About Fosroc Auramix 363

Fosroc Auramix 363 is a new-generation concrete admixture engineered for powerful water reduction with no loss of workability or performance, enabling the production of high-fluidity concrete. It sits within Fosroc’s well-known Auramix 3-series of polycarboxylic-ether (PCE) superplasticisers, the same polymer family as siblings such as Auramix 350 and Auramix 300 Plus, which use long-side-chain PCE molecules that disperse cement grains by an electrostatic-plus-steric mechanism rather than by the older sulphonate-based chemistries.

In practical terms, Auramix 363 lets a concrete producer remove a significant slice of mixing water from a batch while keeping the mix fluid, cohesive and pumpable. Lowering the water/cement ratio at the same workability is the single most effective lever for raising compressive strength and durability, so the admixture is used both to gain strength at a fixed flow and to gain flow at a fixed strength, depending on the job. Fosroc specifically positions Auramix 363 for ready-mixed concrete with high fly-ash content and for wet-sprayed concrete, and notes that it can be used in synergy with conventional plasticisers where a tailored slump-retention or cost profile is needed.

For Indian sites, this combination is valuable. A great deal of structural and infrastructure concrete here is designed with substantial fly-ash replacement for durability, sustainability and cost; high-fly-ash mixes can be sluggish and slow to gain early strength, and a PCE superplasticiser that keeps them fluid and helps early strength is directly useful to RMC suppliers and precast yards. For tunnelling, slope stabilisation and repair, wet-sprayed concrete demands a pumpable, well-dispersed base mix before accelerator is introduced at the nozzle, which again plays to this admixture’s strengths.

Space Arc Engineering supplies Fosroc Auramix 363 as an authorised Fosroc distributor and applicator across Delhi NCR and Pan-India, with technical support on dosage trials, mix optimisation and compatibility for ready-mix, precast and sprayed-concrete applications. Because Auramix 363 is part of Fosroc’s international Auramix range, the exact graded data values applicable to your supply and project should always be confirmed against the current product-specific Technical Data Sheet (TDS) for your region before specification.

The technical insight

Polycarboxylic-ether superplasticisers like Auramix 363 work by a different mechanism from older sulphonated naphthalene (SNF) or melamine (SMF) superplasticisers. The PCE backbone adsorbs onto the cement grain while long grafted side-chains project outward, generating steric hindrance on top of electrostatic repulsion. This combined dispersion frees the water otherwise trapped in cement flocs, so far less water is needed for a given flow, and the molecule structure can be engineered for either high early slump or extended slump retention. The result is high water reduction (typically well above what plasticisers achieve) and the ability to make high-fluidity, near-self-levelling concrete at a low water/binder ratio. In high-fly-ash mixes the PCE helps disperse both the cement and the finer fly-ash particles, improving cohesion and finish; pairing the admixture with fly ash and a low w/c is what drives the durability and reduced-permeability benefits. The trade-off is that PCE admixtures are sensitive to dosage, water content and material variability, so dosage must be dialled in by trial mix rather than copied between jobs.

Where it is used

• High-fly-ash ready-mixed concrete requiring high fluidity without bleed or segregation
• Wet-sprayed concrete (shotcrete) for tunnel linings, slope stabilisation and repair
• Pumped concrete for high-rise and long-distance placement where flow and cohesion matter
• Precast and factory concrete needing high early strength for faster mould turnaround
• High-performance structural concrete designed at low water/binder ratio for strength and durability
• Flowable and near-self-compacting mixes for congested reinforcement and complex formwork
• Use in synergy with conventional plasticisers to tune slump retention and cost

Key advantages

• Strong water reduction at equal workability, lowering water/cement ratio and raising strength
• Maintains high fluidity and workability without loss of performance
• Supports higher early and ultimate compressive strength, aiding faster precast cycles
• Improves pumpability and cohesion, reducing segregation in flowable mixes
• Particularly suited to high-fly-ash and supplementary-cementitious mixes
• Denser, lower-permeability concrete for improved durability
• Can be combined with plasticisers for tailored slump-retention and economy
• Liquid form disperses instantly for easy, repeatable batching

Limitations & considerations

• Dosage is sensitive and material-dependent; overdosing PCE can cause retardation, bleeding or segregation, so site trials are essential
• Performance varies with cement source, fly-ash quality, aggregate and ambient temperature
• Not an accelerator, air-entrainer or waterproofing agent on its own; combine with the right complementary admixture for those functions
• Slump-retention behaviour must be matched to haul time and placing conditions
• PCE chemistries can be incompatible if blindly mixed with other-family admixtures; confirm compatibility before combining
• Graded technical values for the specific regional supply must be confirmed against the current Fosroc TDS rather than assumed
• Should be protected from freezing and stored within the manufacturer’s recommended conditions and shelf life

Selection & best practice

Specifications

Industry use cases

How we position Fosroc Auramix 363

Auramix 363 sits in the mid-to-upper tier of Fosroc’s Auramix superplasticiser range, alongside PCE siblings such as Auramix 350, Auramix 300 and Auramix 300 Plus, with its distinguishing niche being high-fly-ash ready-mix and wet-sprayed concrete that must stay highly fluid. Where a project needs a retarding low-viscosity PCE, Auramix 300 may be more appropriate; for general high-performance superplasticising, Auramix 350 or 400 are common choices, and conventional plasticiser grades (the Auramix 2-series) cover lower-spec, cost-driven mixes. It pairs naturally with other Fosroc concrete-technology products such as Conplast plasticisers/retarders, Auramix DIS-type dispersants, and sprayed-concrete accelerators in shotcrete systems. Among credible alternatives, Sika’s ViscoCrete PCE superplasticiser range, BASF/Master Builders Solutions MasterGlenium, and other PCE high-range water reducers occupy the same technical space; Dr. Fixit (Pidilite) and STP are stronger names in waterproofing and protective coatings than in high-range PCE admixtures, so they are usually complementary rather than direct substitutes here. Final product selection should follow a project-specific trial and the current TDS, and Space Arc Engineering can advise on the best-fit Fosroc admixture for a given mix and exposure class.

Related Concrete Admixtures products

View all Concrete Admixtures products →