About Fosroc Auramix 300

Fosroc Auramix 300 is an advanced, low-viscosity retarding superplasticiser based on polycarboxylic ether (PCE) technology. Fosroc India’s Technical Data Sheet describes it as “a unique combination of the latest generation superplasticisers, based on a polycarboxylic ether polymer with long lateral chains.” Those lateral chains drive a steric dispersion mechanism that separates cement particles efficiently, releasing trapped water and allowing high-performance concrete to be produced at reduced water content without sacrificing cohesion.

As an authorised Fosroc distributor and applicator serving Delhi NCR and Pan-India, Space Arc Engineering positions Auramix 300 specifically where its retarding character is an advantage. The product is engineered for mass raft foundations, pumped concrete, and concrete that must hold workability over long haul, placement and finishing windows. In Indian conditions, where ambient temperatures and long transit times accelerate slump loss, the combined plasticising-and-retarding action helps maintain placeability while moderating the rate of heat development in large, thick sections.

Auramix 300 carries a chloride content of Nil to IS:456 and a typical alkali content of less than 1.5 g Na2O equivalent per litre, making it compatible with reinforced and structural concrete design requirements. It complies with IS 9103-1999 (2007) and meets ASTM C 494 both as a Type F (high-range water-reducing) and a Type G (water-reducing and retarding) admixture, depending on the dosage selected — a distinction that matters because the retarding behaviour is core to the product’s intended use. Where a non-retarding high-range water reducer is preferred, the wider Fosroc Auramix and Conplast PCE families, or comparable PCE admixtures such as BASF MasterGlenium and Sika ViscoCrete, can be specified alongside it.

The technical insight

The performance of Auramix 300 comes from its polycarboxylic ether backbone carrying long lateral (comb) chains. Unlike older sulphonated naphthalene formaldehyde (SNF) plasticisers that disperse cement mainly by electrostatic repulsion, the PCE comb structure adsorbs onto cement grains and creates steric (physical) separation, which keeps particles dispersed for longer and supports extended workability retention at a lower viscosity. Fosroc classes it as an “advanced low-viscosity retarding superplasticiser, based on polycarboxylic technology.” The retarding action slows early hydration, which is the property leveraged for mass concrete: by spreading heat evolution over a longer period, peak core temperatures and thermal gradients in large raft pours are easier to manage. Because the same chemistry can satisfy either ASTM C 494 Type F or Type G depending on dose, the admixture should always be optimised through laboratory and site trial mixes with the project’s specific cement and supplementary cementitious materials.

Where it is used

• Mass raft foundations requiring controlled heat of hydration
• Pumped concrete needing low-viscosity, free-flowing mixes
• Concrete requiring long workability retention during transit and placement
• High-performance concrete at reduced water content
• Ready-mixed concrete (RMC) supplied over extended haul distances
• Large structural pours where extended setting aids placement and finishing

Key advantages

• Polycarboxylic ether (PCE) chemistry delivers efficient water reduction at low dosage
• Retarding action extends workability and helps control heat of hydration in mass concrete
• Low-viscosity formulation supports easy pumping and free flow
• Chloride content Nil to IS:456, suitable for reinforced concrete
• Low alkali content, typically under 1.5 g Na2O equivalent per litre
• Complies with IS 9103 and ASTM C 494 Type F and Type G

Limitations & considerations

• Optimum dosage must be established by trial mix; over-dosing can cause excessive retardation or bleeding
• Retarding character means it is not the first choice where rapid early strength gain is required
• PCE admixtures can be sensitive to cement chemistry and clay content in aggregates
• Performance figures and water reduction depend on mix design; values should be verified against the current Fosroc TDS for the project
• Compatibility with other admixtures should be checked before combined use

Selection & best practice

Specifications

Industry use cases

How we position Fosroc Auramix 300

Lead-with-Fosroc retarding PCE superplasticiser, positioned by Space Arc Engineering for mass raft foundations, pumped concrete and long workability retention. Differentiated from non-retarding high-range water reducers in the wider Fosroc Auramix/Conplast range and from comparable PCE products such as BASF MasterGlenium and Sika ViscoCrete by its deliberate retarding action and heat-of-hydration control.

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