About Fosroc Conplast WP90E

Fosroc Conplast WP90E is an integral waterproofing admixture supplied as a fine, free-flowing powder that is added at the mixing stage so that waterproofing becomes a built-in property of the concrete or mortar rather than a surface treatment applied afterwards. It belongs to Fosroc’s long-established Conplast WP90 family of traditional pore-filling waterproofers, and the WP90E grade is positioned by Fosroc as a “concrete integral hydrophobic pore blocking waterproofing admixture.” In plain terms, the active constituents react with the products of cement hydration to part-fill and water-repel the fine capillary network that would otherwise allow water to wick through hardened concrete. The result is a denser matrix that absorbs and transmits far less water than the same mix made without it.

For an Indian site this matters because so much of our concrete distress is water-driven: monsoon-saturated basements, leaking terrace and chajja slabs, damp bathroom and balcony floors, and reinforcement corrosion in coastal and effluent-exposed structures. Conplast WP90E addresses the cause at source by lowering the concrete’s intrinsic permeability, which in turn slows the ingress of the chlorides and other aggressive ions that drive rebar corrosion. Crucially, the product is chloride-free, so unlike some older folk-remedy waterproofing additives it does not introduce its own corrosion risk into reinforced sections.

The Conplast WP90 range sold across the Indian subcontinent conforms to IS 2645:2003 (Specification for Integral Cement Waterproofing Compounds) and is certified by the Bureau of Indian Standards, which gives specifiers a recognised reference point for compliance in government, infrastructure and institutional tenders. Conplast WP90E is best understood as one part of a complete waterproofing strategy: for plain watertight concrete it can be used on its own, while for demanding below-ground or liquid-retaining work Fosroc intends it to be combined with membranes, waterstops and drained-cavity systems. Space Arc Engineering supplies Conplast WP90E as an authorised Fosroc distributor across Delhi NCR and Pan-India, with technical guidance on dosage and on selecting the right companion products for each application.

The technical insight

Conplast WP90E works on the “pore-blocking plus hydrophobic” principle rather than by crystalline growth. Hardened cement paste contains an interconnected network of gel and capillary pores; it is the larger, continuous capillaries that transmit water under pressure and by absorption. The fine inert and reactive powder fractions in the admixture physically fill and refine part of this pore network, while the hydrophobic (water-repelling) fatty-acid-type constituents line the pore walls so that the surfaces resist wetting. Together these two mechanisms cut both the volume of permeable voids and the capillary suction that draws water in, which is why Fosroc reports a markedly lower permeability versus an untreated reference sample and a reduced chloride diffusion coefficient. Because the admixture is designed to fill existing pores rather than expand, it has no particular effect on compressive strength and conforms to IS 2645:2003 for initial and final setting time, so structural performance and site programming are not compromised. The chloride-free formulation is the key durability differentiator: integral waterproofing is most needed in reinforced sections, and any admixture used there must not contribute chlorides that would depassivate the steel — WP90E satisfies this. As an integral admixture it is only as good as the concrete it is added to: low water-cement ratio, full compaction and proper curing remain essential, because the product reduces permeability but cannot heal honeycombing, cold joints or shrinkage cracks.

Where it is used

• Waterproof RCC basements, retaining walls and foundation rafts in high water-table areas
• Roof and terrace slabs, sunken slabs and floor screeds requiring water tightness
• Water-retaining and water-excluding structures such as tanks, sumps and reservoirs
• External cement plaster on facades, parapets and masonry walls exposed to driving rain
• Bathrooms, toilets, kitchens, balconies and chajjas (wet-area mortar and concrete)
• Concrete in aggressive exposure classes where reduced chloride and sulphate ingress is needed
• Repair and remedial waterproofing mortars where reduced permeability is specified

Key advantages

• Chloride-free, so safe for reinforced concrete with embedded steel
• Reduces porosity, permeability and the chloride diffusion coefficient of concrete and mortar
• No particular effect on compressive strength and conforms to IS 2645:2003 setting-time limits
• Pre-bagged powder is easy to dispense and disperses uniformly through the mix
• Improves workability of concrete and mortar mixes
• Compatible with all cements, including Pozzolana (PPC) and other blended cements
• Simple, familiar site method needing no specialist equipment or trained applicators
• BIS-certified to IS 2645:2003 for use in compliance-driven Indian tenders
• Can form part of a complete Fosroc system with membranes, waterstops and drained cavities
• Non-toxic and non-flammable, with straightforward handling precautions

Limitations & considerations

• Integral admixture only — it does not bridge or seal cracks, cold joints or honeycombed concrete
• Effectiveness depends on good mix design, low water-cement ratio, full compaction and curing
• Not a substitute for a membrane or waterstop in high-head below-ground or critical tanking situations
• Pore-blocking powders are less effective against water under significant hydrostatic pressure than crystalline or membrane systems
• Must be dispersed dry and evenly into the mix; lump formation or wrong dosage reduces performance
• Specific uniformity parameters (specific gravity, pH, chloride content) vary with mix design — refer to the product MTC for the exact configuration
• Will not waterproof an already-built or defective structure; it is a fresh-concrete/mortar solution
• Powder should be kept dry on site; exposure to moisture before use degrades it

Selection & best practice

Specifications

Industry use cases

How we position Fosroc Conplast WP90E

Conplast WP90E sits at the value, code-compliant end of Fosroc’s integral waterproofing line: a traditional, BIS-certified (IS 2645:2003) chloride-free pore-blocking powder for everyday watertight concrete and mortar. Within the Fosroc range, step up to Fosroc Supercast WCP (formerly Conplast WP402, a fatty-acid/hydrophobic blend dosed roughly one bag per cubic metre) for a more modern hydrophobic admixture, use Conplast X421IC liquid where bleeding, segregation or mass pours need a liquid integral waterproofer, and pair WP90E with Proofex membranes and Supercast waterstops for below-ground tanking. Against competitors, it is the Fosroc analogue of Sika’s integral watertight admixtures (the SikaControl WT / Sika Watertight Concrete range), MBS/MYK integral waterproofing compounds, Dr. Fixit’s Pidiproof LW+ and IWL liquids and powder waterproofing compounds, and STP’s integral waterproofers. Liquid and crystalline products (e.g. Dr. Fixit LW+, Sika WT crystalline admixtures) can offer easier dispensing or self-healing of fine cracks, whereas WP90E’s strengths are its simple pre-bagged powder form, chloride-free safety with steel, all-cement compatibility and recognised IS 2645 certification. Choose WP90E for cost-effective, standards-driven integral waterproofing of slabs, screeds, plaster and general RCC; for high-hydrostatic basements and liquid-retaining structures, treat it as one layer of a full membrane-plus-waterstop system rather than the sole defence.

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