About Fosroc Auramix 350 PQC

Fosroc Auramix 350 PQC is a ready-to-use liquid concrete admixture from the Fosroc Auramix superplasticiser family, engineered for one demanding job: producing strong, durable, long-life Pavement Quality Concrete (PQC). PQC is the rigid concrete used for highway slabs, service roads, toll plazas, airport aprons, container yards and industrial hard-standings, where the mix must be placed at very low slump, finished to tight tolerances and then carry heavy axle loads for decades. Achieving that combination demands a low water/cement ratio without sacrificing the workability needed for slip-form pavers or manual placing, and that is precisely the balance Auramix 350 PQC is built to strike.\n\nChemically, the product is a new-generation superplasticiser based on a polycarboxylic-ether (PCE) polymer with long lateral chains. Supplied as a light brown, water-soluble liquid, it works through an electrostatic dispersion mechanism: the polymer adsorbs onto cement grains and pushes them apart, breaking up cement flocs and freeing the trapped mixing water. The result is far better cement dispersion, a much larger surface area exposed to hydration, and a sharp drop in the water demand needed for a given workability. Mix designers can spend that gain in three ways: cut water to raise strength and cut permeability, raise slump/flow for easier placing, or trim cement content for a more economical mix.\n\nFor contractors, consultants and RMC producers in India, the practical appeal is consistency. Because PQC for roads is governed by MoRTH and IRC specifications and tested for flexural strength, the admixture must reliably hit low water/cement ratios while keeping the mix cohesive enough to resist segregation and bleeding during transport, paving and compaction. Auramix 350 PQC is positioned squarely for that workflow, and Space Arc Engineering supplies and supports it as an authorised Fosroc distributor and applicator across Delhi NCR and Pan-India.

The technical insight

The performance of Auramix 350 PQC comes from its long-lateral-chain PCE chemistry rather than older naphthalene or melamine sulphonate technology. Conventional sulphonated superplasticisers disperse cement mainly by electrostatic repulsion that decays quickly, which is why naphthalene-based mixes tend to lose slump fast. The PCE backbone in Auramix 350 PQC carries comb-like side chains that add steric (physical) hindrance on top of electrostatic charge, keeping cement particles separated for longer and giving the extended workability retention that PQC paving needs between batching, haulage and laydown. This is what allows a genuinely low water/cement mix to remain placeable.\n\nThree numbers anchor its behaviour on site. The dosage window of 0.3-1.3% by weight of total cement or binder is wide, so the same product can serve an economy mix and a high-flexural-strength PQC mix simply by adjusting addition rate against trial data. The volumetric mass of 1.08 +/- 0.02 kg/litre at 25 degrees C lets batching plants convert between mass and volume dispensing accurately. And the nil chloride content (to IS 456) is what makes it safe in reinforced and prestressed sections and compatible with sulphate-resisting cement and marine aggregates. The trade-off to manage is over-dosing: because PCE is a powerful retarder at high addition rates, exceeding the established dosage can delay set and trigger segregation, so dosage must always be fixed by laboratory and batch trials, not assumed.

Where it is used

• Pavement Quality Concrete (PQC) for rigid highway and expressway slabs
• Service roads, toll plazas, parking aprons and industrial hard-standings
• Airport runways, taxiways and aprons requiring high flexural strength
• Container freight yards, ports and heavy-duty pavement decks
• Ready-mix concrete (RMC) production of low water/cement, low-slump mixes
• High-strength and high-durability structural concrete where low permeability is specified
• Precast concrete elements needing high early strength for faster de-moulding
• Reinforced and prestressed concrete where a chloride-free admixture is mandatory

Key advantages

• Improved workability for easier, quicker placing and compaction at low slump
• High early strength development, valuable for precast and fast-track paving
• Substantial water reduction giving denser, low-permeability, more durable concrete
• Higher cohesion that minimises segregation and bleeding and aids pumping
• Long workability retention from long-lateral-chain PCE chemistry
• Completely chloride-free, safe in prestressed concrete and with sulphate-resisting cements and marine aggregates
• Wide dosage range (0.3-1.3%) lets one product serve economy and high-performance PQC mixes
• Complies with IS 9103:1999 and ASTM C494 as a water-reducing admixture

Limitations & considerations

• Over-dosage beyond the recommended range can delay setting and cause segregation
• Optimum dosage must be established by laboratory and batch trials, not assumed, as it varies with cement, aggregates and mix design
• Performance depends on mix proportions and materials; results vary between sources of cement and supplementary cementitious materials
• Being highly water-reducing, it is intended for designed mixes, not as a fix for poorly proportioned concrete
• Shelf life is 12 months and only when stored between 2 and 50 degrees C; freezing or excessive heat can affect the product
• A liquid admixture only; it provides no curing, mould-release or waterproofing function on its own
• Specific gravity, pH and chloride values can vary slightly for customer-specific configurations, so the issued MTC should be referenced for QC

Selection & best practice

Specifications

Industry use cases

How we position Fosroc Auramix 350 PQC

Within the Fosroc range, Auramix 350 PQC is the pavement-focused member of the Auramix PCE superplasticiser family, sitting alongside general-purpose grades such as Fosroc Auramix 350, Auramix 350 DIS and Auramix 400; where those serve broad RMC and structural needs, the PQC variant is tuned for the low-slump, high-flexural-strength road and infrastructure mixes governed by MoRTH and IRC. It is typically specified together with complementary Fosroc products on a paving project, such as a curing compound from the Concure range to control early moisture loss on fresh slabs and a release agent from the Reebol range for formwork. Among competing high-range water reducers available in India, credible alternatives include Sika ViscoCrete and Sikament PCE-based superplasticisers, the Master Builders Solutions (MBS, formerly BASF) MasterGlenium range, and PCE admixtures from STP (Structural Waterproofing) and Dr. Fixit’s admixture line. The right choice on any given pour comes down to trial performance with the project’s specific cement and aggregates, workability-retention needs against the haul-and-lay cycle, and commercial terms. As an authorised Fosroc distributor and applicator covering Delhi NCR and Pan-India, Space Arc Engineering supplies Auramix 350 PQC with mix-design and on-site dosage-trial support so contractors and consultants can validate it against their PQC specification before committing to a full production pour.

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