Fosroc Auramix 375
High-power water-reducing superplasticiser engineered for low-viscosity, high-strength concrete and wet-process shotcrete.
What is it?
A high-range water-reducing (HRWR) superplasticising admixture from Fosroc’s Auramix family, formulated to make very fluid, low-viscosity concrete while cutting the water content needed to reach a given workability.
Where is it used?
Ready-mixed and site-batched structural concrete, high-strength mixes, concrete made with difficult or granitic aggregates, and wet-process (wet-mix) sprayed concrete / shotcrete.
Why use it?
It lets you reduce water without losing flow, which raises early and final compressive strength, improves cohesion and pumpability, and produces flowable concrete that can often be placed with little or no vibration.
How is it applied?
Dispensed as a liquid into the mixing water or added to the wet concrete at the batching plant or mixer at a controlled dosage per 100 kg of cementitious material, then mixed to a uniform consistency before placing.
About Fosroc Auramix 375
Fosroc Auramix 375 is a liquid superplasticising (high-range water-reducing) concrete admixture that sits within Fosroc’s Auramix admixture range, alongside familiar grades such as Auramix 300, 350 and 400. According to Fosroc’s official product literature, Auramix 375 is positioned as a high-power water-reducing additive specifically designed to produce low-viscosity concrete. In plain terms, it is the chemical you add to a concrete mix when you want the mix to flow easily and place without fuss, yet still gain strength quickly and reach a high final strength.
The defining characteristic Fosroc highlights for Auramix 375 is its ability to minimise the cohesive, “sticky” behaviour that some mixes develop and to reduce the internal friction caused by flaky or lamellar aggregate particles. That makes it well suited to concrete produced with all aggregate types, and Fosroc calls out granitic aggregates in particular, the kind of hard, angular crushed stone common across many Indian quarry sources. Where a plain mix with such aggregate might be harsh, draggy and hard to pump, Auramix 375 helps the same materials behave as a smooth, mobile, robust concrete.
For contractors, consultants and ready-mix producers in India, the practical appeal is twofold. First, the high water reduction allows a lower water-to-cement ratio at a target slump, which directly translates into higher early-age and 28-day compressive strengths and a denser, more durable matrix. Second, the admixture supports the production of extremely fluid concrete that, per Fosroc, can be placed without vibration, useful for congested reinforcement, deep sections and complex formwork where mechanical compaction is awkward. Fosroc also identifies wet-process shotcrete (wet-mix sprayed concrete) as an application, where consistent rheology and reduced rebound matter for tunnel linings, slope stabilisation and repair overlays.
Space Arc Engineering supplies Fosroc Auramix 375 and the wider Fosroc admixture range to projects across Delhi NCR and Pan-India, with technical support on dosage trials, mix optimisation and compatibility checks. Because admixture performance is sensitive to cement chemistry, supplementary cementitious materials and local aggregates, we always recommend confirming the exact grade and dosage for your mix against the current Fosroc Technical Data Sheet for your region.
The technical insight
Auramix 375 works on the same physical principle that defines all modern superplasticisers: it disperses cement particles that would otherwise clump together, freeing the trapped mixing water so it lubricates the mix instead of being locked inside flocs. The “high-power water reduction” Fosroc claims for this grade means a relatively large drop in water demand at equal workability, which is the lever that raises strength and durability. The product’s distinguishing trait, low-viscosity output, matters because plasticised concrete can still be viscous and sticky; a low-viscosity mix flows and pumps more readily, fills formwork cleanly and reduces the effort needed for placing and finishing. Fosroc specifically attributes this to Auramix 375’s action in countering aggregate-driven friction (notably with granitic stone) and reducing over-cohesion, which is what keeps a high-fluidity mix from segregating into a soupy, bleeding paste. The result Fosroc describes is a stable, robust concrete with minimal slump fluctuation, plus improved mechanical resistance at both early and final ages. Exact numerical properties, specific gravity, chloride content, recommended dosage band, air entrainment and standards classification, are published on the country-specific Fosroc Technical Data Sheet and Safety Data Sheet, and should be read for the territory of supply before specification. Within the Auramix family these grades are typically chloride-free and dosed as a percentage of cementitious content; the Auramix 375 TDS for your region governs the precise figures.
Where it is used
- High-strength structural concrete where a low water-cement ratio is required at workable slump
- Ready-mixed concrete needing reliable slump and pumpability over the haul and placing window
- Concrete made with hard, angular or granitic crushed aggregates that would otherwise be harsh or draggy
- Highly fluid, near-self-levelling concrete placed with little or no vibration in congested or deep sections
- Wet-process (wet-mix) sprayed concrete / shotcrete for tunnel linings, slope stabilisation and repair
- Pumped concrete for tall pours, rafts and transfer elements where flow and cohesion must be balanced
- Precast and site concrete where high early strength supports faster de-moulding or load application
Key advantages
- High water-reducing capacity that lowers the water-cement ratio and lifts both early-age and final compressive strength
- Produces low-viscosity, free-flowing concrete that is easier to place, pump and finish
- Counteracts the friction and harshness of lamellar and granitic aggregates for smoother, more workable mixes
- Supports extremely fluid concrete that can be placed without vibration in difficult formwork
- Improves cohesion and stability, helping resist segregation and minimise slump fluctuation
- Suitable for use with all aggregate types, giving mix-design flexibility across varied Indian aggregate sources
- Enables denser, lower-permeability concrete that improves long-term durability
- Liquid form is straightforward to dispense and disperse through the batching water
Limitations & considerations
- Exact dosage, specific gravity and standards classification must be taken from the current region-specific Fosroc TDS, not assumed
- Overdosing can cause excessive flow, retardation, bleeding or segregation; trial mixes are essential
- Performance varies with cement type, SCMs (fly ash, GGBS, silica fume), aggregate and ambient temperature, so compatibility trials are advised
- As a high-fluidity admixture it demands a well-proportioned, cohesive base mix; a poorly graded mix may segregate
- Not an air-entraining agent or a freeze-thaw solution on its own; pair with the correct product where durability classes require it
- Being water-based it should be protected from freezing and stored within the manufacturer’s temperature and shelf-life limits
- Results from one Auramix grade do not transfer directly to another (300/350/375/400) without re-trialling
Selection & best practice
Always begin with laboratory and site trial mixes using your actual cement, SCMs and aggregates to fix the optimum dosage and confirm slump, slump retention and strength before production. Add Auramix 375 to the mixing water or to the wetted mix rather than onto dry materials, and allow adequate mixing time for full dispersion. Start near the lower end of the dosage band indicated on the current Fosroc TDS and adjust upward in small steps, watching for any sign of bleeding or segregation. Keep the water-cement ratio controlled, increasing dosage is not a substitute for added water, and account for any free moisture in aggregates. Where high fluidity is the goal, ensure the base mix is cohesive and well graded so the concrete stays stable. Store containers sealed, out of direct sun and protected from frost, and use within the stated shelf life. Verify chloride status and standards compliance against the region-specific datasheet when specifying for reinforced or prestressed work, and consult Space Arc Engineering’s technical team for mix-design support.
Specifications
| Product type | High-range water-reducing (HRWR) superplasticising admixture |
| Primary function | High-power water reduction to produce low-viscosity, high-strength concrete |
| Form | Liquid admixture, dispensed into the mixing water |
| Key benefit | Reduces aggregate friction and cohesion; suits all aggregates, including granitic |
| Notable application | Structural / high-strength concrete and wet-process shotcrete |
| Placing characteristic | Enables highly fluid concrete placeable with little or no vibration |
| Strength effect | Improved early-age and final compressive strength via lower w/c ratio |
| Specific gravity / density | Refer to current region-specific Fosroc Auramix 375 TDS |
| Chloride content | Refer to TDS (Auramix grades are typically chloride-free) |
| Recommended dosage | Refer to TDS; established by trial mix per cementitious content |
| Standards | Per region-specific TDS (e.g. EN 934-2 in Europe; verify locally) |
| Pack size | As listed on the regional Fosroc datasheet / price list |
| Storage & shelf life | Store sealed, protect from frost; use within manufacturer’s stated shelf life |
Industry use cases
Ready-Mix Concrete (RMC)
Producers use Auramix 375 to hold target slump and pumpability while cutting water, raising strength grades and improving the placeability of mixes batched with local granitic aggregates.
Tunnelling & Underground
As a wet-process shotcrete admixture it supports consistent sprayed-concrete rheology for tunnel linings, ground support and slope stabilisation, helping control rebound and build.
High-Rise & Infrastructure
High water reduction and low viscosity make it suited to pumped, high-strength concrete for columns, transfer slabs, rafts and bridge elements where flow and density are critical.
Precast & Prefab
Improved early strength from a lower water-cement ratio helps speed de-moulding cycles while the fluid, low-viscosity mix fills intricate moulds and congested reinforcement cleanly.
Repair & Rehabilitation
Used in sprayed and placed structural repair concrete where dense, cohesive, vibration-free placement is needed around existing steel and in confined sections.
Frequently asked questions
Is Fosroc Auramix 375 a real product?
What type of admixture is Auramix 375?
What makes Auramix 375 different from other Auramix grades?
What dosage of Auramix 375 should I use?
Can Auramix 375 be used for shotcrete and pumped concrete?
Does Space Arc Engineering supply Auramix 375 in India?
How we position Fosroc Auramix 375
Auramix 375 belongs to Fosroc’s Auramix superplasticiser family and is best understood alongside its siblings: Auramix 300, 350 and 400 are widely specified high-performance superplasticisers in India, while 375 is positioned for low-viscosity, high-power water reduction and difficult aggregates. Within the broader Fosroc catalogue it complements the long-established Conplast superplasticiser range (such as Conplast SP430), giving specifiers a choice of admixture chemistries for different workability-retention and strength needs. Where a project is standardising on a particular admixture, it is worth comparing Auramix 375 against credible alternatives from other manufacturers, for example Sika (Sika ViscoCrete / Sikament high-range water reducers), Master Builders Solutions (MasterGlenium / the former Glenium PCE range), and locally strong brands such as Dr. Fixit (Pidilite) and STP for general construction-chemical supply. For straightforward water reduction the choice often comes down to cement and aggregate compatibility, slump-retention needs and supply support; for low-viscosity, granitic-aggregate or wet-shotcrete mixes, Auramix 375’s specific positioning is a strong fit. Space Arc Engineering, as a Fosroc distributor and applicator, can run comparative trial mixes and recommend the optimal grade rather than defaulting to a single product, ensuring the admixture chosen genuinely matches the mix design, exposure class and placing method.
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