For slab-on-ground concrete placements where early-age moisture loss through exposed surface area exceeds 0.5 kg/m²/h and welded wire mesh is either omitted or positioned below the top third of the slab, MasterFiber F 018 – polypropylene fibrillated microfiber – is dosed at 0.9 kg/m³ to 1.8 kg/m³. The governing specification is ASTM C1116/C1116M Type III synthetic fiber-reinforced concrete, with slab construction practice following ACI 302.1R-15. The fiber functions by reducing capillary pressure build-up during the plastic phase; its fibrillated structure increases specific surface area relative to monofilament polypropylene, which modifies the film rupture threshold at the meniscus. EU regulatory alignment is established through the polymer exemption under REACH Article 2(9), while the Safety Data Sheet is maintained under EC No 1907/2006, Article 31. The dosage is not linearly transferable from monofilament fiber: at 0.9 kg/m³, the number of individual fibrillated elements per cubic metre is higher than at the same mass of a smooth monofilament because of splitting, but field-batched concrete with coarse aggregate above 20 mm can exhibit localised fibre entrapment if the fiber is added into an empty truck mixer before aggregates are charged. Production-scale batching therefore uses automated dispensers that introduce the fiber at the aggregate transfer belt after the first quarter of coarse aggregate has entered the mixer. Drum speed is held at 14–18 rpm for a minimum of 4–5 min after fiber addition; shorter mixing times are associated with agglomerate retention behind the blades. In central mix plants using a twin-shaft compulsory mixer with a discharge capacity of 1.0–2.0 m³, the fiber is introduced through a pneumatic lance after the first half of the sand and coarse aggregate has entered, and the wet mixing cycle is extended by 15–20 s beyond the baseline. Terminal product types include industrial floor slabs, external hardstandings, machine foundation slabs, and access pavements where the fiber is specified for plastic shrinkage crack control rather than structural load capacity. The boundary condition is explicit: MasterFiber F 018 does not replace bottom or top steel reinforcement in slabs requiring load transfer at construction joints or control joint armouring, and published data for long-term flexural performance of this specific fibrillated product in suspended structural slabs is limited.

Precast Secondary Reinforcement Without Mesh: Shrinkage Control in Thin-Wall Sections

When the addition rate is set at 0.6–1.2 kg/m³ in a counter-current pan mixer processing 500 L batches of zero-slump concrete for thin-wall precast elements, MasterFiber F 018 disperses as discrete fibrillated tapes rather than as bundled strands if it is added to the dry aggregate before water. The governing compliance framework is EN 14889-2:2006 for polymer fibres in concrete, supplemented by EN 13369:2018 for common precast concrete rules; conformity documentation includes the fiber manufacturer’s declaration and the precast producer’s internal factory production control. The production process is constrained by the vibration compaction stage: external formwork vibrators operating above 50 Hz can drive lower-density polypropylene toward the surface, producing visible fibre-rich areas on demoulded faces. Plant procedures therefore limit high-frequency vibration to 20–40 s per mould and sequence vibration only after the fibre-bearing concrete has filled the entire section. At 0.6 kg/m³ the fibre volume fraction is below 0.07%, while at 1.2 kg/m³ it approaches 0.13% by volume. In precast concrete with a water-cement ratio below 0.40, the higher dosage is selected only if an extended mixing time of 60–90 s is available, because low free water delays the opening of the fibrillated tapes. The fibre addition point is preferentially after sand and cement but before the final water fraction, allowing the mechanical shear of the dry aggregates to separate the tapes before full wetting. Typical terminal product types are manhole rings, cable troughs, curb units, inspection chamber bases, and other non-prestressed elements where secondary mesh is difficult to position. MasterFiber F 018 is specified only for early-age shrinkage control in this route; it is not a substitute for reinforcement required by the structural design of manholes under EN 1917 or by point-load tests in EN 124 for gully tops. Published data for long-term crack-width behaviour under repeated vehicular loading in specific thin-wall geometries remains limited; precast plants usually confirm fibre contribution through comparative shrinkage panel trials before series production.

Mechanically induced shear during dry-mix plaster manufacture is sufficient to open fibrillated polypropylene tape only if the addition point precedes the first 50% of the dry mixing cycle. In formulations compliant with EN 998-1:2016 for rendering and plastering mortar and EN 1504-3 for repair mortars, MasterFiber F 018 is incorporated at 0.05–0.15% by total dry batch mass, equivalent to 0.5–1.5 kg per tonne of dry blend. The preferred equipment is a horizontal plowshare mixer with a working volume of 100–1000 L and tip speed between 5 m/s and 10 m/s; a dry-blending time of 90–120 s before the first water spray is necessary to prevent fibre clumps from surviving into the wet mortar. In pneumatic conveying systems, the fibrillated structure exhibits electrostatic separation at line velocities above 25 m/s, and plants that transfer the dry blend to packaging or silo filling should use grounded piping and avoid long-radius bends that stratify the light fibre fraction. Terminal finished products include cement-based basecoats, spray-applied renders, one-component repair mortars, and facade patching compounds. The operational boundary is viscosity-related: when the dosage exceeds 0.15% by dry mass, wet mortar viscosity measured by a rotational viscometer at 20 rpm may rise sufficiently to reduce sprayability in airless spray equipment, and the plowshare mixer motor current can increase by 5–10% during the wet cycle. Published data for this specific product in mixed binder systems containing limestone filler, redispersible polymer powder, and cellulose ether is limited; plant trials with the actual formulation are required to set the upper dosage.

What Limits Pumpability When Wet-Mix Shotcrete Is Dosed Above 1.5 kg/m³ of Fibrillated Polypropylene?

The limiting factor is not the fibre melting point or the cement alkalinity; it is the increase in apparent viscosity and the mechanical entanglement of fibrillated tapes at transitions in the delivery line. In wet-mix sprayed concrete conforming to EN 14487-1:2005 and EFNARC 1999, MasterFiber F 018 is batched at 1.0–1.5 kg/m³ of concrete. The fiber is introduced at the batching plant, not at the nozzle, and is added after the sand but before the cement and remaining water in a twin-shaft compulsory mixer with 60–90 s forced mixing. Delivery is normally by an S-valve positive-displacement piston pump with a 50 mm or 65 mm internal diameter hose; at 1.0 kg/m³ the effect on line pressure is typically lost within normal pump stroke fluctuation, but at 1.5 kg/m³ bends of 45° or more and reductions at the nozzle can become retention zones. Field measurements on wet-mix lines show that a dosage above 1.5 kg/m³ can increase pumping pressure by 10–20% under the same slump-flow class, but published data for this specific fibrillated geometry in high-velocity wet shotcrete is limited. The operational compromise is a slump between 140 mm and 200 mm measured by EN 12350-2 and air content below 4% to prevent the fiber from attaching to entrained air bubbles and rising to the surface. Terminal products include temporary tunnel linings, slope stabilization shells, rockfall protection layers, and canal repair linings. The fiber is not a substitute for structural steel mesh or rock bolts in permanent shotcrete structures; for permanent linings, the design must be based on reinforcement according to EN 1992-1-1 or project-specific rock support classification.

In dry-mix sprayed concrete, the addition ratio is placed in the pre-blended dry material at 0.9–1.8 kg/m³; however, the risk of fibre balls at the water ring is higher because wetting time is only a few seconds. Published data for this configuration is limited to equipment-specific trials. The preferred equipment is a rotor machine with a 25 mm or 38 mm water ring nozzle, and the fiber must be free of static clumps before the material enters the rotor. Because the fiber is hydrophobic, the water pressure at the nozzle must be at least 0.4 MPa to wet the fibrillated surface before impingement onto the substrate.

Cementitious screed batches prepared at a water-cement ratio of 0.45–0.55 receive MasterFiber F 018 at 0.5–1.2 kg/m³ for plastic shrinkage crack reduction in bonded, floating, and heated floor screeds. The governing standard is EN 13813:2002 for screed material and floor screeds, and binder conformity is tested according to EN 13454-2. In a forced-action mobile screed mixer with a batch capacity of 200–400 L, the fiber is added to the aggregate hopper before the cement; the mixing time after water addition is held between 90 s and 120 s because longer mixing with a horizontal shaft can tear the fibrillated tape into finer elements that reduce the visible crack-bridging effect without improving workability. For pumpable screeds, passage through a piston pump with a 25–35 mm diameter hose and up to 50 m of line is possible at the upper bound of the dosage if the slump is maintained above 210 mm; however, bends should be minimised because the fibrillated fiber, unlike monofilament, can accumulate at hose couplings where the internal diameter is reduced. Terminal product types include bonded screeds, unbonded screeds on membranes, floating floor screeds over insulation, and heated screeds with embedded pipes. The operational boundary is that MasterFiber F 018 does not confer flexural strength required for structural screeds; load-bearing screed categories under EN 13813 must still be designed with the declared flexural strength of the cementitious binder and, where applicable, steel reinforcement. Published data for the effect of this specific fibrillated microfiber on the thermal conductivity of heated screeds is limited; the dosage is kept at the lower end when floor heating response time is a project requirement.

When Continuous Pin Mixers Discharge Gypsum Stucco Slurry at 15 m/min, Fibre Dispersion Depends on Addition Point

Continuous gypsum board lines running at belt speeds above 15 m/min impose a slurry residence time of 5–10 s in the pin mixer. Under these conditions, MasterFiber F 018 at 0.10–0.25% by weight of calcined stucco must be added with the dry stucco stream at the inlet, not into the water or foam stream, because the hydrophobic fibrillated surface cannot be wetted fast enough if the slurry is already formed. Compliance for board products is governed by ASTM C1396/C1396M and EN 520:2004+A1:2009; the relevant board test methodology is ASTM C473 for gypsum board and gypsum panel products. The fiber contributes to early-age drying shrinkage control between the forming station and the dryer inlet, where surface moisture loss is highest before the board achieves its stiffening point. The process constraint is the foam fraction: if the foam volume added to control board density is above the formulation limit, the reduced slurry viscosity can cause the fibrillated fiber to float and create surface discontinuities at the forming bar. Terminal products include standard gypsum wallboard, moisture-resistant board with hydrophobic additives, and gypsum ceiling tiles. The drying stage is not used to melt the polymer; the polypropylene component has a melting point near 160 °C, which is below the dryer air temperature, but the fiber remains embedded in the partially hydrated gypsum matrix and does not form continuous pores at this dosage. Published data for this specific fibrillated microfiber in high-speed gypsum board manufacture is limited; mill trials with stucco from the specific gypsum source are required because soluble anhydrite and hemihydrate ratio changes alter the dispersion window.