Fosroc Auramix 388
A new-generation polycarboxylic-ether superplasticiser that holds high slump for around two hours, letting you place self-compacting, free-flowing concrete over long transport distances without sacrificing strength or set time.
What is it?
A latest-generation, high-activity polycarboxylic-ether (PCE) based water-reducing superplasticising admixture from Fosroc, designed specifically for extended workability (around 2 hours) and high slump without delaying the concrete’s set.
Where is it used?
Ready-mixed concrete batched far from site, self-compacting (SCC) and self-levelling concrete, heated/radiant floor slabs, precast and high-performance structural concrete where long open time and free flow are critical.
Why use it?
It lets concrete stay highly workable through long haul times and hot Indian weather, reduces mixing water for higher strength and lower permeability, and improves placement and surface finish while cutting compaction labour.
How is it applied?
Dosed at the batching plant into the mixing water or onto wet concrete, either alone or combined with a complementary water reducer for slump-retention; trial mixes confirm dosage, then it is added per the project mix design and Fosroc TDS.
About Fosroc Auramix 388
Fosroc Auramix 388 is a high-activity water-reducing admixture, more commonly called a high-range superplasticiser, from Fosroc’s Auramix concrete-admixture family. Like the rest of the modern Auramix range, it is built on polycarboxylic-ether (PCE) polymer chemistry, where long side-chain molecules wrap around cement grains and push them apart through combined electrostatic and steric (physical) repulsion. The practical result is that the same concrete can be made far more fluid at a given water content, or the same workability can be achieved with substantially less water. What sets Auramix 388 apart within the range is its emphasis on extended workability: Fosroc positions it as a next-generation superplasticiser able to hold a high slump for roughly two hours without retarding the set of the concrete. For Indian contractors and ready-mix producers, that combination, long open time without a delayed set, directly addresses two everyday problems: concrete losing slump during long road journeys in heavy traffic, and slump loss accelerated by high ambient temperatures across most of the country for much of the year. Because the admixture maintains flow rather than relying on extra water, the placed concrete keeps a low water-cement ratio, which is what ultimately drives strength, density and durability. Fosroc explicitly notes that Auramix 388 improves both early-age and final mechanical strengths, supports the production of stable, homogeneous, highly workable concrete suitable for self-compacting and self-levelling applications, and can be used in combination with other water-reducing admixtures to fine-tune slump retention over time. It is a site- and plant-grade product aimed at performance concrete rather than a curing compound, mould-release agent or repair material. Space Arc Engineering, an authorised Fosroc distributor and applicator serving Delhi NCR and Pan-India, supplies Auramix 388 alongside the wider Fosroc admixture, waterproofing and concrete-repair portfolio, with technical support to match the right admixture and dosage to each mix design.
The technical insight
The defining technical behaviour of Auramix 388 is decoupling workability retention from set retardation. With many older superplasticisers, the only way to hold slump for two hours was to load in a retarder, which pushed back setting times, slowed strength gain and risked plastic problems in cool conditions. PCE chemistry of the type used across the Auramix range allows the polymer to release its dispersing effect in a more controlled, time-staggered way, so the mix stays fluid as it travels and waits, then sets and gains strength on a normal schedule once placed. The high water-reduction capacity is the second lever: by dispersing cement so efficiently, Auramix 388 lets you cut mixing water while keeping a target slump, which lowers the water-cement ratio. A lower w/c ratio is the single most important factor behind higher compressive strength, reduced permeability and better resistance to carbonation and chloride ingress, the durability properties that matter for reinforced concrete in aggressive Indian exposure conditions. Because the resulting concrete is stable and cohesive rather than just wet, it resists segregation and bleeding even at high flow, which is exactly what self-compacting and self-levelling concrete require. The practical engineering caveat is that PCE superplasticisers are dosage-sensitive and interact strongly with cement chemistry, fly ash/GGBS content, fines and aggregate grading, so the correct dosage is established by trial mix and confirmed against the current Fosroc Technical Data Sheet rather than carried over from a different mix.
Where it is used
- Long-haul ready-mixed concrete that must retain high slump during extended transit
- Self-compacting concrete (SCC) for congested reinforcement and complex formwork
- Self-levelling concrete and heated/radiant floor screeds requiring free flow
- High-performance and high-strength structural concrete with low water-cement ratio
- Concrete placed in hot weather where rapid slump loss is a problem
- Precast and pumped concrete needing stable, homogeneous, cohesive flow
Key advantages
- Holds high slump for around two hours without retarding the concrete’s set
- High water-reduction capacity, enabling lower water-cement ratio and higher strength
- Improves both early-age and final compressive strengths
- Produces stable, highly homogeneous concrete that resists segregation and bleeding
- Suitable for self-compacting and self-levelling concrete with excellent flow
- Improves placement, finish and pumpability while reducing compaction labour and costs
- Can be combined with other water-reducing admixtures to tailor slump retention
- Lower permeability and improved durability follow from the reduced water content
Limitations & considerations
- It is a superplasticiser, not a curing compound, mould-release agent or repair product; conventional curing is still required
- PCE chemistry is dosage-sensitive and overdosing can cause segregation, bleeding or excessive retardation
- Performance varies with cement type, SCM content (fly ash/GGBS), fines and aggregate grading, so trial mixes are essential
- Slump-retention and dosage behaviour should be confirmed against the current country-specific Fosroc TDS, especially as it is positioned for the Spanish/Latin American market
- Not interchangeable with other Auramix grades without a fresh mix design
- Like all admixtures it must be stored within recommended temperature limits and protected from freezing
Selection & best practice
Always start from a laboratory or plant trial mix using the actual project cement, supplementary cementitious materials, aggregates and target slump, then dose Auramix 388 strictly within the range and method given on the current Fosroc Technical Data Sheet for your region. Add it to the mixing water or to already-wetted concrete (never to dry cement), and where very long slump retention is needed, combine it with a complementary water reducer rather than overdosing the superplasticiser. For self-compacting concrete, verify flow, passing ability and segregation resistance with slump-flow and related tests before pour day, and keep the water-cement ratio fixed so the gain comes from dispersion, not added water. Maintain normal curing practice once placed, and verify the latest TDS and Safety Data Sheet through your authorised distributor, Space Arc Engineering, before each project.
Specifications
| Product type | High-activity water-reducing admixture / high-range superplasticiser |
| Polymer chemistry | Polycarboxylic ether (PCE) based, consistent with the Auramix range |
| Key performance | Extended workability of approximately 2 hours at high slump |
| Effect on set | No setting retardation (per Fosroc product description) |
| Water reduction | High water-reduction capacity (high-range) |
| Strength effect | Improves both early-age and final mechanical strengths |
| Concrete suitability | Self-compacting and self-levelling concrete; stable, homogeneous mixes |
| Combinability | Can be used with other water-reducing admixtures for slump retention |
| Category | Concrete admixtures (Fosroc Auramix family) |
| Specific gravity / dosage / chloride content | Refer to current country-specific Fosroc TDS (not published on open product page; confirm via Space Arc Engineering) |
Industry use cases
Ready-Mixed Concrete (RMC)
Producers batching for sites across congested Delhi NCR or long pan-India hauls use Auramix 388 to keep concrete flowing on arrival despite traffic delays and heat, avoiding the temptation to re-temper with water that would weaken the mix.
Self-Compacting Concrete
Contractors casting heavily reinforced columns, raft foundations or architectural elements rely on its stable high flow to fill complex formwork fully without vibration, reducing labour and honeycombing risk.
Industrial & Heated Floors
Self-levelling and radiant/heated floor slabs benefit from the free-flowing, homogeneous concrete it produces, giving a flatter surface with less manual screeding.
High-Performance Structural Concrete
Consultants and engineers specifying low water-cement-ratio, durable concrete for high-rise and infrastructure work use its water reduction to hit strength and permeability targets.
Precast & Pumped Concrete
Precast yards and pumping contractors use the cohesive, segregation-resistant flow for clean demoulding, sharp finishes and reliable long-distance pumping.
Frequently asked questions
Is Fosroc Auramix 388 a real product?
What does Auramix 388 actually do?
How is Auramix 388 different from other Auramix grades like 300, 400 or 500?
What dosage should I use?
Can Auramix 388 be used for self-compacting concrete in India?
Does Auramix 388 replace curing or waterproofing products?
How we position Fosroc Auramix 388
Within the Fosroc Auramix line-up, Auramix 388 sits among the high-range PCE superplasticisers and is the natural choice when extended workability and slump retention matter most, complementing grades such as Auramix 300 and Auramix 300 Plus (high-performance, durability-focused) and Auramix 400/500 (high and ultra-high strength). Where viscosity control is needed for SCC, it pairs logically with a viscosity-modifying agent like Fosroc Auramix V200, and on real projects it is typically specified alongside Fosroc curing compounds, Conplast water-reducers and the Nitobond/Renderoc repair and bonding systems that Space Arc Engineering also distributes. For procurement teams comparing brands, credible high-range PCE superplasticisers from other suppliers include Sika ViscoCrete, the MBS (Master Builders Solutions) MasterGlenium range, BASF-lineage admixtures, STP, and within the Indian repair/waterproofing market Dr. Fixit; each has its own slump-retention and strength profile. The honest position is that admixture performance is mix-specific: the best product is the one validated by trial mixes against your cement, SCMs and aggregates, and against the current Fosroc TDS. Space Arc Engineering’s value as an authorised Fosroc distributor and applicator is in matching Auramix 388 to the right mix design, confirming dosage, and supplying it as part of a complete, compatible Fosroc concrete system rather than a single product in isolation.
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