Fosroc Auracast HP
High-performance polycarboxylate ether superplasticiser engineered for ultra-high-strength and high-performance concrete from M60 up to M120 and beyond.
What is it?
A high-performance PCE (polycarboxylate ether) superplasticiser from Fosroc’s Auracast family, formulated for very high water reduction and long workability retention in high-strength concrete.
Where is it used?
High-rise columns and core walls, marine and coastal structures, metro and railway precast, self-compacting concrete, and any mix targeting M60–M120 grades at very low water-cementitious ratios.
Why use it?
It cuts mixing water by 25–40% versus a control mix, making w/cm ratios below 0.25 practical while keeping the concrete placeable with conventional site equipment.
How is it applied?
Dosed at 0.3–1.5% by weight of cementitious material, added with the mixing water at the batching plant, with the exact dosage fixed through project-specific trial mixes.
About Fosroc Auracast HP
Fosroc Auracast HP sits at the top end of the Auracast admixture range. It is built for the mixes that ordinary superplasticisers cannot serve: M80 to M120 concrete for tall-building cores, marine piles specified for 75–100 year design life, and dense impermeable concrete facing chemically aggressive service. At these grades, the binder content is high, the water-cementitious ratio drops below 0.30, and the mix becomes unworkable without a dispersant capable of 25–40% water reduction. Auracast HP delivers exactly that, and holds the workability long enough for real Indian site conditions — hot afternoons, long transit and staged pours included.
For contractors and RMC producers, the practical gain is that ultra-high-strength concrete stops demanding exotic equipment. Mixes in the M80–M120 band can be batched, transported and pumped with conventional plant. The admixture contains no chloride, so it is safe against reinforcement and prestressing steel, and it works alongside silica fume, GGBS and fly ash — the supplementary materials almost every high-performance mix in India now carries. Space Arc Engineering supplies Auracast HP across Delhi NCR and pan-India, with trial-mix support to lock the dosage before production pours.
The technical insight
Older SNF-based superplasticisers disperse cement mainly by electrostatic repulsion — the charged polymer coats cement grains and pushes them apart, but the effect fades within an hour as hydration products bury the polymer. PCE chemistry works differently. The polycarboxylate ether molecule is a comb polymer: a charged backbone grips the cement particle while long side chains project outward, physically preventing grains from re-flocculating. This steric hindrance is far more efficient per litre of admixture, which is what unlocks 25–40% water reduction. Less free water means fewer capillary pores, so the hardened paste is denser, stronger and dramatically less permeable — the real mechanism behind both M100-class strength and long design life. The side-chain architecture in Auracast HP is tuned for retention, so slump life extends beyond standard PCE grades rather than collapsing after batching.
Where it is used
- Ultra-high-strength concrete (M80–M120) for columns and core walls in high-rise buildings
- High-performance concrete for marine and coastal infrastructure exposed to chloride attack
- Very low w/cm concrete for bridges, flyovers and infrastructure specified for 75–100 year design life
- Dense, impermeable concrete for effluent plants and aggressive chemical environments
- Self-compacting concrete produced at very low water-binder ratios
- Precast high-strength elements for railways, metro viaducts and bridge segments
- Pumped high-grade concrete placed with conventional plant on tall structures
- Triple-blend mixes incorporating silica fume, GGBS or fly ash
Key advantages
- 25–40% water reduction versus control, making w/cm below 0.25 achievable in production
- Extended workability retention beyond standard PCE admixtures — suits long hauls and hot-weather concreting
- Enables M80–M120 concrete with conventional batching, transport and pumping equipment
- Fully compatible with silica fume, GGBS and fly ash blends
- Nil chloride content — safe for reinforced and prestressed concrete
- Denser, less permeable microstructure improves durability in marine and chemical exposure
- Wide 0.3–1.5% dosage window gives the mix designer room to optimise cost against performance
- Supports self-compacting concrete at water-binder ratios standard PCEs cannot reach
Limitations & considerations
- Dosage must be fixed by trial mixes — response varies with cement source, SCM type and ambient temperature
- Overdosing can cause excessive retardation, bleeding or segregation; disciplined batching control is essential
- Priced above SNF and standard PCE admixtures, so it is uneconomical for ordinary M20–M50 work
- Very low w/cm mixes are cohesive and sticky; pumping pressure and finishing methods need planning in advance
- Performance at low w/cm is sensitive to aggregate moisture variation — plants need reliable moisture correction
- Not a substitute for curing: high-binder mixes still demand early, continuous curing to control shrinkage
Selection & best practice
Start every project with laboratory trial mixes using the actual site cement, SCMs and aggregates, trialling dosages across the 0.3–1.5% by weight of cementitious material range until target flow, retention and strength are met. Add Auracast HP with the mixing water — never onto dry aggregate — and allow full mixing time before assessing workability. At w/cm ratios near 0.25, small errors matter: calibrate water meters, correct for aggregate moisture every shift, and never retemper with water on site; adjust workability only with additional admixture under the mix designer’s instruction. For pours with silica fume or GGBS, verify slump life at the actual ambient temperature expected during placement. Begin curing immediately after finishing, since high-binder mixes are prone to early-age shrinkage. Space Arc’s technical team assists with trial mixes and plant calibration across Delhi NCR and pan-India projects.
Specifications
| Chemistry | High-performance polycarboxylate ether (PCE) superplasticiser |
| Water reduction | 25–40% versus control mix |
| Dosage range | 0.3–1.5% by weight of cementitious material (fixed by trial mix) |
| Chloride content | Nil |
| Suitable concrete grades | M60 to M120 and above |
| Workability retention | Extended — significantly longer than SNF-based admixtures |
| SCM compatibility | Silica fume, GGBS, fly ash |
Industry use cases
High-Rise Construction
M80–M120 pumped concrete for columns, core walls and transfer girders in tall towers, where smaller high-strength sections free up carpet area on every floor.
Metro & Railways
Precast segments, U-girders and viaduct elements where high early quality, low permeability and consistent workability across long production runs are non-negotiable.
Marine & Ports
Piles, jetty decks and coastal structures where sub-0.30 w/cm concrete is the primary defence against chloride ingress and reinforcement corrosion.
Precast Plants
High-strength factory production and self-compacting mixes at very low water-binder ratios, cast with conventional plant equipment.
Industrial & Process Plants
Dense, impermeable concrete for effluent treatment structures and chemically aggressive environments where design life drives the specification.
Frequently asked questions
What dosage should I start with for an M80 mix?
How is Auracast HP different from Conplast SP430?
Can I use it with silica fume, fly ash or GGBS?
Will it delay setting of the concrete?
Is it safe for reinforced and prestressed concrete?
Is Auracast HP worth it for M30–M40 work?
How we position Fosroc Auracast HP
Auracast HP is the top tier of the Fosroc admixture line we stock. For standard high-performance work, Fosroc Auracast 200 covers everyday PCE requirements, Auramix 300 and Auramix 400 handle RMC workability retention, and Conplast SP430 remains the economical SNF choice for conventional grades. Pair it with Conplast WP90 where integral waterproofing is also specified. Space Arc also supplies comparable PCE ranges from Sika and Master Builders Solutions, so consultants can benchmark options before locking the specification.
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