Where concrete is placed in jointless ground-supported slabs with bay lengths above 40 m, Adfil Sinta M3019 is dry-charged into the aggregate weigh hopper at 0.9 kg/m³ to 1.5 kg/m³ of fresh concrete. The material is classified under EN 14889-2:2006 as a polymer fibre for concrete and under ASTM C1116/C1116M as a Type III synthetic fibre-reinforced concrete constituent. Plastic shrinkage cracking is assessed by ASTM C1579-21 using a restrained panel insert, not by flexural strength change, because a virgin PP micro fibre at 0.9–1.5 kg/m³ produces minimal post-crack residual strength but alters bleedwater migration and early tensile strain capacity. In downstream production, the fibre is released from the batching hopper together with the first portion of coarse aggregate, mixed dry for 30–60 s, followed by cement, supplementary cementitious material, and the remaining aggregate, then water and a polycarboxylate ether superplasticizer are added; total forced-action mixing ranges from 120 s to 180 s. Field observations on slab pours of 500–1,200 m³ show that adding the fibre onto free water in pan mixers creates matted bundles, whereas charging it with dry aggregate eliminates most unopened bundles. Placing is typically performed with a truck-mounted boom pump and laser screed, then a film-forming curing compound meeting ASTM C309 is applied after power trowelling. Terminal finished product types include jointless warehouse floors, logistics apron slabs, post-tensioned industrial ground slabs, and external hardstanding areas where early-age crack control is the performance requirement.

At dosages above 1.5 kg/m³, batching operators should verify fibre dispersion by washing a 20 L fresh concrete sample over a 4.75 mm sieve and inspecting for retained bundles before discharge, because high-speed pan mixers can compact low-bulk-density PP fibres into agglomerates without dispersing them into the matrix. The lower dosage boundary of 0.9 kg/m³ is set by the minimum fibre count per unit volume needed to influence plastic shrinkage cracking; below that level, published data for PP micro fibres in slab applications show inconsistent crack reduction. Published data for M3019-specific restrained shrinkage curves is limited, so plant trials under ASTM C1579-21 should be used to fix the final dosage for a given slab thickness and evaporation condition. The fibre does not replace dowelled joints, contraction joints, or slab reinforcement for structural load transfer.

Why Is PP Micro Fiber Dosage Kept Below 2.0 kg/m³ in High-Performance Tunnel Segment Castings?

In high-performance concrete for precast tunnel segments with strength class C60/75 to C80/95 and water-cement ratio below 0.35, Adfil Sinta M3019 is batched at 1.2 kg/m³ to 2.0 kg/m³ to support passive fire spalling control rather than hardened-state tensile reinforcement. The governing structural fire design standard is EN 1992-1-2, and fire resistance testing is conducted under ISO 834-1:1999 or a project-specific hydrocarbon fire curve. When exposed to fire, the PP monofilaments melt at 160–170 °C and create an interconnected network of microchannels that releases internal vapour pressure before steam pressure exceeds the heated concrete tensile capacity. The dosage threshold is critical: below 1.2 kg/m³ the melt channel network is not reliably formed across the complete segment cross-section, and above 2.0 kg/m³ low-water-cement-ratio high-performance mixes in high-shear pan mixers show measurable slump loss and increased balling. In segment production, the fibre is introduced with the first half of fine aggregate into the mixer, followed by silica fume, cement, and remaining aggregate; the concrete is discharged into rigid segment moulds, compacted by external vibrators, steam-cured at 60–70 °C for 6–8 h, and demoulded when project-specified early strength is reached. Terminal finished products are precast tunnel ring segments for TBM-driven rail and road tunnels, segmental shaft linings, and cut-and-cover tunnel units.

Field experience from segment plants indicates that screw-fed addition through the silica fume or cement line causes low-bulk-density fibre segregation, so the fibre is introduced only through the aggregate charging hopper. Mixing after fibre addition should not exceed 90 s at high shear when fresh concrete temperature is above 30 °C, because prolonged mixing can raise air content and reduce compressive strength in the already sticky low-water-cement-ratio mixture. A structural limitation is that PP micro fibre at 1.2–2.0 kg/m³ does not provide post-crack tensile or flexural capacity; steel reinforcement, stirrups, or steel fibres must carry all structural loads after cracking under EN 1992-1-1. Published M3019-specific spalling data under hydrocarbon curves is limited, so full-thickness furnace tests are mandatory before the upper dosage is used in fire design.

Sprayed concrete in underground excavation uses Adfil Sinta M3019 at 0.9–1.5 kg/m³ as a plastic shrinkage control fibre in wet-mix shotcrete, where the material is batched centrally and delivered to a portable piston pump with a maximum aggregate size of 8 mm. The governing sprayed concrete standard is EN 14487-1:2005, and the material specification is ASTM C1436/C1436M; energy absorption testing, if specified, is conducted under EN 14488-5 on hardened panels, but the PP micro fibre alone does not deliver the post-crack residual strength required for high energy absorption classes. The production process at the batch plant adds the fibre into the aggregate stream before cement and water, then the wet-mix is discharged into a truck mixer and transported to the spray pump; at the nozzle, a liquid alkali-free accelerator is injected and compressed air is set to maintain a stable spray cone. Terminal application includes 50–100 mm thick temporary support layers in mining drifts, permanent sprayed linings in weak ground, and slope stabilisation shells where early-age cracking of a thin cementitious shell would reduce durability. Field data show that low-shear truck mixing alone after central mixing is not sufficient to disperse fibres if they are dumped into free water, so the batching sequence is the primary dispersion step; a 20 L sample should be taken at the nozzle and washed over a 4.75 mm sieve before accelerator is added to confirm no retained bundles. The fibre does not consistently reduce rebound in all field conditions; rebound is controlled by nozzle angle, air ring pressure, and concrete rheology, and no M3019-specific rebound claim is made here.

In mining operations with haul times above 60 min, the mix may require a mid-range plasticizer re-dosing at the pump hopper to maintain pumpability, but the fibre distribution remains intact if it was properly dispersed during initial mixing. The addition of PP micro fibre to shotcrete does not replace mesh, bolts, or steel fibres where ground support calculations require post-crack bending capacity; designers must separate early-age plastic shrinkage control from structural toughness requirements under EN 14488-5.

When a self-levelling underlayment mix is designed for pump application on multi-storey fast-track sites

For blended calcium sulfoaluminate–Portland cement self-levelling screeds, Adfil Sinta M3019 is dry-blended at 0.05–0.10 % of total dry powder mass, equivalent to approximately 0.6–1.0 kg/m³ of wet compound at a water addition of 6.0–6.5 L per 25 kg bag. Hardened screed conformity is tested under EN 13813:2002, and the fibre function is plastic shrinkage crack reduction at high evaporation rates and at sharp thickness transitions around underfloor heating pipes and floor outlets. In the dry-mix plant, a horizontal ploughshare mixer with independently driven choppers is used; mineral binders and graded fillers are first homogenised for 60 s, then the fibre is added through a loss-in-weight feeder, and final blending continues for a maximum of 180 s to limit fibre attrition and dusting. Site installation uses continuous mixing pumps or batch forced-action paddle mixers, the mixed screed is poured onto a primed substrate, and de-aeration is performed with a spike roller before initial set. Terminal product types include self-levelling floor underlayments from 3–20 mm thickness, bonded bases for resilient and textile floor coverings, and levelling layers over electric or hydronic underfloor heating systems.

The operational boundary for fibre dosage in this application is narrow: above 0.15 % by dry powder mass, fibre-rich surface accumulation reduces trowel finish quality and may increase pump line resistance; below 0.03 %, fibre distribution is too sparse to influence plastic crack formation in layers thinner than 10 mm. Because dry mix is packaged in small bags, batching accuracy of the fibre feeder must be checked hourly, and any deviation above 5 % of target dosage should trigger a line stop. Published data for M3019-specific restrained shrinkage in self-levelling formulations is limited, so release testing should include a restrained plastic shrinkage test aligned with ASTM C1579-21 and full-scale pump trials before site specification.

Factory-produced cement-lime render and basecoat plaster formulations incorporate Adfil Sinta M3019 at 0.3–0.6 kg per tonne of dry mortar, which corresponds to 0.5–1.0 kg/m³ of fresh render at normal machine-spray water addition rates. The finished mortar is tested under EN 998-1:2016, while the fibre as a raw material is covered by EN 14889-2:2006; the dry-mix manufacturer’s Factory Production Control must demonstrate uniform dispersibility and dosage. In production, the fibre is added through a sack-slitting station into a ribbon blender after silica sand and the cement-lime binder have been mixed for 45 s; the total mixing time after fibre addition is 120–180 s. The dry render is then bagged into 25 kg multiwall paper sacks with an internal polyethylene liner to keep moisture content below the binder-critical threshold. On the job site, a continuous mixer-pump or screw pump sprays the render at 10–20 mm thickness in one or two passes, followed by a profile rod and float or sponge finish. Terminal finished products include machine-applied basecoat renders on concrete, clay block, and autoclaved aerated concrete masonry, plus patching mortars used under external insulation systems.

The process condition that limits higher addition is dry-mill heat: PP micro fibre should not be exposed to sustained dryer temperatures above 80 °C before blending because thermal exposure changes fibre stiffness and increases breakage during ribbon blending. As a result, the fibre is added downstream of the drying circuit and not into the hot sand stream. The fibre does not replace reinforcing mesh in crack-prone render systems, and it does not compensate for substrate movement joints or inadequate substrate keying under EN 998-1:2016; its function is limited to reduction of early-age plastic cracking in the soft wet mortar.

Cementitious waterproofing slurries and crack-bridging membrane underlays

A two-component cementitious waterproofing slurry for balconies, terraces, and wetroom substrates uses Adfil Sinta M3019 at 0.3–0.8 kg/m³ of mixed slurry, introduced through the dry component before polymer dispersion and water are added. The liquid-applied membrane system is tested under EN 14891:2017, and the fibre function is to reduce plastic shrinkage microcracking in thin trowel-applied or roller-applied layers over rough substrates. Downstream mixing uses a high-shear paddle mixer at 500–900 rpm; the dry powder containing cement, graded fillers, and fibre is first added to water, then the polymer dispersion is introduced, and mixing continues for 3–5 min to remove lumps and disperse the fibre. Application is by trowel, brush, or roller in two coats with a reinforcement mesh bedded between coats at joints and coves; the total cured thickness typically falls between 2–4 mm. Terminal product types are waterproofing layers beneath ceramic tiling, balcony and terrace membrane systems, and wetroom tanking underlays.

If the fibre dosage exceeds 1.0 kg/m³ in a polymer-modified slurry, trowel application can force fibres to the surface and create a fibrous finish that interferes with tile adhesive film formation; this is the main reason the upper limit is lower than in concrete applications. Below 0.3 kg/m³, the fibre count is insufficient to influence plastic shrinkage in coats thinner than 2 mm. Published data for M3019 in EN 14891-tested formulations is limited, so the formulator should verify wet film cracking behaviour by a restrained panel test and by checking tile adhesive bond strength after membrane curing before commercial release.