About Fosroc Auracast 400

Fosroc Auracast 400 sits in Fosroc’s Auracast family of polycarboxylate-ether (PCE) high-range water reducers, but unlike the precast-focused grades in the range it is developed expressly for concrete flooring. The chemistry is described by Fosroc as a unique combination of the latest generation of polycarboxylate polymers that act synergistically to outperform conventional superplasticisers – in plain terms, multiple PCE polymers are blended so the admixture disperses cement particles efficiently, holds workability, and gives the contractor a slab that flows, places and finishes predictably.\n\nFloor concrete is an unusual application for a superplasticiser. A floor laid in a warehouse, factory or distribution centre has to be highly workable for placing and levelling, yet must set on a controlled, repeatable timeline so the laying crew can power-float and trowel to a planned schedule without the surface running ahead of – or behind – them. Auracast 400 is tuned for exactly that balance: high slump and good cohesion in the plastic state, consistent setting even at high workability, and minimal bleed so the surface stays closed when steel or polymer fibres are present. The result is fewer cold joints, fewer rushed pours and a more uniform finished surface.\n\nThe admixture works without added chloride, so it is safe for steel-reinforced and fibre-reinforced floors. It is engineered to perform robustly across different cement sources and types – a real benefit in India, where OPC and PPC supply and blended cements vary from region to region and batch to batch. For contractors, consultants, architects and procurement teams specifying floors, Auracast 400 is the admixture that lets you treat the floor pour as a managed process rather than a race against the set.

The technical insight

The performance of Auracast 400 comes from how polycarboxylate-ether polymers disperse cement compared with older naphthalene or melamine sulphonate plasticisers. A PCE molecule has a charged backbone that adsorbs onto the cement grain and long side chains that project outward; those side chains create steric (physical) repulsion between particles in addition to the electrostatic charge effect. This steric mechanism keeps cement grains separated for longer, releasing trapped water and delivering high slump at a low admixture dose – which is why PCE superplasticisers are far more efficient per litre than legacy chemistries. What distinguishes a flooring grade like Auracast 400 from a general or precast PCE is the balance of those polymers: the blend is set up to give flow and cohesion without the rapid slump loss or fast set that would shorten the finishing window, and without the bleed that opens up a slab surface when fibres are used. In practice that translates to a slab that stays workable long enough to lay and level, sets on a predictable curve so the power-float and trowel passes can be timed, and finishes closed and dense. As with all polycarboxylate admixtures, trial mixes with the project’s actual cement, sand, aggregate and water are essential – PCE chemistries are sensitive to fines content and cement chemistry, and the optimum dose is established by trial, not assumed.

Where it is used

• Industrial and warehouse floor slabs requiring a power-floated or trowelled finish
• Ready-mixed concrete for floors delivered and dosed on site in the truck mixer
• Dry-batched flooring concrete where consistent dispersion on site is critical
• Steel-reinforced floor slabs (chloride-free, safe around embedded steel)
• Fibre-reinforced concrete floors where bleed control keeps the surface closed
• Large-area pours that must be finished to a planned laying and finishing schedule
• Floors cast with variable or mixed cement sources requiring robust, repeatable workability

Key advantages

• Excellent and consistent cement dispersion, including in dry-batched concrete and ready-mix truck mixers on site
• High workability and slump achieved at low dosage, improving admixture efficiency and cost per cubic metre
• High slump combined with improved cohesion – a flowable yet stable floor concrete
• Consistent setting at high workability, letting contractors finish to a planned schedule
• Reduced undesirable bleed, important when steel or polymer fibres are used
• Robust performance across different cement sources and types – valuable for variable Indian cement supply
• Chloride-free formulation, ideal for concrete containing embedded reinforcement

Limitations & considerations

• Optimised for concrete floors and slabs – not a general-purpose or precast superplasticiser; choose the right Auracast grade for the application
• As a polycarboxylate admixture, performance is sensitive to cement chemistry and fines; site trial mixes are essential to fix the correct dosage
• Overdosing can cause excessive retardation, segregation or bleed – dosing must be measured accurately, not estimated
• Not a standalone waterproofing, curing or corrosion-inhibiting product; combine with the appropriate curing compound and protection system
• Liquid admixture requires protection from freezing and storage within the recommended temperature range; confirm shelf life on the current batch
• Published numeric properties (specific gravity, exact dosage band, standard compliance) must be confirmed against the current local Fosroc Technical Data Sheet before specification

Selection & best practice

Specifications

Industry use cases

How we position Fosroc Auracast 400

Auracast 400 is the flooring-focused member of Fosroc’s Auracast polycarboxylate superplasticiser family. Within the Fosroc catalogue it complements rather than replaces the general-purpose Auramix superplasticisers (such as Auramix 400) and the precast-oriented Auracast grades (Auracast 200, 280, 300 and the high-early-strength precast lines), and on a real floor project it is typically specified alongside a Fosroc curing membrane like Conplast or the Concure range to manage early moisture loss. Against the wider Indian market it competes with flooring-grade PCE superplasticisers from Sika (the Sika ViscoCrete range), Master Builders Solutions (MasterGlenium), Dr. Fixit (Pidilite’s admixture line) and STP, all of which offer high-range water reducers for slab and floor concrete. The honest position is that no single admixture is automatically best for every floor – the right choice depends on the cement, the finishing method and the placing schedule. Auracast 400’s particular strength is that it is engineered for the flooring use-case, pairing high slump and low bleed with a controlled set so contractors can finish to a plan; for any specification, confirm the current grade properties and standard compliance with Space Arc Engineering and a project trial mix before committing.

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