Adfil Strux 85/50 is incorporated into ready-mixed concrete for jointless ground-supported slabs in logistics hubs, automated storage and retrieval warehouses, and container terminals. The PP/PE macro-fibre is dosed at 1.8 kg/m³ to 4.5 kg/m³; the lower bound is applied to slabs with saw-cut contraction joints, while the upper bound is specified where joint spacing exceeds 50 m and early-age shrinkage cracking is to be controlled without welded-wire mesh. In a twin-shaft compulsory mixer with a rated batch volume of 3 m³, the fibres are introduced after aggregate-cement homogenisation and before admixture dosing stabilises the water-cement ratio at 0.42 to 0.48. On placement, a laser-guided screed strikes off the concrete at a slump of 120 mm to 160 mm, and fibre clumping in the screed auger is managed by keeping the discharge gate clear and rejecting partially opened bags at the batching plant. The hardened slab is evaluated under ASTM C1609/C1609M using 150 mm × 150 mm × 500 mm third-point beams; post-crack residual strengths for fibre contents in this range commonly fall between 1.2 MPa and 2.1 MPa at a net deflection of L/400. Jointless panel design should specify a minimum average residual strength ratio of 25 % to 35 % under EN 14889-2:2006, because lower values have been associated with uncontrolled mid-panel crack propagation beneath racking outrigger loads. Batching error greater than ±0.2 kg/m³ is detectable as increased slump loss after 20 minutes, and fibre count per cubic metre should be checked by a wash-out sample on the first 3 loads each day to control batch-to-batch variance. The terminal concrete element is power-trowelled after bleed-water disappearance, and the absence of ferrous fibre staining is relevant for receiving yards where surface appearance is an acceptance criterion under the project quality plan.

How Does Wet-Mix Shotcrete Placement Redistribute Macro-Fibre Orientation?

In sprayed concrete for rock support, Adfil Strux 85/50 is charged into the wet-mix hopper at 4.0 kg/m³ to 7.0 kg/m³ before the alkali-free accelerator is dosed at the nozzle. The critical processing variable is fibre orientation after pneumatic projection: unlike slab concrete, where fibres align predominantly in the horizontal placement plane, shotcrete fibres rotate as they travel from the nozzle to the substrate, producing a near-random in-plane distribution with reduced through-thickness alignment. Panel testing under ASTM C1550-20 uses a 75 mm thick round panel of 800 mm diameter and is preferred because it captures biaxial bending better than a single beam specimen. Energy absorption at 40 mm central deflection for synthetic macro-fibre shotcrete at the upper dosage range is often reported between 280 J and 420 J; however, published data for the specific Strux 85/50 wet-mix configuration is limited, and pre-construction qualification panels should be sprayed on site. The wet-mix process requires a maximum aggregate size of 8 mm to 10 mm; larger limestone or granite particles increase fibre rebound and reduce the effective in-situ fibre content. Rebound losses measured at the receiver are commonly 10 % to 25 % of total shotcrete mass, and the low-density PP/PE fibre rebounds preferentially because of its higher drag-to-mass ratio; the in-situ fibre content may therefore be 0.5 kg/m³ to 1.5 kg/m³ lower than batched unless the nozzle is maintained at 85° to 90° to the substrate. Alkali-free aluminium sulfate accelerators typically produce initial setting times of 2 min to 5 min at 20 °C; the polyolefin fibre does not undergo alkaline hydrolysis in the short term, but the high-pH pore solution above 13.0 is a long-term condition that must be addressed through mix design and curing. The finished application is a temporary or permanent rock-support lining of 80 mm to 120 mm thickness in road tunnels or mine access declines, with the fibre providing post-crack toughness that reduces the required welded-wire mesh layer count by one to two layers.

Thin-Section Precast Elements With Reduced Carbon-Steel Cover

Architectural cladding panels, acoustic barrier shells, and small-diameter drainage channels are produced with an equivalent concrete cover of 10 mm to 15 mm without macroscale carbon-steel mesh when Adfil Strux 85/50 is added at 2.0 kg/m³ to 3.5 kg/m³. The precast mix is usually a self-compacting concrete with a maximum aggregate size of 6 mm to 8 mm, and the fibre is blended in a high-shear planetary mixer after the polycarboxylate superplasticiser has dispersed the cement paste onto the fine aggregates. Demoulding strength of 18 MPa to 22 MPa is reached in 16 h to 24 h under controlled curing at 35 °C; the fibre-reinforced units resist edge damage during stripping because the macro-fibre bridges the narrow lip sections that would otherwise spall under ejection force. Compliance is assessed through EN 14889-2:2006 performance criteria for polymer macro-fibres, with the CE declaration listing fibre geometry, tensile strength, alkali resistance, and the effect on concrete consistency. The terminal units include motorway acoustic barriers with a panel thickness of 100 mm and precast headwalls where conventional steel reinforcement would create galvanic corrosion risk in sulphate-bearing groundwater. Because the elastic modulus of PP/PE macro-fibre is lower than that of steel, the fibre is not a substitute for primary bending reinforcement in load-bearing precast beams or columns; in thin flat elements, however, the fibre’s post-crack flexural behaviour provides damage tolerance for handling and service microcracking. Published data for the specific structural contribution in slender precast sections is limited, so full-scale flexural testing under ASTM C1609/C1609M or EN 14651 should be performed when the fibre contribution is assumed in the design model.

On bus rapid-transit lanes and industrial road intersections where a 100 mm to 150 mm bonded concrete overlay is placed over an existing asphalt or concrete substrate, Strux 85/50 is incorporated at 2.5 kg/m³ to 4.5 kg/m³ to control plastic shrinkage and provide post-crack load transfer in the overlay. The slipform paver or vibratory screed processes the fibre-reinforced concrete at a spread rate of 1.5 m/min to 2.5 m/min, and the fibre must be batched consistently to prevent clumping in the paver’s auger chamber. Field verification for whitetopping usually includes joint efficiency testing and crack-width mapping rather than beam residual strength alone; however, the mix is pre-qualified by ASTM C1550-20 round panel tests to confirm that fibre addition raises the energy absorption at 40 mm central deflection from a plain concrete baseline of 5 J to 10 J to a value above 150 J. The terminal pavement product is a jointed or semi-continuous overlay with saw-cut contraction joints spaced at 2.5 m to 3.0 m, and the synthetic macro-fibre reduces the amount of conventional transverse steel or small-diameter dowel baskets at joint locations. In comparison with steel fibres, the PP/PE product does not produce surface corrosion spots after winter de-icing salt exposure, which is a terminal-service requirement for bus lanes where surface skid resistance is inspected under EN 13036-4. Published data for Strux 85/50 in bonded whitetopping over asphalt is limited; therefore, a test section of at least 200 m² should be placed before full-scale paving.

When Synthetic Macro-Fibre Replaces Steel Fibres in Radio-Frequency-Sensitive Floor Plates

Where high-frequency welding cells, induction charging stations along automated guided vehicle routes, and magnetic resonance imaging halls generate electromagnetic interference or eddy-current constraints, the floor plate mix excludes steel fibres entirely and uses Adfil Strux 85/50 at 3.0 kg/m³ to 5.0 kg/m³. The PP/PE macro-fibre has a volume resistivity above 10⁶ Ω·cm, whereas steel-fibre-reinforced concrete can behave as a partial conductor under damp conditions and attenuate radio-frequency signals. Placement of the fibre-reinforced slab under an overhead travelling crane with a payload of 20 t uses a laser-guided screed and ride-on power trowel; the fresh concrete slump is held at 140 mm to 180 mm to avoid fibre balling in the screed auger. Because the polyolefin fibre does not generate ferrous dust during power trowelling, the finished surface can be sealed with a lithium-silicate densifier after 7 days without the efflorescence associated with steel-fibre oxidation. The design limit is the lower post-crack flexural modulus of polymer fibres: for a suspended floor plate, the fibre does not provide continuous structural tension capacity across negative moment regions, and supplementary reinforcing bars or post-tensioning remain mandatory. The relevant fibre specification remains EN 14889-2:2006, but the project specification should reference ASTM C1609/C1609M third-point beam testing and tabulate the residual flexural strength at L/400 and L/600 deflection points.

Levelling Screeds Need a Different Fibre Dosage Envelope Than Structural Slabs

Levelling screeds in logistics mezzanines, bonded repair overlays on bridge access ramps, and unbonded screeds in refrigerated displays are mixed with Strux 85/50 at 1.0 kg/m³ to 2.5 kg/m³, a lower range than structural slabs because the screed’s primary function is delamination resistance and crack-width control rather than flexural moment transfer. The dry-mix or semi-dry screed is processed through a forced-action paddle mixer, and the fibre is introduced at the beginning of the cycle to allow mechanical dispersion before water is added to the cementitious binder. Because published data for this specific configuration is limited, cyclic freeze-thaw verification under ASTM C666/C666M is required before the screed is exposed to continuous -25 °C service. The terminal construction is a 40 mm to 70 mm thick bonded or unbonded screed that provides a crack-free base for high-density racking legs and forklift transit in cold-chain facilities. Bond strength to the substrate is measured using pull-off tests according to EN 1542, and a minimum bond strength of 1.0 MPa is commonly required; the addition of macro-fibre does not supersede the need for mechanical preparation of the existing concrete surface by captive shot-blasting. The fibre’s specific gravity of 0.91 means that the product is distributed through the full screed thickness rather than settling to the bottom, but the mixing time must be extended by 15 s to 30 s per batch compared with an equivalent unreinforced mix.

For buried stormwater detention chambers and cast-in-place culvert surrounds subject to seasonal wet-dry cycles and de-icing salt runoff, Strux 85/50 is batched at 3.0 kg/m³ to 5.0 kg/m³ to replace light crack-control mesh in zones where conventional reinforcement would require additional concrete cover. The concrete is delivered with a maximum aggregate size of 10 mm to 14 mm and consolidated with high-frequency immersion vibrators; the fibre does not interfere with the vibration path, but over-vibration beyond 15 s per insertion can orient the fibres into horizontal planes and reduce vertical face stability. Durability is governed by EN 206 and ASTM C1433/C1433M for precast box culverts, and the macro-fibre assists in controlling corner and edge cracking during compaction and backfilling. The terminal structures are typically buried stormwater detention chambers and overflow channels where conventional reinforcement would require additional cover of 40 mm to 50 mm against chloride ingress; the synthetic fibre does not reduce code-required cover, but it provides crack-control redundancy without corrosion staining. Published data for Strux 85/50 in buried hydraulic structures is limited; therefore, permeability testing under EN 12390-8 and chloride diffusion profiling under ASTM C1556 should be included in the qualification mix.