At a precast plant producing tunnel segments, SikaFiber Novomesh 950 (also designated SikaFiber Force 950 in certain market jurisdictions) is charged through a bag-breaking feeder interlocked with the aggregate weigh belt so that the fibre stream enters the mixer during the latter half of coarse aggregate loading. The blended macro/micro package is supplied as a disintegrating bag that is degraded by mixing action; the micro fraction disperses into the mortar phase while the macro fraction remains within the coarse aggregate skeleton. Dosage is maintained at 4–6 kg/m³ because this range corresponds to post-crack residual strength requirements under EN 14651:2012 and ASTM C1609/C1609M-19, while doses below 3 kg/m³ do not reliably bridge cracks wider than 0.2 mm in segment flexural tests. The concrete matrix is a C50/60 mix with w/c ratio 0.36, total air content 1.5–2.5%, and a target discharge slump of 120 ± 20 mm. When the fibre dosage increases to 6 kg/m³, placement crews observe a slump reduction of 20–40 mm despite increased polycarboxylate ether dosage of 0.2–0.4% by weight of cement, especially if the mix is held in transit for more than 45 min. Segments are cast in automated carousel moulds fitted with 50 Hz external vibrators; concrete containing the fibre blend requires an additional 5–10 s of vibration per mould side to release air trapped behind macro fibres at the form face. Stripping at 8–10 h with accelerated steam curing at 55–60 °C is not adversely affected, but edge spalling can occur if the macro fibre density at the mould edge exceeds 8 kg/m³ due to operator over-dosing. Compliance is documented under EN 14889-2:2006 with CE marking under Regulation (EU) No 305/2011, and production records include batch fibre mass verification against the ±0.5 kg tolerance of the automated feeder.

What Controls Post-Crack Residual Strength in Ground-Supported Industrial Slabs?

The selection of the fibre dosage in ground-supported slabs is governed by residual strength rather than compressive strength. For slabs exposed to hard-wheeled forklift traffic and high-bay racking, SikaFiber Novomesh 950 is batched at 3–5 kg/m³ when the macro fraction replaces welded wire mesh and the micro fraction targets plastic shrinkage cracking. Post-crack performance is evaluated with EN 14651:2012 using notched beams loaded at a constant CMOD rate of 0.05 mm/min until 0.5 mm; project specifications typically require f_R,1 ≥ 1.5 MPa and f_R,3 ≥ 1.0 MPa at 2.5 mm CMOD for slabs designed to replace A142 mesh. In North American practice, ASTM C1609/C1609M-19 is applied and the fibre blend is evaluated for f₆₀₀ and f₁₅₀ residual flexural strengths. Plastic shrinkage cracking is screened under ASTM C1579-21; a dosage of 3 kg/m³ of the micro component is accepted when the crack width is limited to 0.2 mm at 24 h. The fresh concrete is pumped through a 125 mm nominal steel pipeline with an S-valve piston pump; delivery pressure is kept below 85 bar because pressure spikes occur at fibre accumulations in reducers. At a dosage of 4 kg/m³, the slump can drop by 25–50 mm from a 150 mm reference, and the plant must add 0.2–0.5% polycarboxylate ether by cement weight when the aggregate moisture drops below 2%. If the fine aggregate-to-total aggregate ratio is below 0.42, macro fibres may form balls under high-speed mixing; the ratio should be held at 0.45–0.50 for continuously mixed slabs. Laser screed placement proceeds in strips of 3–4 m width, and early-age saw cuts are executed when the concrete reaches a compressive strength of 3.5–5.0 MPa or before 18 h in warm weather. The terminal slab is not freed from joint design; diamond dowel baskets at 300 mm centres are retained at free construction joints for load transfer.

Wet-mix sprayed concrete for primary rock support introduces different placement constraints. The dual fibre package is added at the batch plant before the air-entraining admixture, because delayed addition can cause the micro fibre fraction to float onto the mixer surface and enter the pump hopper as a segregated mass. Typical fibre dosage is 4–7 kg/m³ in a base mix with 8 mm maximum aggregate, cement content 400–450 kg/m³, silica fume 20–30 kg/m³, w/c ratio 0.40–0.45, and superplasticizer adjusted to maintain a pumpable slump of 140–180 mm at the hopper. The wet-mix machine is a piston pump with S-valve and 100–125 mm delivery line; concrete output is matched to 10–15 m³/h and nozzle air is set at 5–8 m³/min at 6–7 bar. Set accelerator is injected at the nozzle at 3–6% by weight of cement, depending on ground water inflow and overhead thickness. The macro fibre fraction resists tensile stress after the lining has undergone displacement, while the micro fibre fraction suppresses plastic shrinkage cracking near the accelerator-enriched surface. Rebound increases when the nozzle distance exceeds 1.5 m or when the nozzle angle falls below 70° to the receiving surface; fibre rebound is visually detectable as protruding macro fibres in the rebound pile. Blockage risk rises at macro fibre dosage above 7 kg/m³ in a 100 mm line, especially if the pump stroke volume is below 0.5 L per stroke; a 125 mm line and full-flow couplings are specified for continuous underground operation. The placed shotcrete is tested under EN 14487-1:2005 for conformity and under EN 14488-3 for flexural toughness; sprayed panels are produced on site and cut into beams. Published data for this exact hybrid geometry in permanent NATM linings is limited, so production trials should compare the selected dosage against a reference steel-fibre shotcrete at the same residual strength class.

When Dry-Cast Precast Pipes Are Demoulded Immediately After Packerhead Compaction

Dry-cast concrete pipe and box culvert production operates at zero-slump consistency and immediate demoulding, which changes the fiber distribution behaviour. SikaFiber Novomesh 950 is batched into a countercurrent mixer after the aggregate but before the cement, at 3–5 kg/m³, and the wet mixing time is extended to 90–120 s because the macro fraction must be coated with dry fines to prevent fibre-on-fibre friction in the packerhead compaction zone. In dry-cast pipe, the w/c ratio is 0.26–0.34 and the cement content is 350–400 kg/m³; the macro fibres are too stiff to be compacted into the densely packed ring without losing green strength if the dosage exceeds 5 kg/m³. Vertical vibration is applied at 50–60 Hz with a packerhead or rollerhead machine, and the compaction time is extended by 5–10 s per pipe relative to the unreinforced control. The terminal products are storm drains, culverts, and manhole risers produced under ASTM C76 and EN 1916:2002. Crack width control is measured under ASTM C497 three-edge bearing; the fibre-reinforced sections are specified for 0.25 mm crack width criteria in mildly aggressive soils. The micro fibre fraction reduces surface edge chipping during demoulding and handling, but does not replace the steel cage in high-load classes where D-load exceeds 75 kN/m. When ambient temperature falls below 10 °C, the dry-cast producer must extend the pre-cure interval before steam introduction because the synthetic fibre surface can act as a nucleation point for water condensation on the exposed pipe crown. If fibre dosage exceeds 5 kg/m³, green springback after compaction can reduce the pipe wall thickness by 1–2 mm; production trials should verify the mandrel diameter and yoke pressure against the densified fibre-bearing mix.

Heavy-Duty Pavement Joints and Transitions in Container Yards

Container yard pavements are placed by slipform or fixed-form methods in widths of 4.5–6.0 m and thicknesses of 200–250 mm. SikaFiber Novomesh 950 is dosed at 4–6 kg/m³ in C30/37 concrete with a 0.42 w/c ratio and 5.5% air content for freeze-thaw exposure. The fibre is introduced in a continuous mixer at a metering tolerance of ±0.5 kg/m³; the mixing time after fibre addition is 60 s for a 2.0 m³ twin-shaft mixer. In slipform paving, the macro fibre fraction stiffens the fresh mix and can cause edge slump behind the paver pan if the mortar volume is below 28%; therefore, the fine aggregate content is increased by 2–3% relative to the unreinforced control mix. Joint design is not eliminated by the fibre blend. Transverse contraction joints are sawed at intervals of 4.5 m and 1/4 of the slab depth, and load-transfer dowels are installed at 300 mm centres for slabs subject to straddle carrier wheel loads. The hybrid fibre package supports crack-width control at the joint corners, but does not replace structural load transfer. Compressive and flexural strength are tested under EN 12390-3:2019 and EN 12390-5:2019; fibre distribution is verified during a pre-construction trial by washing out 50 kg samples from sequential mixer discharge and counting macro fibres. A recorded variance above ±8% between samples triggers a change in the fibre dosing sequence. For refrigerated container stacking areas, the slab is placed as a single layer to avoid cold joints; the fibre-bearing concrete is insulated and cured under ASTM C171 for 7 d to reduce early-age shrinkage. At ambient temperatures above 30 °C, the saw cut timing is brought forward to 6–8 h because the micro fibre fraction does not prevent thermal contraction cracking once the concrete begins to cool.

Composite floor slabs on profiled steel decking receive the hybrid fibre addition at the ready-mix plant after the first 20% of the mixing water has been added, because the micro component competes with cement for wetting and can form low-density agglomerates at the discharge gate. The dosage is 2–5 kg/m³ for slabs of 50–75 mm depth over trapezoidal or re-entrant deck profiles. Pumping is carried through a 100–125 mm line at a concrete output of 20–30 m³/h; the macro fibre fraction increases the dynamic yield stress of the fresh concrete, so the pump pressure limit is set at 70 bar and the line is cleaned when the concrete remains static for more than 20 min. The terminal composite slab uses the macro fibres to distribute post-cracking tensile stresses in the sagging region between the steel deck ribs, while the micro fibres limit plastic settlement cracks above the deck crests. For fire resistance, the polyolefin micro fraction is evaluated for spalling mitigation under EN 1363-1:2020 because the fibres leave capillary channels after melting at approximately 160 °C; however, the fibre blend cannot replace the welded mesh required by EN 1994-1-1:2004 for fire-exposed composite slabs. Shot-fired fasteners and through-deck studs are installed after the fibre-reinforced concrete has developed 70% of the specified compressive strength; early installation at lower strength can disturb the macro fibre orientation at the deck interface. On high-rise projects with repetitive pours, the fibre is pre-blended into bulk bags and discharged through a screw feeder at 0.5–1.0 kg/s into the mixing truck, which reduces batch-to-batch variation to ±0.3 kg/m³. The surface is finished with a power float after bleeding ceases; the micro fibre fraction can reduce bleed water by 10–20%, so finishers must begin machine trowelling earlier than in plain concrete.