Fosroc Conplast WP200
A chloride-free permeability-reducing admixture that lowers the water:cement ratio and waterproofs concrete from within the mass, not just at the surface.
What is it?
Conplast WP200 is a Fosroc integral waterproofing admixture: a chloride-free, brown liquid based on a formulated blend of dispersants that disperses instantly in the mix water. It reduces concrete permeability throughout the section rather than forming a surface film.
Where is it used?
Water-retaining and water-excluding concrete: basements, raft and pile-cap foundations, retaining walls, water tanks and sumps, swimming pools, roof slabs, sewage and treatment works, and any reinforced concrete exposed to ground or standing water.
Why use it?
It lets you achieve workability at a lower water:cement ratio, so the hardened concrete is denser, less permeable and higher in compressive strength. Because protection is integral to the mass, it survives surface damage that would defeat an applied coating.
How is it applied?
Dosed into the concrete at the batching plant or mixer at the recommended rate per 100 kg of cement, added with the mix water or to the wet concrete and mixed to a uniform consistency. It is not a coating and needs no separate application trade.
About Fosroc Conplast WP200
Fosroc Conplast WP200 is an integral, liquid waterproofing admixture used to make structural concrete substantially less permeable to water. Unlike brush- or spray-applied membranes that protect only the face of an element, Conplast WP200 is mixed into the concrete itself, so the resistance to water penetration is built into the full thickness of the section. This “waterproofing from within” approach is one of the most cost-effective ways to deliver durable, watertight reinforced concrete in Indian conditions, where high water tables, monsoon loading and aggressive soils put basements, foundations and water-retaining structures under constant hydrostatic pressure.
Chemically, Conplast WP200 is a chloride-free product based on a formulated blend of dispersants and is supplied as a brown solution that disperses instantly in water. The dispersing action improves the efficiency with which the available water wets the cement and aggregate, so the concrete reaches its target workability at a noticeably lower water:cement ratio. Lowering free water is the single most important lever for durability: it cuts capillary porosity, reduces bleed channels and tightens the pore structure that water would otherwise travel through. The result is concrete that is denser, stronger and far slower to absorb water, while still placing and compacting easily on site.
For specifiers and contractors across Delhi NCR and Pan-India, the practical appeal is reliability. A coating can be punctured by follow-on trades, by backfilling, or by drying shrinkage cracks; a properly designed Conplast WP200 mix keeps its low-permeability character even where the surface is later chipped, drilled or abraded. Space Arc Engineering supplies Conplast WP200 as an authorised Fosroc distributor and supports project teams with mix-design dosage guidance, sampling and logistics so the admixture is matched correctly to the cement and aggregates actually being used on the job.
The technical insight
The mechanism of Conplast WP200 is fundamentally different from the hydrophobic and crystalline routes in Fosroc’s own range, and getting that distinction right is what separates a watertight pour from a leaking one. Conplast WP200 does not block pores with a reactive crystal (as Conplast Crystalline does) and does not line them with a water-repellent stearate film (as the hydrophobic Conplast WP does). Instead its dispersants deflocculate the cement grains, releasing trapped mixing water and allowing a genuine reduction in the water:cement ratio at constant slump. Because permeability in hardened concrete scales steeply with w/c ratio, even a modest reduction collapses the interconnected capillary network through which water migrates. In practice this means the admixture only delivers its full benefit when the batching team actually exploits the workability gain to trim water, rather than keeping the same water and simply enjoying a wetter mix. The product is chloride-free, so it does not introduce a corrosion risk to embedded reinforcement, and it carries no bitumen, avoiding the staining and bond problems associated with bituminous waterproofers. It is compatible with other Fosroc admixtures, so on demanding pours it is commonly run alongside a Conplast superplasticiser, which lets you push the w/c ratio down further while preserving placeability. Conplast WP200 should be regarded as one component of a watertight-concrete system: it must sit on top of a sound, well-graded, adequately cement-rich mix design, correct cover, controlled crack widths and good compaction. The admixture sharply reduces permeability of the concrete matrix, but it cannot bridge a structural crack or a poorly detailed construction joint, which is why it is normally paired with proper joint treatment such as a Fosroc Hydrotite or Supercast waterbar.
Where it is used
- Basement raft slabs, retaining walls and lift-pit construction below the water table
- Foundations, pile caps and ground beams in damp or aggressive soils
- Water-retaining structures: overhead and underground water tanks, reservoirs and sumps
- Sewage and effluent treatment works, channels and clarifier tanks
- Swimming pools and decorative water features
- Roof slabs, terraces and parapet concrete subject to ponding and monsoon exposure
- Marine and coastal reinforced concrete exposed to splash and high humidity
- Precast and in-situ elements where dense, low-permeability concrete is specified for durability
Key advantages
- Reduces concrete permeability throughout the full mass, not just at the surface
- Integral protection is retained even if the concrete surface is later damaged, drilled or abraded
- Allows the same workability at a lower water:cement ratio, improving density and durability
- Improves compressive strength at equal workability through the reduced water content
- Chloride-free, so it poses no chloride-induced corrosion risk to reinforcement
- Contains no bitumen, avoiding staining and bond issues with later finishes
- Disperses instantly in water and is simple to dose at the batching plant or mixer
- Compatible with other Fosroc admixtures, including superplasticisers, for high-performance watertight mixes
Limitations & considerations
- It is a permeability reducer, not a crack bridge: it cannot seal structural cracks or moving joints, which need a waterbar or joint sealant
- Benefit is only realised if the workability gain is used to lower the water content; keeping water constant negates the waterproofing effect
- It does not replace good mix design, adequate cement content, proper cover, compaction and curing
- Higher-than-recommended dosage can increase retardation and over-extend workability
- Performance depends on site QA; results should be confirmed by trial mixes with the project’s actual cement and aggregates
- As an in-mix admixture it cannot remediate an existing leaking structure, which requires a repair or coating system instead
Selection & best practice
Establish the dosage by trial mix using the project’s own cement, aggregates and target slump, working within the recommended 0.40 to 0.75 litres per 100 kg of cement, and confirm the result with a water-absorption or permeability check rather than slump alone. Crucially, instruct the batching plant to take the improved workability as a reduction in mixing water, so the water:cement ratio actually falls. Add Conplast WP200 with the mixing water or to the wet concrete and mix to a uniform consistency; never add it to dry cement. Treat it as part of a complete watertight-concrete strategy: combine it with a properly designed dense mix, correct reinforcement cover, controlled crack widths, well-detailed construction and movement joints fitted with a Fosroc waterbar, and disciplined curing. On demanding low-permeability pours, run it alongside a compatible Fosroc superplasticiser to push the w/c ratio lower without losing placeability. Avoid over-dosing, protect drums from extreme temperatures, and use a calibrated dispenser for batch-to-batch consistency.
Specifications
| Product type | Integral permeability-reducing (waterproofing) admixture for concrete |
| Chemical basis | Formulated blend of dispersants (chloride-free) |
| Appearance | Brown solution; disperses instantly in water |
| Chloride content | Nil (to BS 5075) |
| Bitumen content | None; does not incorporate bitumen |
| Recommended dosage | 0.40 to 0.75 litres per 100 kg of cement (confirm by trial mix) |
| Standards reference | BS 5075 / BS EN 934 (admixtures for concrete) |
| Action | Reduces water:cement ratio at equal workability; lowers permeability through the concrete mass |
| Compatibility | Compatible with other Fosroc admixtures, including superplasticisers |
| Specific gravity | Refer to current Fosroc TDS (typical of liquid admixtures); verify on supplied batch |
Industry use cases
Commercial & residential basements
Below-water-table basement rafts and retaining walls in Delhi NCR high-rises use Conplast WP200 to deliver dense, low-permeability structural concrete that stays watertight even where the surface is later penetrated by services.
Water & wastewater infrastructure
Municipal water tanks, reservoirs, sumps and sewage treatment tanks specify the admixture for durable, low-absorption concrete that resists continuous hydrostatic and effluent exposure.
Foundations in aggressive ground
Pile caps, raft foundations and ground beams cast in damp or chemically aggressive soils benefit from the reduced water:cement ratio and tighter pore structure for long-term durability.
Roofs, terraces & podiums
In-situ roof slabs, terraces and podium decks subject to monsoon ponding are cast with Conplast WP200 to cut water uptake and support the overlying waterproofing system.
Swimming pools & water features
Pool shells and decorative water bodies use the admixture for watertight, dense concrete that complements the applied tanking and finishing layers.
Frequently asked questions
Is Conplast WP200 the same as Conplast WP?
Will Conplast WP200 on its own make my basement fully waterproof?
What is the correct dosage and where is it added?
Does it cause corrosion of reinforcement?
Can it be used together with a superplasticiser?
Can Space Arc supply Conplast WP200 across India?
How we position Fosroc Conplast WP200
Within Fosroc’s own waterproofing range, Conplast WP200 is the dispersant-based, water-reducing route to lower permeability. It sits alongside the hydrophobic Conplast WP and Conplast WL (pore-lining stearate chemistry) and Conplast Crystalline (reactive crystal growth), each of which reduces permeability by a different mechanism; on critical structures it is paired with Fosroc joint products such as Supercast waterbars or Hydrotite hydrophilic seals to handle joints and cracks that no admixture can address. Compared with competitor integral waterproofers, it competes directly with Sika WT-200/Sika Watertight Concrete admixtures, Dr. Fixit Pidiproof LW+ and similar integral liquids, MBS (MYK/BASF Master Builders) MasterLife and MasterPel ranges, and STP/ Krystaline crystalline systems. Honestly positioned, Conplast WP200 is a strong, well-proven choice where the goal is denser, lower-permeability structural concrete through water reduction; where the priority is self-sealing of fine cracks, a crystalline product such as Conplast Crystalline or a competitor crystalline system may be more appropriate. Space Arc Engineering, as an authorised Fosroc distributor in Delhi NCR with Pan-India reach, supplies the genuine product and advises on which Fosroc solution fits the structure, exposure and specification.
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