Fosroc Auramix 240
A high-performance, synthetic-polymer water-reducing admixture engineered for ready-mixed concrete and civil works that demand strong water reduction, extended slump retention and a denser, more impermeable finish.
What is it?
A new-generation, synthetic-polymer-based plasticiser and water-reducing admixture from Fosroc’s Auramix range, designed to disperse cement particles and cut mixing water without sacrificing workability.
Where is it used?
Ready-mixed concrete (RMC) plants, civil engineering works, infrastructure pours and general structural concrete where consistent workability and durability matter, including hot-weather placements.
Why use it?
It reduces water demand by roughly 15-20%, which raises strength and density, lowers permeability, improves surface appearance and keeps concrete workable longer than conventional plasticisers.
How is it applied?
Dosed by weight of cement (typically 0.3-1.1% / 0.3-1.1 litres per 100 kg) and added to the mixing water or directly to wet concrete at the batching plant; trial mixes confirm the optimum dosage.
About Fosroc Auramix 240
Fosroc Auramix 240 belongs to the Auramix family of concrete admixtures, sitting in the plasticiser / water-reducer tier of the range. Unlike older lignosulfonate-based plasticisers, Auramix 240 is built on a new generation of synthetic polymer molecules that wrap around and disperse cement grains far more efficiently. The practical result is a high water-reduction admixture that lets a producer remove a meaningful proportion of mixing water while still delivering the slump the placing crew needs.
For an RMC producer or a contractor batching concrete on a large civil project, water is the enemy of durability: every extra litre that is not chemically needed for hydration ends up as capillary porosity, lower strength and higher permeability. Auramix 240 attacks that problem directly. By cutting water demand by around 15-20% at working dosages, it allows the water-cement ratio to be lowered at constant workability, or workability to be increased at constant water-cement ratio – the producer chooses which lever to pull based on the mix design and the job.
The product is positioned by Fosroc as a multifunctional, high-end plasticiser for ready-mixed concrete and civil works. Two characteristics make it attractive in Indian conditions. First, it holds workability longer than conventional plasticisers, which matters when concrete has to travel from plant to a congested urban or infrastructure site in heavy traffic and high ambient temperatures. Second, the new-generation chemistry improves the compactness and surface appearance of the hardened concrete and imparts water-repellent character, reducing the water penetration that drives reinforcement corrosion and freeze-thaw or chloride damage over a structure’s life.
Auramix 240 is supplied as a liquid that is added at the batching stage. It is a chloride-free admixture (water-soluble chloride content is held at or below 0.10%), so it is suitable for reinforced and prestressed concrete where chloride ingress must be controlled. It is formulated to comply with EN 934-2 (Table 2) as a water-reducing / plasticising admixture, the European harmonised standard for concrete admixtures – the functional equivalent in Indian practice being IS 9103 and ASTM C494 Type A / Type D categories.
The technical insight
The defining feature of Auramix 240 is the chemistry of dispersion. Conventional plasticisers (lignosulfonates, naphthalene or melamine sulfonates) work largely by electrostatic repulsion – they charge the cement grains so they push apart. Newer synthetic-polymer admixtures add a steric (physical spacer) mechanism: long polymer side-chains keep the grains separated even as the electrostatic charge dissipates. That combination is why Auramix 240 can both deliver a strong 15-20% water reduction and hold the slump longer in the truck, even in hot weather where many plasticisers flash-set or lose workability quickly. For the structural engineer, the lower achievable water-cement ratio at a given workability translates into higher 28-day compressive strength and, just as importantly, a denser pore structure that cuts water and chloride penetration – the single biggest driver of long-term durability in Indian RCC. The chloride-free formulation (Cl- content kept at or below 0.10%) and controlled alkali content (a maximum near 5% Na2O equivalent by mass) mean the admixture itself does not introduce corrosion-promoting ions or aggravate alkali-silica reactivity. Compatibility is a practical caveat worth flagging on site: Auramix 240 can be combined with other Fosroc admixtures in the same mix, but each admixture must be dispensed separately into the concrete rather than pre-blended, to avoid interaction in the concentrate.
Where it is used
- Ready-mixed concrete (RMC) production where consistent workability and water reduction are required across multiple grades
- Civil engineering and infrastructure concrete – foundations, rafts, retaining structures, pavements and general structural pours
- Concrete that must retain workability during long haul times in heavy traffic or high ambient temperatures
- Durable RCC where reduced permeability and water penetration are specified to protect reinforcement
- Mass and structural concrete where improved surface appearance and compactness are valued
- Hot-weather concreting where extended slump retention reduces the risk of cold joints and re-tempering
Key advantages
- Strong water reduction of approximately 15-20% at working dosages, raising strength and density at constant workability
- Extended workability/slump retention versus conventional plasticisers, beneficial for long transit and hot climates
- New-generation synthetic-polymer chemistry combining electrostatic and steric dispersion of cement particles
- Improved compactness, surface appearance and water-repellent character of the hardened concrete
- Reduced permeability and water penetration, supporting long-term durability and corrosion protection of rebar
- Chloride-free formulation (Cl- content at or below 0.10%), suitable for reinforced and prestressed concrete
- Compliant with EN 934-2 Table 2 as a water-reducing/plasticising admixture
- Long 12-month shelf life and non-flammable, easing storage and logistics at the plant
Limitations & considerations
- Optimum dosage must be established by trial mixes – overdosing can cause retardation, segregation or bleeding
- When combined with other admixtures, each must be dispensed separately into the concrete, not pre-mixed in the concentrate
- As a plasticiser/water reducer it does not provide the very high water reduction of a full superplasticiser (e.g. Auramix 300/400) needed for high-strength or self-compacting concrete
- Primarily catalogued for the European and Latin American Fosroc markets; Indian buyers should confirm regional availability, the India-specific datasheet and IS 9103 / ASTM C494 classification with the supplier
- Performance depends on cement type, aggregate, temperature and mix design – results vary and should be validated on the actual job materials
- Liquid admixture that must be protected from freezing and stored within the specified 2-40 degree C temperature band
Selection & best practice
Always begin with site-specific trial mixes using the actual cement, aggregates and ambient conditions of the project, starting near the lower end of the 0.3-1.1% (per 100 kg cement) dosage band and adjusting upward to hit the target water reduction and slump. Add Auramix 240 to the gauging water or to the wet concrete at the plant – never to dry cement – and, if other admixtures are used, dispense each one separately. Keep the product in its original sealed containers in a dry, shaded store between 2 and 40 degrees C, protect it from freezing, and use within its 12-month shelf life. For high-strength, pumpable or self-compacting concrete, evaluate a polycarbonate-ether superplasticiser from the same Auramix family instead of, or in combination with, Auramix 240. Confirm the current regional technical data sheet and standard compliance with Space Arc Engineering before specifying.
Specifications
| Product type | New-generation synthetic-polymer plasticiser / water-reducing admixture |
| Primary function | Water reduction and cement-particle dispersion for ready-mixed concrete |
| Form | Liquid admixture, added at batching |
| Standard compliance | EN 934-2:2010 Table 2 (water reducer/plasticiser); IS 9103 / ASTM C494 equivalent categories |
| Typical dosage | 0.3-1.1% (0.3-1.1 litres per 100 kg) by weight of cement |
| Water reduction | Approximately 15-20% depending on dosage |
| Water-soluble chloride (Cl-) | At or below 0.10% |
| Alkali content (Na2O equivalent) | Maximum approximately 5% by mass |
| Shelf life | 12 months in original sealed containers |
| Storage temperature | 2 degrees C to 40 degrees C, protect from freezing |
| Flammability | Non-flammable |
| Compatibility | Compatible with other Fosroc admixtures; dispense each separately into the mix |
Industry use cases
Ready-Mixed Concrete (RMC)
Batching plants use Auramix 240 across multiple concrete grades to cut mixing water by 15-20%, hold slump through long deliveries, and supply denser, more durable concrete without raising cement content.
Infrastructure & Civil Works
Foundations, rafts, retaining walls, pavements and bridge substructures benefit from the lower water-cement ratio and reduced permeability, improving load-bearing capacity and service life of structural RCC.
Hot-Weather Concreting
On Indian summer pours and in arid regions, the extended workability retention reduces the risk of cold joints, re-tempering and slump loss between plant and placement.
Durable & Marine-Adjacent Structures
Where chloride ingress and water penetration threaten reinforcement, the chloride-free formulation and water-repellent, low-permeability concrete it produces help protect rebar over the long term.
Frequently asked questions
What exactly is Fosroc Auramix 240?
How much water does Auramix 240 reduce?
What is the recommended dosage?
Is Auramix 240 a superplasticiser?
Is it suitable for reinforced concrete?
Is Auramix 240 available in India through Space Arc Engineering?
How we position Fosroc Auramix 240
Within Fosroc’s Auramix range, Auramix 240 occupies the high-performance plasticiser / water-reducer slot – a step above basic plasticisers like Auramix 200/201 for producers who want stronger 15-20% water reduction and longer slump retention, but below the polycarboxylate-ether superplasticisers (Auramix 300, Auramix 350, Auramix 400) reserved for high-strength, pumpable and self-compacting concrete. Buyers should also note related Fosroc admixtures such as the Conplast range for general water-reducing and retarding duties. Against competitors, the closest equivalents are Sika’s plasticiser/water-reducer lines (e.g. Sika Plastiment and Sikament grades), the BASF/Master Builders Solutions MasterPozzolith and MasterPolyheed plasticisers, and STP’s admixture range; Dr. Fixit is better known for waterproofing chemicals than for RMC plasticisers, so it is a less direct alternative in this category. For most Indian RMC and civil-works applications, the practical choice between Auramix 240 and these alternatives comes down to verified trial-mix performance on the actual cement and aggregate, regional availability, and technical support – all of which Space Arc Engineering can arrange as an authorised Fosroc distributor and applicator. Note: specific gravity, exact compressive-strength figures and the India-specific datasheet were not independently verified at the time of writing and should be confirmed against the current regional TDS.
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