About Fosroc Auramix 350 DIS

Fosroc Auramix 350 DIS is a high-performance concrete admixture from the Fosroc Auramix range, engineered for projects that demand both very high water reduction and prolonged workability retention. It belongs to the latest generation of superplasticisers built on polycarboxylic-ether (PCE) chemistry, where long lateral polymer chains physically separate and disperse cement grains far more effectively than older naphthalene or melamine sulphonate plasticisers. The “DIS” designation denotes the instantly dispersible grade — the admixture mixes into the gauging water immediately, which simplifies dispensing at busy ready-mix plants and on site.

In practical terms, Auramix 350 DIS lets a concrete producer pull a large volume of water out of the mix while keeping the slump and flow needed for placement. That single action drives several benefits at once: a lower water-cement ratio raises compressive strength and durability, the dispersed cement hydrates more completely, and the retarding action holds workability open long enough for transit, pumping and placement in Indian ambient temperatures. Fosroc’s own classification places it as a high-range, water-reducing and retarding admixture, suited across both low- and high-grade concrete work.

For a Fosroc authorised distributor and applicator like Space Arc Engineering, Auramix 350 DIS is a workhorse product specified on RMC supply, high-rise pumping and durability-critical structures. This page explains what it is, where it fits, how to use it correctly, and how it compares to neighbouring products in the Auramix family and to competing brands available in India.

The technical insight

The performance of Auramix 350 DIS comes from steric dispersion rather than only electrostatic repulsion. A PCE molecule anchors onto the cement particle while its long ethylene-oxide side chains project outward, creating a physical “brush” that keeps grains apart and frees the water otherwise trapped in flocculated cement clusters. This exposes far more cement surface to hydration, which is why the same mix can be re-engineered three ways: keep water and cement constant to gain workability, cut water to gain strength, or cut cement to gain economy while holding strength. The product carries no added chloride (conforming to IS:456 requirements for reinforced concrete) and does not entrain significant air, so it will not compromise reinforcement passivation or the design air content. Its built-in retardation extends the dormant period of hydration, which is genuinely useful for long haul distances and pumping in hot weather, but it also means setting and early strength gain are slower in cold conditions — mixes must be trial-tested at the actual site temperature, cement source and SCM (fly ash/GGBS) combination, because PCE response is highly sensitive to cement chemistry and fines content.

Where it is used

• High-rise and pumped concrete requiring delivery to greater heights without slump loss
• Ready-mixed concrete (RMC) needing extended workability retention over transit time
• High-strength and high-performance concrete (M40 and above) at low water-cement ratios
• Concrete incorporating cement replacements such as fly ash and GGBS
• RCC for foundations, rafts, columns, beams, slabs and shear walls
• Precast and prestressed elements where early strength and finish quality matter
• Durable concrete for marine, water-retaining and aggressive exposure conditions
• Mass concrete pours where retardation helps control heat and cold-joint risk

Key advantages

• Very high water reduction enabling higher compressive strength and improved durability
• Long workability retention that suits long transit, pumping and placing windows in Indian conditions
• Instantly dispersible grade for easy, quick dosing into gauging water at plant or site
• Low-viscosity formulation that supports pumping different concrete grades to greater heights
• Lower water-cement ratio reduces drying shrinkage cracking and improves water impermeability
• Allows cement-content optimisation, lowering cost and embodied carbon without losing strength
• Chloride-free as per IS:456, safe for reinforced and prestressed concrete
• Better resistance to carbonation and reduced creep, improving long-term structural performance

Limitations & considerations

• Retarding action slows set and early strength gain, which can be a drawback in cold weather or fast-cycle precast unless adjusted
• PCE admixtures are sensitive to cement source, fines and SCM content — every mix must be trial-tested before site use
• Overdosing can cause excessive retardation, segregation or bleeding; accurate dispensing equipment is essential
• Not an air-entraining agent — separate air entrainment is needed for freeze-thaw exposure
• Performance and compatibility should be confirmed when blending with other admixtures (e.g. air entrainers, accelerators)
• Liquid product requires protection from freezing and from temperatures outside the recommended storage band
• As a high-range plasticiser it targets water reduction/strength, not waterproofing, curing or mould release — those need dedicated products

Selection & best practice

Specifications

Industry use cases

How we position Fosroc Auramix 350 DIS

Fosroc Auramix 350 DIS sits in the high-performance PCE superplasticiser tier of the Auramix range, where water reduction and long workability retention both matter. It is closely related to the standard Auramix 350 (the non-dispersible counterpart) and to retarding grades such as Auramix 300 and the broader Auramix DIS line; for very high-flow or self-compacting work, higher Auramix grades or Fosroc’s Conplast/Structuro families may be more appropriate, and projects needing curing compounds, waterproofing or mould release should use dedicated Fosroc products (e.g. Concure curing membranes, Conplast water-reducers, Reebol mould-release agents) rather than this admixture. Against competitors, credible alternatives in the Indian market include Sika’s PCE-based ViscoCrete superplasticisers, BASF/Master Builders Solutions MasterGlenium, Dr. Fixit (Pidilite) high-range admixtures, and STP (Shalimar) plasticisers — each broadly comparable in chemistry, with the right choice driven by cement compatibility, trial-mix results, technical support and supply reliability. As a Fosroc authorised distributor and applicator, Space Arc Engineering positions Auramix 350 DIS for clients who want proven Fosroc performance backed by local trial-mix guidance, dosage optimisation and dependable delivery across Delhi NCR and Pan-India.

Related Concrete Admixtures products

View all Concrete Admixtures products →