For ground-supported industrial floor slabs, SikaFiber P/P 12 mm is incorporated at 0.9 kg/m³ to 1.2 kg/m³ to control early-age plastic shrinkage cracking during the first 6–12 h after screeding. In ready-mix operations, the preferred introduction point is the aggregate conveyor stream at the batch plant, ahead of the mixer. Direct addition into the truck drum after water can result in monofilament balling when drum speed is below 14 rpm or when slump exceeds 150 mm. Central mixer or truck mixer high-speed mixing for a minimum of 5 min at 18–22 rpm is required to separate the bundled monofilaments and distribute them uniformly through the mix. The fibre is covered by EN 14889-2:2006 for CE marking; the hardened concrete falls under ASTM C1116/C1116M-10a Type III synthetic fibre-reinforced concrete when specified. Plastic shrinkage crack evaluation may be performed according to ASTM C1579-21, which provides a restrained slab cracking test method. The terminal elements include logistics apron slabs, warehouse floors, and internal machine foundation slabs where the acceptance criteria focus on early-age crack count reduction, not structural load capacity. Because the fibre does not replace structural steel, the slab bending capacity is governed by the same design standards as unreinforced concrete. Published data for this specific product configuration is limited in relation to increased joint spacing above 4.5 m without designer verification.

Field finishing of fibre-dosed slabs introduces a specific interaction with ride-on power trowels. At addition rates above 1.2 kg/m³, visible surface fuzz may appear if the trowel blade angle is kept flat after the final bleed-water sheen disappears. This is a production-scale observation, not a laboratory failure mode, and it is managed by sequencing trowel passes with steel blades only after surface moisture has cleared. The fibre does not interfere with saw-cut timing when cuts are made within 24 h of initial set.

What Changes in Demoulding Crack Patterns for Precast Cable Ducts and Roadside Drainage Units?

Precast cable duct and roadside drainage units are demoulded after 16–24 h when the concrete compressive strength reaches 12–15 MPa; this is the period when corner and edge chipping is most common. The addition of SikaFiber P/P 12 mm at 0.6 kg/m³ to 1.0 kg/m³ reduces brittle edge fractures during demoulding and transport without altering the cover depth to steel reinforcement. In pan mixers or twin-shaft compulsory mixers, the fibre is dry-blended with sand and cement for 30 s before water is added, followed by a wet mixing cycle of 120 s. The dry-blend sequence is more important in precast than in ready-mix slab work because the lower water-to-cement ratio of 0.42–0.48 in precast mixes offers less free water for fibre dispersion. The moulds are filled on vibration tables at 40–60 Hz; over-vibration above 60 Hz can segregate the monofilament fibres toward upper corners. CE-marked precast elements are covered by EN 13369:2018 in combination with the relevant product standard, while the fibre itself carries EN 14889-2:2006. The fibre is not a substitute for lifting anchors or steel reinforcement in precast sections subject to high torsional handling loads. Terminal products include telecommunication cable ducts, roadside kerb drainage channels, and valve chambers where early-age edge integrity determines acceptance upon demoulding and unloading at the construction site.

When Wet-Mix Shotcrete Pump Pressure Limits Synthetic Fibre Addition

In wet-mix shotcrete placement, SikaFiber P/P 12 mm is introduced at 1.0 kg/m³ to 2.0 kg/m³ into truck mixer concrete before transfer to a swing-tube concrete pump. The primary process constraint is not slump loss but pump pressure stability. At 2.0 kg/m³, monofilament fibres can increase pumping pressure by 5–10% in small-diameter delivery lines with 50 mm inner diameter and long horizontal runs above 60 m. Published data for this specific configuration is limited; mix-specific calibration at the nozzle before permanent lining application is required. Sprayed concrete is specified under EN 14487-1:2005 and material testing may follow ASTM C1436-13. The fibre contributes to plastic shrinkage crack reduction in temporary slope protection and initial tunnel linings but, because it is a microsynthetic fibre, it does not provide the post-crack residual flexural strength of steel or macrosynthetic fibres. Rebound reduction is frequently cited in technical literature, but the measured reduction varies with nozzle angle of 70–90° to the substrate, nozzle distance of 1.0–1.5 m, and accelerator dosage. A single rebound percentage is therefore not technically valid without referencing a specific mix. Terminal components include temporary excavation support linings, rock slope scaling barriers, and fire-protection linings where early-age plastic cracking control is the acceptance requirement.

When anhydrite or cement-based screeds are laid above underfloor heating circuits, the fibre is dry-mixed with the binder and sand before water is added at 0.6 kg/m³ to 0.9 kg/m³. This application is governed by EN 13813:2002 for screed materials and performance classifications. In continuous mixer-pump systems, the monofilament is metered into the dry mix through a vibratory feeder before the mixing chamber; adding it to the pump hopper after wetting causes fibre lumps that block 25 mm and 35 mm rotor-stator pump outlets. The terminal screed thickness over heating pipes is normally 35–45 mm for proprietary systems, but the fibre does not alter the minimum cover required by the pipe manufacturer. Early-age crack control in heated screed panels is addressed by the fibre at the plastic stage, not by thermal expansion resistance after commissioning. The hardened screed must still be commissioned under the heating system protocol with a gradual temperature rise rate, commonly 5°C/day. Bonded, unbonded, and floating screed configurations each accept the fibre, provided the mixing sequence is dry-blend first. Terminal products include residential underfloor heating bases, commercial floor toppings, and renovation screeds over old concrete slabs where edge curling and plastic cracking are primary failure modes.

Which Marine Exposure Conditions Justify Polypropylene Fibre in Mass Concrete?

Marine splash-zone concrete is specified under EN 206:2013+A2:2021 exposure class XS3, where chloride penetration and tidal wet-dry cycling govern durability. SikaFiber P/P 12 mm is added at 0.9 kg/m³ in such exposures for early-age crack reduction, not as a substitute for low water-to-binder ratio or supplementary cementitious materials. The fibre is mixed in the same plant addition sequence as slab concrete: aggregate stream, binder, fibre, then water and plasticizer. Field placement of mass concrete in marine works uses tremie pipes or pump booms; the fibre does not alter pumpability at this dosage. Hardened concrete testing includes chloride migration per EN 12390-18:2021 and compressive strength per EN 12390-3:2019. The operational boundary is explicit: polypropylene fibre does not prevent corrosion of embedded steel reinforcement in cracked marine concrete, and crack width limits under EN 1992-1-1 remain the governing design criterion. Published data for polypropylene fibre effect on salt scaling in this specific product configuration is limited. Terminal components include harbour wave walls, outfall structures, and quay wall capping beams where plastic shrinkage reduction during large-area casting is the sole fibre-related acceptance parameter.

During precast retaining wall panel handling, edge spalling is most commonly recorded when demoulding occurs at low early-age strength or when forklift forks bear directly on unprotected top edges. The fibre is dosed at 0.6 kg/m³ to 1.0 kg/m³ in self-compacting or stiff precast mixes, and it is added to the pan mixer before the coarse aggregate, not after plasticizer. In this sequence, the monofilament disperses through the mortar fraction and reduces edge breakage during stripping, rotation, and yard stacking. The precast elements are produced under EN 13369:2018 and the fibre under EN 14889-2:2006. Compressive strength acceptance at demoulding is typically 15 MPa for structural retaining units, measured by rebound hammer correlation or cube compression per EN 12390-3:2019. The fibre does not alter the structural reinforcement cage design in cantilever retaining walls, and lifting anchor capacity is governed by the anchor supplier and embedment depth. Terminal products include interlocking retaining wall blocks, gravity retaining panels, and acoustic barrier side panels where transport and installation damage are primary non-structural failure modes.

Cementitious Repair Mortars and the Effect of Fibre Dispersion on Bond Strength

Repair mortar batching with 12 mm monofilament polypropylene fibre at 0.5 kg/m³ to 0.9 kg/m³ is executed in a forced-action mixer with a dry blending step of 60 s before water and polymer dispersion are introduced. The fibre must be dispersed before the polymer dispersion is added because polymer particles can agglomerate around undispersed fibre bundles, creating weak inclusions that lower pull-off strength. Repair mortars for structural concrete are specified under EN 1504-3:2005, with bond strength acceptance tested by EN 1542. At addition rates above 0.9 kg/m³, some patch mixes exhibit reduced flow in trowel-applied repairs, and the operative limit is verified by flow table spread of 180 ± 10 mm for Class R3 or R4 repair mortars. The fibre does not substitute for corrosion inhibitors in chloride-exposed patch repairs, nor does it replace the required surface preparation roughness or substrate saturation condition. Terminal components include hand-applied patch repairs on reinforced concrete beams, edge reconstitution of deteriorated columns, and low-shrinkage repair fills in car park slabs, where early-age plastic shrinkage cracking in the fresh patch is the main defect to be controlled.