5 min at the mixer manufacturer’s rated speed.
Polypropylene microfiber does not participate in cement hydration reactions and shows no significant chemical incompatibility with silica fume or polycarboxylate ether admixtures. Published isothermal calorimetry data specific to 12 mm monofilament polypropylene fiber in silica-fume concrete is limited, but the polymer is hydrophobic and inert. The dominant effect is physical: the fiber increases the solid surface area in the paste and can reduce available free water at the aggregate-paste interface. In self-consolidating mixtures, the dosage should be limited to 0.9–1.2 kg/m³ unless full-scale pump and formwork trials are performed. Field measurements of slump flow by EN 12350-8 and viscosity class by EN 12350-9 should be used to verify placement performance.
Storage of polypropylene fiber before use requires protection from ultraviolet exposure. Prolonged direct sunlight can degrade the polymer surface and reduce tensile performance. Storage in closed, dry warehouses at ambient temperatures below 40 °C is acceptable. If packaging has been exposed to moisture or condensation, the fiber should be dried in a forced-air hopper at a maximum temperature of 40 °C before charging. The product should not be used in matrices exposed for extended periods to service temperatures above 150 °C, because polypropylene softens and loses mechanical integrity.
Batch release documentation for MICROFIBER - Monofilament Polypropylene Fiber, 12 mm should record fiber length distribution, diameter, tensile strength, and packaging moisture content according to EN 14889-2:2006 factory production control requirements. Table 2 lists relevant compliance anchors.
| Standard or regulation | Relevance | Application |
|---|---|---|
| EN 14889-2:2006 | Polymer fibers for concrete: definitions, specifications, and conformity | CE marking and factory production control |
| ASTM C1116/C1116M-23 | Standard specification for fiber-reinforced concrete and shotcrete | Type III synthetic fiber designation |
| ASTM C1579-21 | Evaluating plastic shrinkage cracking of restrained fiber-reinforced concrete | Performance comparison for plastic crack control |
| ISO 9001:2015 | Quality management systems | Batch traceability and production control |
| Regulation (EC) No 1907/2006 REACH | Registration, evaluation, authorisation, and restriction of chemicals | Polymer exemption assessment for EU use |
The product should not be used as a substitute for structural reinforcement and does not alter required cover depth, joint spacing, curing regime, or structural design under ACI 302.1R-15 or EN 13670. The fiber does not compensate for poor curing or deficient mix design. In concrete with high evaporation rates exceeding 1.0 kg/m²/h, supplementary measures such as fogging, windbreaks, or evaporation reducers remain necessary because plastic shrinkage cracking is driven primarily by surface moisture loss. The addition of 0.9 kg/m³ microfiber reduces crack width and total crack area under controlled testing, but does not eliminate the need for early-age curing.
