Fosroc Conplast MR286
A multifunctional high-range water-reducing plasticiser that cuts mix water by 15-20%, holds workability in hot weather, and improves pumpability for ready-mixed and high-fines concrete.
What is it?
Conplast MR286 is a Fosroc high-range, multifunctional plasticising and water-reducing concrete admixture built on a blend of synthetic and natural polymers that disperse cement particles to release trapped water.
Where is it used?
Ready-mixed concrete plants, pumped concrete, and mixes carrying a high proportion of fines or sand, across foundations, slabs, columns, and general structural pours in hot Indian climates.
Why use it?
It reduces mix water by 15-20% to raise strength and durability, or holds water constant to gain flowing, easily pumped concrete, while resisting the rapid slump loss common in high-temperature placing.
How is it applied?
Dispensed into the gauging water or added to the mix at the batching plant at a typical dosage of around 0.3-1.0 litres per 100 kg of cementitious material, established by site trial.
About Fosroc Conplast MR286
Conplast MR286 sits in Fosroc’s well-established Conplast MR (multi-range) family of water-reducing plasticisers, but it is positioned at the higher-performance end of that group. Where a general-purpose plasticiser like Conplast MR285 covers everyday workability gains, MR286 is formulated as a multifunctional, high-range product based on a combination of synthetic and natural polymers. These polymers adsorb onto cement grains and break down the flocs that normally trap mixing water, so the same cement content delivers more usable paste and better particle dispersion.
For contractors, consultants and ready-mix producers in India, the practical value of MR286 is its dual personality. Held at a fixed water-cement ratio, it converts a stiff, hard-to-place mix into a flowing, pumpable concrete, which is exactly what high-rise and congested-reinforcement pours need. Run the other way, with workability fixed, the admixture lets the batcher pull 15-20% of the water out of the mix. That water saving translates directly into higher compressive strength, a denser and less permeable matrix, and improved long-term durability against the chloride and sulphate exposure typical of Indian coastal and industrial sites.
A defining feature of MR286 is its behaviour in heat. Many plasticisers either flash-set or lose slump quickly when ambient temperatures climb. MR286 is engineered to maintain its plasticising effect in hot climates without introducing significant set retardation, which makes it a sensible default for summer concreting in Delhi NCR, Rajasthan, Gujarat and similar zones. It is also well suited to mixes with a high fines or sand content, where workability is otherwise difficult to achieve without over-watering. The product complies with EN 934-2, the European standard for concrete admixtures, giving specifiers a recognised performance benchmark. As an authorised Fosroc distributor and applicator, Space Arc Engineering supplies MR286 with full technical backing, site trial support and verified batch documentation.
The technical insight
The mechanism behind MR286 is electrostatic and steric dispersion. When cement contacts water it flocculates, physically trapping a portion of the mixing water inside loose clusters of grains; that trapped water is unavailable for workability. The synthetic and natural polymers in MR286 adsorb onto the cement surface, impart a like charge that pushes grains apart, and physically separate them. The freed water then lubricates the mix. This is why the same admixture can be used two ways: keep the water and you get flow, remove the water and you keep strength. Because MR286 is described as multifunctional and high-range, its water-reduction ceiling of 15-20% is meaningfully above an ordinary low-range plasticiser, approaching mid/high-range territory while remaining gentler on setting time than a naphthalene or PCE superplasticiser dosed for the same flow. The deliberate absence of strong retardation is the key engineering trade-off: the formulation prioritises early workability retention in heat over the extended open time that retarding water-reducers such as Conplast RP264 provide. For high-fines mixes the polymer blend also helps disperse the additional surface area of the fine fraction, which is the usual culprit behind sticky, high-water-demand concrete.
Where it is used
- Ready-mixed concrete production where consistent workability and water reduction are required batch to batch
- Pumped concrete for high-rise, basements and congested reinforcement, where a flowing, cohesive mix is essential
- Concrete mixes with a high proportion of fines or manufactured/crushed sand that would otherwise demand excess water
- Hot-weather concreting in Delhi NCR and other high-temperature Indian regions where slump retention is critical
- Structural elements such as foundations, rafts, columns, beams and slabs needing higher strength via reduced w/c ratio
- General reinforced concrete where improved density and lower permeability enhance durability and service life
Key advantages
- Reduces mixing water by 15-20%, increasing compressive strength and reducing permeability at the same cement content
- Multifunctional: deliver high workability and pumpability, or reduce water for higher strength, from a single admixture
- Maintains plasticising effect in hot climates without significant set retardation, ideal for Indian summer concreting
- Effective in high-fines and manufactured-sand mixes, reducing stickiness and water demand
- Improves cohesion and pumpability, lowering the risk of segregation and blockages in pump lines
- Produces denser, more durable concrete that better resists aggressive chloride and sulphate environments
- Complies with EN 934-2, giving specifiers a recognised international performance benchmark
- Liquid form integrates easily with plant dispensing systems for accurate, repeatable dosing
Limitations & considerations
- Not a high-range superplasticiser: where very high slump-flow or self-compacting concrete is required, a Conplast SP-series superplasticiser is the correct choice
- Provides minimal set retardation by design, so it is not suited to applications needing extended open/transport time, where Conplast RP264 is more appropriate
- Optimum dosage must be established by site trial with the actual cement, aggregates and conditions; overdosing can cause excessive workability or minor segregation
- Performance depends on mix design and good practice and will not compensate for poorly graded aggregates or excessive water added at site
- Being water-based it must be protected from freezing in storage and transit
- Not an integral waterproofing admixture; for that function pair with or specify a dedicated product such as Conplast WL or Conplast X421IC
Selection & best practice
Always establish the working dosage by trial mix with the project’s actual cement, fines and aggregates before site use, starting near the lower end of the 0.3-1.0 L per 100 kg cementitious range and adjusting to target. Add MR286 to the gauging water or the wet mix rather than onto dry cement, and dispense through a calibrated plant system for repeatability. Decide upfront whether the dose is being used for water reduction (hold workability, cut water for strength) or for workability (hold water, gain flow), and design the mix accordingly. Do not exceed the trial-proven dosage to chase extra slump. Maintain good curing practice; the admixture improves the concrete but does not replace proper placing, compaction and curing.
Specifications
| Product type | Multifunctional high-range plasticising / water-reducing admixture |
| Chemical basis | Blend of synthetic and natural polymers (cement dispersant) |
| Primary function | Water reduction and workability improvement |
| Water reduction | 15-20% depending on dosage |
| Typical dosage | ~0.3-1.0 litres per 100 kg of cementitious material (confirm by trial) |
| Standard compliance | EN 934-2 (concrete admixtures) |
| Form | Liquid |
| Hot-climate behaviour | Retains plasticising effect without significant set retardation |
| Recommended for | Ready-mix, pumped concrete, high-fines / high-sand mixes |
| Dispensing | Add to gauging water or wet mix; do not add to dry cement |
Industry use cases
Ready-Mixed Concrete (RMC)
RMC plants use MR286 to lock in consistent workability and slump retention across batches while reducing water for grade-target strength, particularly during summer dispatch over longer haul distances.
High-Rise & Infrastructure
Contractors rely on the flowing, cohesive mix MR286 produces for long vertical pumping runs into columns, shear walls and congested reinforcement without segregation or line blockage.
Precast & Manufactured-Sand Concrete
Producers working with crushed/manufactured sand and high fines use MR286 to disperse the fine fraction, cut water demand and improve surface finish and density.
Durability-Critical Structures
Consultants specify the 15-20% water reduction on foundations, water-retaining and coastal structures to achieve a denser, lower-permeability concrete that resists chloride and sulphate ingress.
Frequently asked questions
Is Fosroc Conplast MR286 a superplasticiser?
How much water can Conplast MR286 save in a concrete mix?
What is the recommended dosage of Conplast MR286?
Does Conplast MR286 delay the setting of concrete?
Which standard does Conplast MR286 comply with?
Can I buy Conplast MR286 in Delhi NCR and across India?
How we position Fosroc Conplast MR286
Conplast MR286 occupies the upper end of Fosroc’s Conplast plasticiser range, above the general-purpose Conplast MR285 and the cold-climate Conplast MR276, but distinct from the retarding Conplast RP264 (chosen when extended open time is needed) and from the high-range Conplast SP superplasticisers such as SP430 and SP337, which are specified when very high flow, self-compacting concrete or larger water reductions are required. Where integral waterproofing is the goal rather than water reduction, products like Conplast WL or Conplast X421IC are the correct partners. Against competitor admixtures, MR286 competes most directly with mid/high-range water-reducers such as Sika’s Sikament/Plastiment families, MBS (Master Builders Solutions, formerly BASF) MasterPolyheed/MasterPozzolith plasticisers, and STP’s products; Dr. Fixit is more commonly considered for the waterproofing-admixture role. For Indian projects prioritising hot-weather slump retention, pumpability and 15-20% water reduction without retardation, MR286 is a strong, standards-compliant choice, and Space Arc Engineering supports it with authorised supply and on-site technical guidance.
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