| HS Code | 748676 |
| Material | Polypropylene |
| Producttype | Staple fiber |
| Nominallength | 6-50 mm |
| Equivalentdiameter | 15-50 µm |
| Density | 0.90-0.91 g/cm³ |
| Meltingpoint | 160-170 °C |
| Tensilestrength | 300-700 MPa |
| Elongationatbreak | 15-30% |
| Elasticmodulus | 3-5 GPa |
| Acidalkaliresistance | Good to excellent |
| Waterabsorption | <0.1% |
| Thermalconductivity | 0.12 W/m·K |
| Electricalconductivity | Low / insulating |
| Flameretardancy | Combustible unless flame-retardant modified |
| Uvresistance | Limited unless UV-stabilized |
| Dispersion | Good in cementitious and construction mixtures |
| Typicaldosage | 0.6-1.8 kg/m³ concrete or 0.05-0.2% by volume |
| Color | Natural white, black, or custom |
As an accredited PP Staple Fiber for Building & Construction Materials factory, we enforce strict quality protocols—every batch undergoes rigorous testing to ensure consistent efficacy and safety standards.
| Packing | PP staple fiber packed in 20 kg woven bags, stacked on pallets, or 500 kg jumbo bags for building materials. |
| Container Loading (20′ FCL) | Container Loading (20′ FCL): PP Staple Fiber for Building & Construction Materials, palletized, moisture-protected, and securely stowed for export shipment. |
| Shipping | PP staple fiber for building and construction materials is packed in compressed bales or woven bags, palletized and shrink-wrapped. It is non-hazardous, shipped by truck, rail, or sea in dry, ventilated containers. Store away from moisture, direct sunlight, and ignition sources; avoid excessive stacking. |
| Storage | Store PP staple fiber for building and construction materials in a cool, dry, well-ventilated warehouse, protected from direct sunlight, rain, moisture, heat, flames, and ignition sources. Keep original packaging sealed and palletized off the floor. Avoid compression, sharp objects, oils, acids, alkalis, and dust. Maintain stable temperature and humidity, follow FIFO, and provide appropriate fire protection. |
| Shelf Life | Shelf life is typically 12–24 months in original sealed packaging, stored dry, cool, and away from direct sunlight and moisture. |
In slab-on-grade and jointless industrial flooring, polypropylene staple fibre with a cut length of 6–19 mm and linear density of 3–9 dtex is metered into the aggregate weigh hopper before cementitious binders and mix water are introduced. Compliance is generally assessed under ASTM C1116/C1116M-23 Type III synthetic fibre, EN 14889-2:2006 Class Ia microfibre, and slab execution documents such as ACI 302.1R-15; these standards set tolerances for fibre geometry, tensile strength, and alkali resistance rather than assigning structural post-crack capacity to micro-synthetic staple fibre. The common batching ratio for plastic shrinkage crack control is 0.6–0.9 kg/m³; some floor specifications require 1.2 kg/m³ under high evapouration conditions, but this raises fresh concrete viscosity and extends discharge time by 45–90 s in a 1.5–2.0 m³ planetary counter-current mixer. Production records indicate balling when fibre is added after 80% of mix water or when mixer blades have wear exceeding 8–10 mm; therefore the addition sequence places fibre between coarse aggregate and one-third of the water, with total mixing held at 4–6 min before pump discharge. Downstream finishing uses low-speed rotary equipment and prohibits early power trowel operation at plastic bleed surfaces; excessive steel trowel angle can expose melted or abraded fibre ends, producing surface fuzz that is corrected only by grinding. Finished product types include warehouse floor slabs, distribution centre aisles, light industrial pavements, residential slabs-on-grade, and non-structural hardscape toppings; the fibre functions primarily as plastic shrinkage micro-crack control and is not a substitute for load-transfer reinforcement or joint design.
The fibre has no post-crack structural role at these loadings; if residual flexural toughness is specified, macro-synthetic fibre conforming to EN 14889-2:2006 Class Ib or tested under ASTM C1609/C1609M-19a must be used at 3.0–6.0 kg/m³. Use of polypropylene staple fibre in polished concrete may be limited because surface grinding at 0–3 mm cut depth exposes fibre cross-sections; trial placement is required before full-scale application.
Dry-mix mortar plants incorporate polypropylene staple fibre at 0.5–1.5 kg per tonne of finished powder, equivalent to 0.05–0.15 wt%, depending on whether the end product is a C2 cementitious tile adhesive, an ETICS base coat, or a repair mortar. Industry conformity is demonstrated against EN 12004:2017 for cementitious tile adhesives, EAD 040083-00-0404 for external thermal insulation composite systems, and EN 998-1:2016 for rendering and plastering mortar; the fibre itself is generally required to satisfy EN 14889-2:2006 tensile strength and geometry clauses. Batching is executed in a horizontal ribbon mixer with a high-speed chopper at 20–30 m/s tip speed; the fibre is added after the filler and cement have been dry-blended for 90–120 s, then the mixer is run for another 120–180 s to disperse fibre bundles without melting. Residual moisture in the dry mix must remain below 0.2% before packaging, because polypropylene staple fibre absorbs negligible water but can carry electrostatic charge at low relative humidity; plants in regions with RH below 30% often fit ionising bars on weigh belts to prevent fibre clumps from entering the ribbon mixer. The wet-side process at the applicator level involves mixing the powder with 24–32% water by weight, slaking for 3–5 min, and re-mixing; in tile adhesive formulations the fibre contributes to plastic crack reduction and anti-slump behaviour rather than bond strength, so tensile adhesion measured by EN 1348:2007 should not be expected to increase linearly with fibre content. Finished product categories include C1/C2 and S1/S2 deformable tile adhesives, ETICS basecoats and smoothing renders, thin-bed repair mortars, and cement-based self-leveling screeds; in deep-pour self-leveling applications the fibre loading is kept at the lower end because higher loadings can increase viscosity and reduce flow table spread measured by EN 1015-3:1999.
In wet-mix sprayed concrete for tunnel lining and slope stabilisation, polypropylene staple fibre is added at 1.2–2.0 kg/m³ when the primary objective is fresh-state crack control, and at 2.0–3.0 kg/m³ when the specification requires improved fire spalling resistance under RWS or HC heating curves. The governing standards are EN 14487-1:2005 for sprayed concrete, ASTM C1436/C1436M-17 for shotcrete materials, and EN 14889-2:2006 for polymer fibre conformity; project-specific fire spalling tests are often conducted according to EN 1363-1:2012 with specimen conditioning to the relevant moisture state. Production-scale wet-mix lines show that the addition of PP staple fibre at 2.0 kg/m³ raises pumping pressure in a DN 80–DN 100 delivery line by 0.8–1.5 MPa compared with plain shotcrete, depending on line length and vertical lift; the effect is more pronounced when fibre bundles remain in the mix because of insufficient agitating speed in the truck mixer. The fibre is introduced at the batching plant into a truck mixer operating at 8–12 rpm, with mixing time extended by 3–5 min; at the nozzle, compressed air at 0.6–0.8 MPa atomises the mix, and alkali-free accelerator is dosed at 4–8% by cement weight.
The fire-spalling mechanism in tunnel linings depends on fibre melting and thermal decomposition at 160–170°C, which creates percolation channels for vapour pressure release; therefore fibre distribution must be uniform, because local fibre-poor zones may spall under rapid heating. Terminal applications include permanent tunnel linings, temporary rock support, slope facing, swimming pool shells, and repair of deteriorated concrete; the PP staple microfibre is not expected to replace steel fibre or macro-synthetic fibre for flexural ductility, so when toughness class E 1000 or higher is specified, the micro staple fibre is used only as a secondary additive.
Gypsum plasterboard and hand-applied gypsum plaster formulations use polypropylene staple fibre cut to 6–12 mm at 0.10–0.25% by gypsum weight, equivalent to approximately 0.10–0.25 kg per 100 kg of calcined gypsum. Published data for this specific configuration is limited compared with cementitious systems; conformity is therefore verified under ASTM C1396/C1396M-17 for gypsum board and EN 13279-1:2008 for gypsum binders and gypsum plasters, while fibre geometry and defect level are checked by optical microscopy against the supplier’s certified values. In continuous plasterboard lines, the fibre is dosed into a high-shear pin mixer after stucco and water have begun to form a slurry; rotor tip speeds in the pin mixer are typically 15–25 m/s, and the slurry is discharged onto the lower paper liner within 10–25 s of fibre addition to prevent fibre separation. The board then passes through forming plates and a drying tunnel at 70–100°C, which is below the 160–170°C melting range of polypropylene; fibre loss through thermal degradation is therefore low, but prolonged residence at the upper drying temperature can cause surface discolouration. Downstream product categories include standard gypsum wallboard, moisture-resistant board, gypsum base for office partitions, and bagged gypsum plaster; the staple fibre function is limited to crack reduction in the hardened gypsum matrix and green-strength handling, not to fire resistance or mechanical load capacity.
Vertical vibration and roller-compacted precast elements, including drainage pipes, manhole rings and box culverts, are produced with polypropylene staple fibre at 0.6–1.0 kg/m³ in the concrete mix. Compliance is assessed through EN 1916:2002 for concrete pipes and manholes, ASTM C76-22 for reinforced concrete culvert and storm drain pipe, and EN 14889-2:2006 for the fibre itself; the fibre is classified as a non-structural micro-synthetic additive and does not reduce the required steel reinforcement area. In dry-cast production, the fibre is added to the pan mixer after the aggregates and cement are combined, with mixing time of 3–5 min and moisture content controlled at 6–8%; the concrete is then compacted by external vibrators at 3,000–6,000 rpm and immediate demoulding is practised. Fibre balling is observed when the fibre is added to dry aggregate before cement, especially at cut lengths above 12 mm, so the sequence is reversed compared with wet-cast concrete. In wet-cast manhole production using slump mix of 40–80 mm, the fibre reduces plastic settlement cracking along reinforcement lines; however the vibration time must be shortened by 10–20% to prevent fibre orientation at the form face, which can leave visible fibre hairs after demoulding. Finished products include concrete pipes, manhole rings, catch basins, culvert units, and box culverts for stormwater and sewerage networks; these are generally cured by steam at 60–80°C, below the PP melting range, so fibre integrity is retained.
Nonwoven geotextiles for subgrade separation, drainage and erosion control are produced from polypropylene staple fibre of 6–15 denier and 38–90 mm cut length at a blend ratio up to 100 wt%; in some products, a proportion of coarser fibre is combined with finer fibre to achieve specified pore size distribution. Industry conformity is assessed under EN 13249:2016 for geotextiles used in roadways and other trafficked areas, ASTM D4632/D4632M for grab tensile load, and ASTM D4751 for apparent opening size; fibre supply is often certified against REACH and RoHS for heavy metal content. The fibre is opened, carded, cross-lapped and needle-punched into fabrics of 100–800 g/m², then wound into rolls; terminal products include separation geotextiles, drainage geotextiles and protection layers for geomembranes. Strength and opening size must be specified from site soil conditions, because the needle-punched product is not an intrinsic filter without site-specific permittivity data.
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Polypropylene staple fiber for building and construction materials is a short-cut synthetic fiber produced by extruding a virgin propylene homopolymer with a melt flow rate of 3–25 g/10 min at 230 °C / 2.16 kg in accordance with ISO 1133-1:2022. The extruded filaments are water-quenched, hot-stretched through a heated drawing zone to orient the polymer chains, annealed, and cut into discrete staples. The resulting product, designated PP-SF, is intended for secondary reinforcement of cementitious matrices, mortar, plaster, screed, grout, and non-structural precast concrete. It is not a replacement for primary reinforcing steel or for steel fiber where post-cracking residual flexural capacity is a design requirement. Typical solid-state density is 0.90–0.91 g/cm³ by ASTM D792-20. The fiber is hydrophobic and exhibits moisture regain below 0.1% by dry mass. Melting point is 160–170 °C, and the processing temperature must remain below 160 °C if the fiber is used in bituminous mixtures.
Model designations follow the convention PP-SF-[linear density]/[cut length]-[surface type]. Representative grades include PP-SF-3/6, a 3-denier (3.3 dtex) fiber cut to 6 mm for repair mortars and self-levelling grouts; PP-SF-3/12, a 3-denier fiber cut to 12 mm for floor screeds and renders; PP-SF-6/19, a 6-denier (6.7 dtex) fiber cut to 19 mm for cast-in-place concrete and slabs on grade; and PP-SF-6/24 or PP-SF-15/38 where longer embedment is specified, subject to mixer dispersion verification. Surface type E denotes embossed monofilament, C denotes crimped staple, and F denotes fibrillated tape. The denier-to-dtex conversion is 1 denier = 1.111 dtex. Assuming circular cross-section, the nominal filament diameter for 3 dpf is approximately 20–22 µm, for 6 dpf approximately 30–32 µm, and for 15 dpf approximately 48–50 µm.
In fresh concrete, the aqueous phase is a saturated Ca(OH)2 solution with pH typically above 12.5. Polypropylene is a paraffinic hydrocarbon and does not undergo hydrolysis or alkali attack in this environment. In contrast, polyester (PET) fiber is susceptible to alkaline hydrolysis at ester linkages; continuous wet-mix exposure at pH 12.5 can progressively reduce PET tenacity. E-glass fiber can lose strength in ordinary Portland cement unless supplied as alkali-resistant glass with suitable zirconia content and correct sizing. PP fiber also differs from glass fiber in handling behaviour: glass filaments are brittle and can fracture during high-shear mixing, while PP staple is ductile with elongation at break of 15–25% when tested by ASTM D3822/D3822M-14. The lower elastic modulus of PP, typically 3.5–5.5 GPa, compared with 72 GPa for AR-glass and 200 GPa for steel, means that PP fiber is effective for plastic shrinkage crack control but contributes limited post-cracking stiffness.
| Property | PP staple fiber | AR-glass fiber | Cold-drawn steel fiber | Polyester (PET) fiber |
|---|---|---|---|---|
| Density | 0.91 g/cm³ | 2.68 g/cm³ | 7.85 g/cm³ | 1.38 g/cm³ |
| Tensile strength | 350–550 MPa | 1700 MPa | 1000–2000 MPa | 500–800 MPa |
| Elastic modulus | 3.5–5.5 GPa | 72 GPa | 200 GPa | 10–15 GPa |
| Elongation at break | 15–25% | 2–4% | 3–10% | 15–30% |
| Behaviour in pH 12.5 Ca(OH)2 | alkali-inert | only AR-grade resists attack | no chemical attack but corrosion possible in chloride exposure | alkaline hydrolysis can reduce tenacity |
Compared with polyvinyl alcohol fiber, which is sometimes used in cementitious composites, PP staple has lower elastic modulus and lower fiber-matrix bond because of its hydrophobic surface. Mechanical anchoring is improved by embossed or crimped surface finishes. Polyvinyl alcohol fiber can provide higher modulus, generally in the range of 25–40 GPa, and stronger hydrogen bonding to cement hydrates, but it is typically higher cost and may require more careful dosing. PP fiber therefore serves a lower-cost crack-control function where post-cracking strength demand is low and where corrosion integrity, low density, and alkali resistance are priorities.
For cementitious applications, polymer fibers fall under EN 14889-2:2006 when placed on the European market. The manufacturer or distributor must declare fiber geometry, tensile strength, elastic modulus, and effect on concrete workability for each lot. In practice, lot-acceptance testing for the PP-SF line includes linear density according to ASTM D1577-07(2018), single-fiber tensile properties according to ASTM D3822/D3822M-14, fiber length by optical or sieve measurement, and melt flow rate of the parent resin according to ISO 1133-1:2022. Representative values for PP-SF-6/19 are a linear density of 6 dpf (6.7 dtex), cut length 19 mm, tenacity 4.0–5.5 cN/dtex, elongation 15–25%, and density 0.91 g/cm³. For PP-SF-3/6, the tenacity is 4.5–6.0 cN/dtex because of finer denier and higher draw ratio. The cut length should be verified against the supplier certificate; published universal tolerances are limited, but tight grading limits are required to avoid dosing stratification in pneumatic feeding systems.
Conformance to ASTM C1116/C1116M-10a may be specified for fiber-reinforced concrete. This standard classifies polymer fibers as Type III synthetic fiber. The specification covers tensile strength, alkali resistance, and geometry for concrete. Some purchasing authorities require alkali resistance screening by immersion in 1 N NaOH at 60 °C for 24 h with retained breaking force above 90%. For PP, exposure to saturated Ca(OH)2 at 60 °C for 28 days typically produces no significant mass loss or tensile loss. The product is not classified as hazardous under REACH and falls outside the restricted substance scope of RoHS Directive 2011/65/EU as a building material. Single-fiber tensile testing is performed at 20 mm gauge length and 10 mm/min crosshead speed using a 20 N load cell for deniers below 10 dpf; higher-denier products require a 50 N load cell to avoid range errors at break.
Cold-drawn steel fiber in marine splash zones or sulphate-exposed concrete can undergo corrosion, producing rust staining and potential spalling at exposed surfaces. In these exposure classes, polypropylene staple fiber is specified because it is electrochemically inert and does not participate in chloride-induced corrosion. It is also lighter: at a dosage of 0.9–1.8 kg/m³, the fiber volume fraction is below approximately 0.2%, compared with 15–60 kg/m³ for steel fiber. This makes PP staple useful for reducing plastic shrinkage cracks in slabs on grade, white-topping, and non-structural precast panels where corrosion-resistant secondary reinforcement is required. The fiber is added as a secondary reinforcing material; structural load-bearing capacity must be provided by continuous steel reinforcement or by accepted structural fiber designs. Published data for residual flexural strength of PP fiber concrete at dosage 1.8 kg/m³ are limited, and the lower modulus of PP should be expected to produce lower post-cracking residual capacity than steel fiber.
In chloride-exposed marine concrete, some specifications require compliance with EN 14889-2:2006 for polymer fibers and ASTM C1116/C1116M-10a Type III. PP fiber does not form galvanic cells with steel reinforcement and does not require passivation. However, PP fiber is not a corrosion inhibitor and should not be substituted for adequate cover, concrete quality, or supplementary cementitious materials. The low density and high specific surface area can influence fresh mix rheology. In shotcrete, cut lengths of 12–19 mm are preferred because longer staples may reduce pumpability and increase rebound. The same corrosion resistance applies to sulphate-bearing groundwater and external sulphate attack environments, but the fiber does not chemically mitigate sulphate attack on the paste matrix; sulfate-resisting cement or supplementary binders remain necessary for aggressive exposure classes.
Production-scale batching with a 1.5 m³ twin-shaft compulsory mixer shows that PP staple should be added after coarse aggregate and before water, or directly through a pneumatic dosing lance into the dry-mixed component. Fibers added after water can form clumps at the mixer walls and paddle shafts. For dosages above 1.2 kg/m³, pre-weighed water-soluble bags or automated loss-in-weight feeders are used to reduce balling. In a 2.0 m³ pan mixer running at 28 rpm, a dispersing time of 45–60 s after addition is typical for 19 mm cut staple. Longer fiber such as 24 mm or 38 mm may require reduced feed rate and extended mixing by 10–20 s to prevent clumping around paddles. Published data for the exact relation between mixer shear and fiber bundle size are limited.
Fresh concrete testing at 0.9 kg/m³ of PP-SF-6/19 in a 20 mm maximum-size aggregate mix often shows a slump reduction of 10–30 mm when measured by ASTM C143/C143M-20. Air content measured by ASTM C231/C231M-17a may shift by 0.5–1.0%, requiring adjustment of air-entraining admixture dosage. Fiber addition does not eliminate plastic shrinkage cracking but reduces total crack area and average crack width in restrained plastic shrinkage testing. The effect is dose-dependent: at 0.6 kg/m³, crack area reduction is smaller than at 1.2 kg/m³. At dosages above 2.0 kg/m³, the mix may require high-range water reducer to restore workability, and pump pressure should be monitored because fiber-laden concrete can produce line pressure increases of 0.5–1.5 bar in 100 mm nominal bore delivery lines depending on mix design. Fine-denier fibers have a higher total surface area at equal mass; 3-denier fiber has approximately twice the surface area of 6-denier fiber, which increases water demand and aggregate void interaction.
Storage conditions affect dosing repeatability. The fiber is hydrophobic, but surface condensation at relative humidity above 60% can cause fiber bridging in screw feeders. Store in dry, covered storage and avoid direct ultraviolet exposure for more than 6 months unless a UV-stabilized grade is specified. The product is not intended for use as primary flexural or structural reinforcement, and it is not recommended for hot-mix asphalt processed above 160 °C because of melt onset. It is also incompatible with strong oxidizing acids, hot aromatic solvents, and open-flame exposure. Contact with amine-based concrete admixtures does not create the same premature-crosslinking risk observed with some polymer latex systems, but admixture compatibility testing at the specified fiber dosage is required for high-range water reducer combinations.
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