Fosroc Structuro 343
New-generation polycarboxylic-ether superplasticiser engineered for tunnel lining segments, self-compacting concrete and high-early-strength structural pours.
What is it?
Fosroc Structuro 343 (officially designated Structuro 343T) is a new-generation, water-based superplasticising admixture built on polycarboxylic-ether (PCE) polymer chemistry. It is a high-range water reducer that lets concrete producers cut mixing water sharply while keeping the mix highly fluid.
Where is it used?
Used in precast tunnel-lining segments and cast-in-situ tunnel linings, self-compacting and self-levelling concrete (SCC), and high-performance structural concrete where high early and ultimate strength is required — across metro, hydropower, infrastructure and precast yards in India.
Why use it?
It delivers strong water reduction without loss of workability, lifting early and ultimate compressive strength, producing stable homogeneous concrete and enabling extremely fluid pours that place without vibration. It is chloride-free and complies with EN 934-2.
How is it applied?
Dosed into the concrete at the batching plant or truck at 0.6 to 1.5% by weight of cementitious material (typically around 1% for SCC), added with the gauging water — never onto dry cement — and mixed thoroughly to disperse the polymer.
About Fosroc Structuro 343
Fosroc Structuro 343 — carried in the official Fosroc range as Structuro 343T — sits in the Structuro family of high-performance concrete admixtures and is one of Fosroc’s tunnel-and-SCC focused superplasticisers. It is a new-generation additive engineered around polycarboxylic-ether (PCE) comb-polymer technology, the dispersant chemistry that has replaced older naphthalene and melamine sulphonates in demanding concrete worldwide. The product is water-based, non-flammable and chloride-free, which makes it suitable for reinforced and prestressed concrete where embedded steel must be protected against corrosion.
The defining behaviour of Structuro 343 is high water reduction with retained workability. PCE molecules adsorb onto cement grains and hold them apart through steric (physical) repulsion rather than the weaker electrostatic action of legacy plasticisers. The practical result is that a producer can remove a large fraction of the mixing water — lowering the water-cement ratio and densifying the hardened matrix — while the fresh concrete stays extremely fluid and self-levelling. That combination is exactly what tunnel-lining and self-compacting concrete demand: a dense, durable, low-permeability matrix that still flows into congested reinforcement and intricate segment moulds without segregation and, in many cases, without mechanical vibration.
In the Indian construction landscape, Structuro 343 is most relevant to large infrastructure: metro tunnel segment casting yards, hydropower and irrigation tunnels, underground utilities and precast operations where dimensional precision and surface finish matter. It is positioned for mixes that need a normal workability window plus high initial strength — for example, segment moulds that must be stripped and re-cycled quickly, or pours where early formwork release improves productivity. Because it raises early strength, it supports faster mould turnover and tighter casting cycles, a direct commercial benefit in high-volume precast yards.
Space Arc Engineering supplies Structuro 343 / 343T as an authorised Fosroc distributor across Delhi NCR and Pan-India, alongside the wider Structuro and Auramix admixture ranges. For any specific project, the controlling document is the current Fosroc Technical Data Sheet for the grade and region — trial mixes with site materials should always confirm dosage, slump retention and strength before bulk supply, because cement chemistry, supplementary cementitious materials, aggregates and ambient temperature all shift admixture response.
The technical insight
The performance of Structuro 343 comes from its polycarboxylic-ether backbone. Unlike sulphonated naphthalene formaldehyde (SNF) plasticisers that disperse cement mainly by electrostatic charge, PCE polymers carry long polyethylene-oxide side chains that create steric hindrance — a physical “spacer” effect that keeps cement particles separated far more effectively and at lower dosage. This is why a PCE such as Structuro 343 achieves high water reduction (the basis of its high-range classification) while still producing a flowing, cohesive, non-bleeding mix. The lower water-cement ratio translates directly into a denser microstructure, higher compressive strength at both early and 28-day ages, and reduced permeability, which is the real durability driver in aggressive tunnel and underground environments. Critically for structural work, the admixture is chloride-free (water-soluble chloride content is held to a low limit under EN 934-2), so it does not introduce chloride ions that would accelerate reinforcement corrosion. Compliance with EN 934-2:2010 Tables 3.1 and 3.2 as a high-range water reducer / superplasticiser is the formal benchmark; the practical control parameters on site remain dosage, the water-cement ratio it allows you to reach, and slump-flow retention over the placing window.
Where it is used
- Precast tunnel-lining segment casting (metro, road and rail tunnels)
- Cast-in-situ tunnel and shaft linings in hydropower and irrigation works
- Self-compacting concrete (SCC) for congested or inaccessible reinforcement
- Self-levelling concrete requiring flow without mechanical vibration
- High-performance structural concrete needing high early and ultimate strength
- Precast and prestressed elements where fast mould turnover improves productivity
- Low water-cement-ratio durable concrete for underground and aggressive exposure
Key advantages
- High water-reducing power that lowers the water-cement ratio and densifies the hardened matrix
- Retains high fluidity and workability despite strong water reduction
- Significantly improves both early and ultimate compressive strength
- Produces stable, homogeneous, cohesive concrete resistant to segregation and bleeding
- Enables extremely fluid, self-placing concrete that can be poured without vibration
- Chloride-free formulation — safe for reinforced and prestressed concrete
- Water-based and non-flammable, simplifying on-site storage and handling
- Complies with EN 934-2:2010 (Tables 3.1 and 3.2) as a high-range superplasticiser
- Supports faster mould stripping and tighter casting cycles in precast yards
Limitations & considerations
- Not a waterproofing, curing or repair product — it is purely a concrete admixture and must be used within a designed mix
- Performance is mix-specific: cement type, SCMs (fly ash / GGBS), aggregates and temperature all affect dosage and slump retention, so trial mixes are essential
- Overdosing PCE superplasticisers can cause excessive retardation, bleeding or segregation — dosage must be controlled
- Must be added with the gauging water; adding directly onto dry cement gives poor dispersion
- PCE admixtures can show sensitivity / incompatibility with certain cements or clay-bearing aggregates, which must be checked in trials
- Region- and grade-specific properties must be confirmed against the current Fosroc Technical Data Sheet (the ‘343T’ designation and exact figures vary by market)
- Not a stand-alone set retarder, accelerator or air-entrainer; combine with complementary admixtures only after compatibility trials
Selection & best practice
Always start from the current Fosroc Technical Data Sheet for the Structuro 343 / 343T grade supplied in your region and run laboratory and site trial mixes with your actual cement, supplementary cementitious materials, aggregates and water before bulk use. Add Structuro 343 with the gauging water — never onto dry cement — and ensure thorough, consistent mixing so the PCE polymer disperses fully. Begin dosing near the lower end of the 0.6 to 1.5% by weight of cement range and adjust upward to hit the target slump-flow, watching for any sign of bleeding, segregation or excessive retardation that signals overdosing. Verify water-cement ratio, slump-flow retention over your actual placing window, and early-age strength against the casting cycle you need. For SCC, validate filling ability, passing ability and segregation resistance with the standard fresh-SCC tests. Store the product sealed in original containers in dry, shaded conditions between 2°C and 40°C and use within its stated 12-month shelf life. For project-specific mix design support, dosage optimisation and supply across Delhi NCR and Pan-India, consult Space Arc Engineering as your authorised Fosroc distributor.
Specifications
| Product type | High-range water-reducing superplasticiser admixture |
| Chemical base | Polycarboxylic-ether (PCE) polymer, water-based |
| Official Fosroc designation | Structuro 343T |
| Chloride content | Chloride-free; water-soluble chloride (Cl⁻) ≤ 0.10% |
| Dosage range | 0.6 to 1.5% by weight of cement (typical ~1% for SCC) |
| Standards compliance | EN 934-2:2010, Tables 3.1 and 3.2 (superplasticiser / high-range water reducer) |
| Flammability | Non-flammable (water-based) |
| Shelf life | 12 months in sealed original containers |
| Storage temperature | 2°C to 40°C, dry and shaded |
Industry use cases
Metro & rail tunnels
Casting precast tunnel-lining segments to tight tolerances and fast mould-turnover cycles, where high early strength enables quicker stripping and re-use of moulds.
Hydropower & irrigation
Cast-in-situ tunnel and shaft linings requiring dense, low-permeability, durable concrete able to flow into formwork under demanding underground conditions.
Precast & prestressed yards
High-performance SCC and structural elements where extreme fluidity, no-vibration placement and strong early strength raise productivity and finish quality.
Commercial & infrastructure RCC
Low water-cement-ratio, high-strength structural concrete for congested reinforcement zones, columns and transfer elements needing self-compaction.
Frequently asked questions
Is Fosroc Structuro 343 the same as Structuro 343T?
What is the recommended dosage of Structuro 343?
Does Structuro 343 contain chlorides — is it safe for reinforced concrete?
What standard does Structuro 343 comply with?
How is Structuro 343 different from a standard plasticiser like Conplast?
Can Structuro 343 be used to make self-compacting concrete (SCC)?
Where can I buy Fosroc Structuro 343 in India?
How we position Fosroc Structuro 343
Structuro 343 (343T) is Fosroc’s tunnel-and-SCC-oriented polycarboxylic-ether superplasticiser, sitting alongside other Structuro grades such as Structuro 311 (self-compacting / self-levelling), Structuro 335 and Structuro 351 (general manufactured concrete), and the Auramix range — choose the grade by application, workability window and strength target. Within Fosroc, for ordinary workability rather than high-range performance, the lignosulphonate/naphthalene-based Conplast plasticisers are a more economical step down. Against competitors, Structuro 343 competes with Sika’s PCE superplasticisers (SikaPlast / Sika ViscoCrete), BASF/MBS Master Builders Solutions MasterGlenium, and other PCE admixtures in the Indian market; for tunnel and SCC work the practical selection criteria are water-reduction efficiency, slump-flow retention with your cement, and verified EN 934-2 / IS 9103 compliance. Note that Dr. Fixit (Pidilite) and STP are primarily waterproofing and protective-coating brands and do not compete directly in high-range superplasticiser admixtures, though they appear alongside Fosroc on the same infrastructure projects. Space Arc Engineering can supply Structuro 343 and cross-recommend the right Fosroc grade for each pour.
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