Fosroc Auramix 403
PCE-technology high-range water reducer engineered for self-compacting and pumped concrete with extended workability retention.
What is it?
Auramix 403 is a high-range water-reducing concrete admixture (superplasticiser) built on Fosroc’s polycarboxylic ether (PCE) technology, designed for high water reduction and long slump retention in modern concrete.
Where is it used?
Used in ready-mix plants and on site for self-compacting concrete (SCC), pumped concrete to upper floors, and high-performance structural concrete in raft foundations, piles, columns, beams and slabs.
Why use it?
It delivers strong water reduction at low viscosity, retains workability long enough for transit and pumping, and works with GGBS, fly ash and microsilica blends to produce dense, durable, low-permeability concrete.
How is it applied?
Dispensed into the mix water or gauging water at the batching plant (never onto dry cement), at a trial-established dosage typically in the 0.5-3.0 litres per 100 kg of cementitious material band for the Auramix 4xx series.
About Fosroc Auramix 403
Fosroc Auramix 403 belongs to Fosroc’s flagship Auramix family of new-generation superplasticisers, the same range that includes Auramix 300, 350, 400, 450 and 500. It is formulated on polycarboxylic ether (PCE) technology — a comb-shaped polymer with a charged backbone and long lateral chains that adsorb onto cement particles and push them apart through a combination of electrostatic and steric repulsion. The practical result is that far less mixing water is needed to achieve a given flow, which is exactly what a low water-to-binder ratio, high-strength, durable concrete demands.
Within the Auramix line-up, the 403 grade is positioned for jobs where high water reduction has to be combined with long workability retention — the everyday reality of commercial concrete that is batched at a plant, carried by transit mixer through Delhi NCR or inter-city traffic, and then pumped to height before placing. Fosroc specifically lists Auramix 403 for self-compacting concrete, pumped concrete, concrete requiring extended slump life and high-performance concrete, and notes its low viscosity makes it well suited to pumping different concrete grades to higher floors.
For contractors, RMC producers, consultants and architects working on Indian projects, the important point is that Auramix 403 is a single admixture that lets you cut water, hold workability and still build with supplementary cementitious materials. Fosroc states it is compatible with all common cement-replacement materials — GGBS (GGBFS), fly ash and microsilica — which is increasingly non-negotiable now that blended cements and low-clinker mixes are standard for both cost and durability reasons. The reduced water content translates into higher early and ultimate strength, a higher elastic (E) modulus, lower permeability, reduced drying shrinkage and creep, better adhesion to reinforcement and prestressing steel, and improved resistance to carbonation and aggressive environments. As an authorised Fosroc distributor and applicator, Space Arc Engineering supplies Auramix 403 with batching guidance and trial support so the dosage is dialled in against your actual cement, aggregates and ambient temperature rather than a generic figure.
The technical insight
The performance of Auramix 403 comes from PCE dispersion chemistry rather than the older sulphonated-naphthalene (SNF) chemistry used in earlier-generation plasticisers. At the start of mixing, the negatively charged polymer backbone is attracted to positively charged sites on hydrating cement grains; the polymer adsorbs and the long side chains then physically hold particles apart (steric hindrance) in addition to the electrostatic charge effect. Because the side chains keep releasing dispersion capacity over time, a PCE such as Auramix 403 gives both immediate water reduction and a slower loss of slump than naphthalene-based products — the mechanism behind its long workability retention. The trade-off contractors must respect is that PCE admixtures are dosage-sensitive: too little and you under-disperse; overdose and you risk delayed set and bleeding/segregation, which is why Fosroc insists optimum dosage is fixed by site trials. Auramix 403 is supplied as a ready-to-use liquid that is added to the mix water; it is a non-chloride, low-alkali admixture, so it does not introduce a corrosion risk to embedded steel. In line with the rest of the Auramix 4xx PCE series, it is designed to meet the high-range water-reducing requirements of IS 9103 and ASTM C494 (Type F / Type G depending on dosage), making it specification-friendly for Indian structural concrete.
Where it is used
- Self-compacting concrete (SCC) for congested reinforcement and architectural finishes
- Pumped concrete delivered to upper floors of high-rise and commercial buildings
- High-performance and high-strength structural concrete at low water-binder ratios
- Ready-mix concrete requiring long workability/slump retention through transit and placing
- Blended-cement concrete using GGBS, fly ash or microsilica
- Durable concrete for foundations, rafts, piles, columns, beams and floor slabs
- Concrete where reduced shrinkage, creep and permeability are specified for long service life
Key advantages
- PCE technology gives high water reduction at low dosage for higher strength and durability
- Long workability retention suited to transit-mixed and pumped concrete
- Low viscosity aids pumping of varied grades to higher floors
- Fully compatible with GGBS, fly ash and microsilica blended mixes
- Produces denser concrete with lower permeability and better carbonation resistance
- Higher elastic modulus and improved bond to reinforcing and prestressing steel
- Reduces drying shrinkage and creep, improving long-term durability
- Chloride-free and low-alkali — safe for reinforced and prestressed concrete
- Meets IS 9103 and ASTM C494 (Type F/G) for specification compliance
Limitations & considerations
- Dosage is sensitive and must be established by site trials with actual materials
- Overdosing can cause delayed setting and segregation/bleeding
- Not an air-entraining agent — use a separate AEA where freeze-thaw resistance is needed
- A water reducer, not a waterproofing admixture; pair with integral waterproofing where required
- PCE performance can be affected by changes in cement chemistry, SCM type and ambient temperature
- Add to mix/gauging water only — never dose directly onto dry cement
- Must be protected from freezing and stored within the recommended temperature range to preserve shelf life
Selection & best practice
Always fix the optimum dose by laboratory and field trials using your project’s exact cement, supplementary cementitious materials, aggregates and site temperature, starting within the Auramix 4xx band of about 0.5-3.0 litres per 100 kg of cementitious material. Dispense Auramix 403 into the mix water or final gauging water using calibrated dispensing equipment, never onto dry cement, and avoid manual top-dosing on site that can tip the mix into overdose, delayed set or segregation. Run trial mixes to confirm slump retention over the actual transit-plus-pumping time before bulk production, and re-check the dose if you switch cement source, SCM proportion or face a marked change in ambient temperature. Store drums upright, sealed and protected from direct sun and frost, and use older stock first. For a complete system on durability-critical jobs, combine with the appropriate Fosroc curing compound and, where water-tightness is specified, an integral waterproofing admixture rather than relying on the superplasticiser alone.
Specifications
| Product type | High-range water-reducing concrete admixture (superplasticiser) |
| Base chemistry | Polycarboxylic ether (PCE) technology |
| Primary uses | Self-compacting concrete, pumped concrete, high-performance concrete, long workability retention |
| Appearance (Auramix 4xx series) | Light yellow coloured liquid |
| pH (Auramix 4xx series) | Minimum 6.0 |
| Volumetric mass / specific gravity (Auramix 4xx series) | approx. 1.09 kg/litre @ 20 C |
| Chloride content | Nil to IS 456 |
| Alkali content (Auramix 4xx series) | Typically less than 1.5 g Na2O equivalent per litre |
| Typical dosage (Auramix 4xx series) | 0.5 to 3.0 litres per 100 kg of cementitious material (confirm by trial) |
| SCM compatibility | GGBS (GGBFS), fly ash and microsilica |
| Standards | Designed to IS 9103 and ASTM C494 (Type F / Type G by dosage), Auramix PCE series |
| Packaging (Auramix 4xx series) | Typically 200 litre drums and bulk tanker |
| Shelf life (Auramix 4xx series) | Up to 24 months when stored within recommended temperature range |
Industry use cases
Ready-Mix Concrete (RMC)
Holds slump through transit and pumping so plant-batched concrete arrives and places at design workability without site water addition, supporting consistent strength across deliveries.
High-Rise & Commercial Construction
Low-viscosity PCE dispersion enables pumping concrete to upper floors and placing self-compacting mixes around congested reinforcement with minimal vibration.
Infrastructure & Foundations
Used in rafts, piles, columns and beams to achieve low water-binder, high-durability concrete with reduced permeability for long service life in aggressive ground and exposure conditions.
Durable Blended-Cement Concrete
Lets producers exploit GGBS, fly ash and microsilica for lower heat, lower permeability and reduced carbon footprint while still hitting workability and early-strength targets.
Precast & Architectural Concrete
Supports self-compacting mixes that give clean, fully filled surfaces and sharp detail, improving finish quality and reducing finishing labour.
Frequently asked questions
Is Fosroc Auramix 403 a real product?
What type of admixture is Auramix 403?
What is the dosage of Auramix 403?
Can Auramix 403 be used with fly ash, GGBS and microsilica?
Does Auramix 403 meet Indian and international standards?
How is Auramix 403 different from Auramix 400?
How we position Fosroc Auramix 403
Auramix 403 sits in the mid-to-upper tier of Fosroc’s PCE superplasticiser range, between high-water-reduction grades like Auramix 400/450 and the workability-retention-focused options, making it a practical default for transit-mixed, pumped and self-compacting concrete. On a typical Indian project it pairs naturally with other Fosroc products Space Arc carries: Conplast SP430 where a more economical or naphthalene-based plasticiser is acceptable, a Fosroc curing compound such as Concure to protect the low-permeability surface it helps create, and an integral waterproofing admixture where water-tightness is specified, since a superplasticiser is not a waterproofer. Against the wider market, credible alternatives Indian specifiers will recognise include Sika’s ViscoCrete PCE superplasticisers, MBS/Master Builders Solutions MasterGlenium, Dr. Fixit’s admixture range and STP/Pidilite admixtures — all of which compete in the same SCC and high-performance pumped-concrete space. The honest position: Auramix 403 is a strong, specification-friendly PCE choice with proven Fosroc backing and IS 9103 / ASTM C494 alignment, but the right grade for your mix should be confirmed by trials, and where Fosroc’s published 403 datasheet does not state a specific numeric value, the figures shown here reflect the Auramix 4xx series band — ask Space Arc for the current product datasheet and a batch certificate before you lock a specification.
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