Master Builders Solutions MasterFiber 012
Monofilament polypropylene microfibres that intercept plastic-shrinkage cracks at the scale conventional mesh can’t reach — dosed straight into the mix, no cutting or laying required.
What is it?
A 12 mm monofilament polypropylene microfibre, supplied as water-dispersible flakes in pre-weighed 0.6 kg bags, dosed directly into concrete and mortar as secondary (shrinkage/temperature) crack-control reinforcement.
Where is it used?
Readymix and precast concrete, industrial and warehouse floor slabs, screeds, rendering mortars, pavements, shotcrete, water-retaining structures and marine concrete.
Why use it?
Controls plastic-shrinkage and early thermal cracking, is rustproof and alkali-inert unlike steel mesh, and can reduce or replace anti-crack welded wire mesh in floor slabs — cutting labour and placement time.
How is it applied?
Added directly at the batching plant or on site at a standard rate of 0.6 kg per m³ of concrete, then mixed through the full normal cycle time until the fibres disperse evenly through the batch.
About Master Builders Solutions MasterFiber 012
MasterFiber 012 is a monofilament polypropylene microfibre from Master Builders Solutions — the global construction-chemicals brand that grew out of BASF Construction Chemicals — sold as a crack-controlling additive for concrete and mortar rather than a structural reinforcement product. Each fibre is just 18 microns thick and 12 mm long, but because the material is supplied as pre-weighed flakes bound together by a water-soluble sizing agent, a single 0.6 kg bag opens up into millions of individual filaments the moment it hits a wet mix, giving more than 230 m² of fibre surface area per kilogram spread through the batch. That density is the entire point: at the micro-crack scale where plastic shrinkage and early thermal movement actually happen, conventional 6–8 mm diameter reinforcement or welded wire mesh simply isn’t fine enough to intervene, and this is where a monofilament PP fibre earns its place in the mix design.
For Indian site conditions — hot, dry curing windows, RMC trucks sitting in traffic before pour, warehouse floors poured in large uninterrupted bays — the product solves a very specific, very common complaint: hairline map-cracking on floor slabs, screeds and precast units within the first 24–72 hours, long before any structural load has even been applied. Space Arc supplies MasterFiber 012 to readymix plants, precast units and site batching crews across Delhi NCR who need a fast, low-labour way to cut this cracking without the time and cost of cutting, laying and chairing anti-crack wire mesh. It is rustproof, alkali-inert and dosed directly into the drum, which is why RMC quality teams favour it for standard commercial slabs, screeds and rendering work where structural fibre reinforcement isn’t the requirement — just tighter, cleaner, less crack-prone concrete.
The technical insight
The two numbers that matter most on this datasheet are the 18-micron fibre diameter and the 230 m²/kg minimum surface area, because together they explain why a fibre this thin is useful at all. At a standard 0.6 kg/m³ dosage, that surface-area figure means the batch is carrying an enormous number of individual filaments — a fibre count conventional secondary reinforcement can’t match — spread randomly and three-dimensionally through the paste rather than sitting in one plane like a mesh sheet. Plastic-shrinkage and early thermal cracks initiate as micro-tears in the cement paste in the first hours after placement, well before any welded mesh (fixed in a single horizontal plane, and typically at a cover depth chosen for later structural service, not for the top few millimetres where shrinkage cracking starts) can do anything about it; the fibres are already present in that exact zone, bridging the micro-crack the instant it tries to open. That is also precisely why the numbers do not add up to structural reinforcement: a tensile strength of ~350 MPa and modulus of 3,500–3,900 MPa is respectable for a polypropylene polymer, but it is an order of magnitude below reinforcing steel, and random 3D orientation gives isotropic crack-bridging rather than the directional, calculable flexural capacity that a designed rebar or macro-fibre layout provides. It’s a crack-control tool, not a structural one — and every honest spec sheet from this product family says so.
Where it is used
- Readymix and site-batched concrete for slabs, pavements and driveways
- Industrial and warehouse floor slabs as a partial or full replacement for anti-crack wire mesh
- Precast concrete elements — pipes, blocks, kerbs and similar units
- Conventional (dry- or wet-mix) shotcrete
- Screeds, renders and plastering mortars
- Imprinted and decorative concrete, and thin concrete overlays
- Water-retaining structures and marine concrete exposed to early-age thermal movement
- Patch repair mixes and microsilica concrete toppings
Key advantages
- Measurably reduces plastic-shrinkage and early settlement cracking in slabs, screeds and precast
- Can reduce or replace anti-crack welded wire mesh in floor slabs, cutting labour and placement time
- Disperses uniformly through the batch with no cutting, tying, lapping or chairing required on site
- Rustproof and chemically inert — nil alkali, sulphate and chloride content, so no corrosion risk in the finished element
- Improves finishing characteristics, impact resistance and abrasion resistance of the hardened surface
- Does not significantly increase entrained air content, unlike some fibre types
- Fully compatible with all cement types and with other admixtures, including superplasticizers
- Improves fire performance by reducing the incidence of explosive spalling from internal steam pressure during heating
Limitations & considerations
- This is a secondary/microfibre for shrinkage crack control, not a structural fibre — it does not provide the post-crack flexural or load-bearing capacity of macro-synthetic or steel fibre grades
- Does not replace primary structural reinforcement (rebar or structural mesh) required for load transfer or code-mandated design capacity
- Overdosing reduces workability and increases mix cohesiveness, so dosage above the standard 0.6 kg/m³ rate needs an engineering check, not a site estimate
- Needs a full, properly sheared mixing cycle to break down the water-soluble-bound flakes; a short or under-powered mix can leave visible fibre bunching or streaking
- Controls cracking but is not a waterproofing product in itself — any cracks that do form, and construction/movement joints, still need conventional waterproofing or joint treatment
- Technical data for this product is drawn from a Master Builders Solutions regional (BASF Construction Chemicals) datasheet; site teams should confirm current India-specific dosage guidance and packaging with Space Arc or the manufacturer before large-volume ordering
Selection & best practice
Dose at the manufacturer’s standard rate of 0.6 kg per m³ of concrete (conveniently, one 0.6 kg bag per cubic metre at that rate) and treat any change from this as an engineering decision, not a site guess — overdosing reduces workability and makes the mix noticeably more cohesive, which shows up as harder placing and finishing. Add the fibre with the other dry or wet constituents and run the full normal mixing cycle; because the flakes are held together with a water-soluble binder, they need adequate mixing time and shear to fully open up and disperse — a short or lazy mixing cycle is the most common cause of visible fibre bunching or “whiskering” on a trowelled surface. It mixes cleanly with superplasticizers such as MasterGlenium and other admixtures, so there’s no sequencing conflict on a modern RMC batch. Remember this is a crack-control microfibre, not a substitute for structural reinforcement — where a slab or element needs load-bearing steel or macro-synthetic/steel fibre reinforcement, MasterFiber 012 should be specified in addition to that reinforcement, not instead of it, and cracks that do form still need proper joint detailing or waterproofing treatment.
Specifications
| Fibre type / constituent | 100% monofilament polymerised polypropylene |
| Fibre length | 12 mm |
| Fibre diameter | 18 micron |
| Specific gravity | 0.91 g/cm³ |
| Tensile strength | Minimum 350 MPa |
| Young’s modulus | 3,500–3,900 MPa |
| Melting point | 160°C |
| Surface area | 230 m²/kg (minimum) |
| Standard dosage / pack size | 0.6 kg/m³ standard rate; supplied in 0.6 kg water-soluble bags, 30 bags per carton (18 kg/carton) |
Industry use cases
Readymix concrete (RMC) plants
Batch-dosed at 0.6 kg/m³ into standard commercial mixes to cut plastic-shrinkage cracking complaints on slabs and pavements without changing the core mix design.
Industrial & warehouse flooring
Used as a partial or full substitute for anti-crack welded wire mesh in large uninterrupted floor bays, saving mesh-laying labour and time on the pour.
Precast concrete units
Dosed into pipes, blocks, kerbs and similar precast elements to reduce hairline surface cracking during early curing and demoulding.
Screeds, renders & repair toppings
Mixed into screeds, plastering mortars and thin overlays where conventional reinforcement isn’t practical but shrinkage cracking is a known risk.
Water-retaining & marine structures
Specified alongside waterproofing systems to limit early-age thermal and shrinkage cracking in tanks, retaining structures and marine concrete elements.
Frequently asked questions
Can MasterFiber 012 fully replace the welded wire mesh in my floor slab?
What dosage should I use for a typical residential or commercial slab?
Will the fibres be visible on a power-trowelled or exposed concrete finish?
Can it be used together with MasterGlenium or other superplasticizers?
Does adding this fibre change the slump or workability of my concrete?
Is MasterFiber 012 added at the RMC plant or can it be dosed on site?
How we position Master Builders Solutions MasterFiber 012
MasterFiber 012 sits at the fine, secondary-reinforcement end of the wider MasterFiber range from Master Builders Solutions. Where a slab or element needs actual structural or post-crack load capacity rather than shrinkage control, specifiers move up to the brand’s macro-synthetic and steel MasterFiber grades, and MasterFiber 012 is routinely paired with MasterGlenium superplasticizers for workability and MasterKure curing compounds to further cut early moisture loss — the two biggest levers, alongside fibre dosage, for controlling plastic-shrinkage cracking on a hot Indian site. There is no genuine like-for-like Fosroc equivalent in Space Arc’s catalogue today: Fosroc’s fibre-related offering (Renderoc SFR, SFBD, SF and RP252) is fibre-modified repair mortar for reinstating damaged concrete, not a raw loose microfibre additive for fresh readymix — a specifier choosing between the two is really choosing between “fix a defect” and “prevent one,” not between two versions of the same product. In the open Indian market, the closest practical alternatives to a raw PP crack-control fibre are generic monofilament fibres such as RECRON 3S and other locally packed polypropylene microfibres sold by regional additive suppliers; MasterFiber 012 competes on documented, batch-consistent properties (fibre count, tensile strength, dispersion behaviour) and brand-backed technical support rather than on price against these commodity alternatives.
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