About Fosroc Polyurea WPK

Fosroc Polyurea WPK is a two-component, 100% solids pure polyurea spray elastomer engineered for high-performance waterproofing and surface protection of concrete and steel. The system is supplied as two matched parts, Fosroc Polyurea AMINE WPK (the resin / amine component) and Fosroc Polyurea ISO WPK (the isocyanate hardener), which are sprayed simultaneously through heated, high-pressure plural-component equipment. On contact the two streams react in seconds, building a seamless, self-levelling elastomeric film that has no joints, no overlaps and no laps to fail.

What sets WPK apart from conventional liquid-applied membranes is speed. The material gels in about 5 to 10 seconds and becomes tack-free in roughly 35 to 45 seconds, so very large areas can be coated in a single shift and the surface can be returned to service quickly, even on vertical and overhead faces where a liquid coating would sag. Because it is 100% solids with zero VOC, there is no solvent flash-off, no shrinkage from solvent loss, and the full dry-film thickness is achieved in one or two passes.

For Indian projects, this combination is valuable wherever downtime is expensive or site conditions are harsh, for example STPs and ETPs, metro and railway structures, refinery and port assets, bridge decks and large podium slabs. Space Arc Engineering supplies Fosroc Polyurea WPK as an authorised Fosroc distributor across Delhi NCR and Pan-India, together with the matched Fosroc Primer 195 and applicator guidance. Because spray polyurea is wholly dependent on correctly calibrated, heated equipment and a properly prepared substrate, it is an applicator-trained system rather than a brush-or-roller product, and Fosroc requires that only approved sprayers apply it.

The technical insight

Fosroc Polyurea WPK is an aromatic pure polyurea, formed by the near-instant reaction of an amine-terminated resin (AMINE WPK) with an isocyanate (ISO WPK). The reaction is moisture-insensitive and so fast that it is largely independent of ambient humidity, which is why polyurea cures reliably where moisture-cured polyurethanes can blister or foam. Both components are pre-heated to roughly 70-80 C and atomised at high pressure so they impinge-mix and react on the substrate within seconds, giving the characteristic 5-10 second gel. The cured film reaches an elongation of more than 360% (ASTM D412) with a tensile strength of 19 N/mm2, meaning it can stretch dramatically to accommodate movement and crack-bridging while remaining tough, and a Shore A/D hardness of 94/50 keeps it abrasion and puncture resistant (235 mg loss per 1000 cycles, Taber H18, ASTM D4060). One practical limitation to understand is that, being aromatic, WPK can discolour under prolonged UV exposure; this is purely cosmetic and does not affect physical performance, but where colour stability matters a polyurea or polyurethane UV-stable topcoat is recommended.

Where it is used

• Below-grade and podium waterproofing of concrete slabs and retaining structures
• Internal lining of water-retaining, collection and sewage-treatment tanks
• Bridge and bridge-deck waterproofing under asphalt or wearing courses
• Internal and external coating of pipes and pipelines
• Roof waterproofing on large or trafficked roof areas
• Coating and lining of marine structures and marine equipment
• Internal and external lining of rolling stock and rail vehicles
• Theme-park, sculpture, water-park and aquarium waterproof coatings
• Protective lining for airport, smelter and refinery / petrochemical installations
• Landscape water features and external water tanks

Key advantages

• Seamless, joint-free monolithic membrane with no laps or overlaps to fail
• Extremely fast cure (gel 5-10 sec, tack-free 35-45 sec) enabling rapid return to service
• 100% solids and zero VOC, no solvent flash-off or shrinkage
• High elongation (over 360%) for excellent crack-bridging and movement accommodation
• Excellent impact, abrasion and puncture resistance versus epoxy systems
• Can be sprayed on vertical and overhead surfaces without sagging
• Very low water-vapour permeability and good chemical resistance to many acids, alkalis, fuels and seawater
• Wide service temperature range of -30 C to +135 C
• Fundamentally prevents corrosion when lining steel, improving asset durability

Limitations & considerations

• Requires specialised heated, high-pressure plural-component spray equipment (Graco / Gusmer / Glas-Craft) and Fosroc-approved trained applicators, not a brush or roller product
• Aromatic chemistry can discolour under prolonged UV; a UV-stable topcoat is needed where appearance matters (physical properties unaffected)
• Demands rigorous surface preparation: blast-cleaning of steel to Sa 2.5 and priming with Fosroc Primer 195 before application
• Very short gel time leaves no working time and is unforgiving of equipment or ratio errors, so calibration is critical
• Substrate temperature should generally be above the dew point (about 3 C) and cure can be slowed below 15 C
• Not a self-applied or small-patch product, so it is uneconomic for very small or piecemeal areas
• Conditional or not recommended against a few aggressive chemicals such as concentrated hydrochloric acid and certain solvents

Selection & best practice

Specifications

Industry use cases

How we position Fosroc Polyurea WPK

Fosroc Polyurea WPK sits at the high-performance, fast-track end of Space Arc’s waterproofing portfolio, chosen when speed, seamlessness and toughness justify specialist spray application. Within the Fosroc range it complements the hand-applied hybrid polyurea Fosroc Polyurea WH 100 / WH 200 (for smaller areas or where spray rigs are impractical) and the spray pure-polyurea Fosroc Polyurea WPE, and it is paired with Fosroc Primer 195. For projects where spray polyurea is not viable, cementitious and acrylic alternatives such as Fosroc Brushbond or Nitoproof are more appropriate. Against the wider market, comparable spray pure-polyurea and high-performance membranes include Sika (Sikalastic / Sikalastic-841 ST polyurea), BASF / Master Builders Solutions (MasterSeal polyurea and PUR/PUA systems), Dr. Fixit (Pidilite) liquid-applied PU membranes, and STP Limited polyurea and PU coatings. WPK’s honest advantage is its near-instant cure, very high elongation and zero-VOC chemistry; its honest trade-offs are the need for trained applicators with heated high-pressure equipment, rigorous surface preparation, and a UV topcoat where appearance matters. Space Arc Engineering supplies WPK as an authorised Fosroc distributor across Delhi NCR and Pan-India with applicator and specification support.

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