Table of Contents
- Why Pure Polyurea for Large Potable Water Reservoirs?
- Engineering Case Study: Potable Water Reservoir Lining Specification
- Technical Profile of Polyurea Rayston P
- Concrete Substrate Preparation per EN-1504-2
- Layer Specification: Primer to Seamless Membrane
- Comparative Analysis: Cold-Applied Polyurethane (Impermax Aqua 2K)
- Polyurea Rayston P Technical Data Summary
- Engineering Value of System Certifications
- Critical Site & Specification Pitfalls to Avoid
- Specification Summary & Technical Recommendation
Why Pure Polyurea for Large Potable Water Reservoirs?
Lining large-scale potable water containment structures demands a high-performance elastomeric barrier capable of bridging substrate cracks, withstanding continuous hydrostatic pressure, and complying strictly with public health standards. The engineering objective is not a cosmetic coating, but a seamless, monolithic containment liner: a compatible primer to consolidate the concrete substrate, followed by a hot-sprayed pure polyurea membrane. Because enclosed concrete reservoirs lack ultraviolet (UV) exposure, an aliphatic topcoat is intentionally excluded from the interior wet envelope.
This technical guide details the design criteria and site verification parameters for Polyurea Rayston P. For complete technical documentation and system approvals, consult the Polyurea Rayston P product page, our technical Knowledge Hub, or the dedicated Drinking Water Reservoirs engineering section.
Engineering Case Study: Potable Water Reservoir Lining Specification
This reference model represents a high-capacity, enclosed reinforced concrete drinking water reservoir, outlining how multi-layer chemical barriers resolve corner details, floor-to-wall junctions, and penetration details using Polyurea Rayston P. For related civil containment schemes, see Liquid Containment and Fire Water Tanks.
Design & Application Parameters:
- Structure: Enclosed reinforced concrete water storage reservoir for municipal distribution.
- Scope: Floor slab, vertical walls, expansion joints, plinths, and service pipe penetrations.
- System Build-up: Concrete primer applied at 0.2–0.4 mm dry film thickness (DFT) → hot-sprayed pure polyurea membrane at 1.8–2 kg/m² (yielding approximately 1.9–2 mm thickness) → no internal aliphatic topcoat.
- Hygiene Requirement: Uncompromising adherence to WRAS BS6920 potable water contact certification without introducing unverified chemical coatings to the wet surface.
Technical Profile of Polyurea Rayston P
Polyurea Rayston P is an aromatic pure polyurea system engineered with a controlled, moderate cure profile relative to ultra-rapid polyureas. This controlled gel window allows superior leveling and uniform surface wet-out over intricate concrete geometry before curing.
Primary Civil & Industrial Applications
In addition to potable water storage, Rayston P is routinely specified for primary and secondary containment, wastewater treatment plants, desalinization facilities, irrigation canals, and retaining basins requiring high mechanical durability and chemical resistance.
Governing Consumption & Membrane Thickness
| Parameter | Target Specification |
|---|---|
| Application Consumption | 1.8–2 kg/m² |
| Nominal Film Thickness | 1.9–2 mm |
Site inspection teams must utilize consumption weight tracking alongside ultrasonic dry-film thickness measurements to ensure regulatory compliance.
Accreditation & Quality Standards
| Standard / Certification | Reference & Scope |
|---|---|
| Concrete Surface Protection | CE EN-1504-2 |
| European Technical Assessment | ETA 16/0148 (EAD 030350-00-0402) |
| British Board of Agrément | BBA 18/5582 with a declared working life of 25 years |
| Potable Water Suitability | WRAS approval per BS6920 |
To verify testing parameters or incorporate these standards into tender documentation, consult the Certified Systems and Technical Documents Hub.
Concrete Substrate Preparation per EN-1504-2
A continuous high-pressure elastomeric lining performs only as well as the mechanical bond established with the substrate. In accordance with EN-1504-2 guidelines, the concrete surface must undergo mandatory mechanical preparation:
- Surface Decontamination: Abrasive blast-cleaning or diamond grinding to remove all laitance, curing compounds, efflorescence, oil, and loose debris, achieving an open-pore concrete profile.
- Cohesion & Strength: The substrate must demonstrate a minimum pull-off tensile strength of 1.5 N/mm² and adequate compressive strength.
- Defect Remediation: Bug holes, honeycombing, static cracks, and dynamic construction joints must be primed and filled with compatible thixotropic epoxy or polyurethane mortars before membrane application.
- Moisture Verification: Concrete moisture must remain below 4% for standard epoxy primers (e.g., Rayston Epoxy 100). Substrates exhibiting higher residual moisture (up to 8%) mandate an osmotic moisture-tolerant epoxy primer (such as Humidity Primer) to eliminate the risk of osmotic blistering.
Layer Specification: Primer to Seamless Membrane
1. Concrete Primer Layer
- Target Thickness: 0.2–0.4 mm DFT.
- Engineering Role: Penetrates the porous concrete matrix, seals micro-cavities to prevent air outgassing during hot spray, and creates a chemical-mechanical anchor for the polyurea.
- Material Selection: Selected based on site conditions: 100% solids epoxy (Rayston Epoxy 100) for standard dry concrete, water-based epoxy for damp slabs, or fast-curing Polyurea Primer.
2. Primary Waterproofing Membrane: Polyurea Rayston P
- Chemical Base: 100% solids, two-component pure aromatic polyurea.
- Application Method: Plural-component high-pressure impingement spray equipment (temperatures ~65–75°C, pressure ≥140 bar).
- Application Rate: 1.8–2 kg/m² yielding 1.9–2 mm continuous membrane.
- Characteristics: Crack-bridging capability, zero volatile organic compounds (VOCs), and near-instant return to service.
3. Interior Enclosed Tanks: Why Aliphatic Topcoats Are Excluded
While an aliphatic polyurethane topcoat (0.1–0.3 mm) is standard practice for external roofs to preserve color stability against UV radiation, it is strictly omitted from enclosed water reservoirs:
- Absence of Solar Radiation: Zero UV degradation occurs inside a dark, enclosed tank. While aromatic polyureas darken upon exposure to sunlight, this cosmetic shift has zero effect on mechanical properties or chemical resistance.
- Direct Potable Compliance: Rayston P is independently certified by WRAS (BS6920) for direct, unsealed immersion contact with potable water.
- Interface Integrity: Eliminating unnecessary secondary coatings removes an adhesive interface, ensuring the pure polyurea operates as the single, monolithic containment liner.
Comparative Analysis: Cold-Applied Polyurethane (Impermax Aqua 2K)
Where project scale, physical access, or budget makes mobilizing high-pressure heated reactor equipment impractical, Krypton Chemical provides a certified cold-applied alternative: Impermax Aqua 2K. This solvent-free, two-component polyurethane is applied manually via squeegee or roller:
| Performance Criterion | Polyurea Rayston P (Hot Spray) | Impermax Aqua 2K (Cold Manual) |
|---|---|---|
| Polymer Chemistry | Pure aromatic polyurea | Solvent-free flexible polyurethane |
| Application Method | Heated plural-component machine (≥140 bar) | Manual application (notched squeegee / roller) |
| Minimum Consumption | 1.8–2 kg/m² (≈ 1.9–2 mm) | ≥ 2 kg/m² (≈ 1.5 mm) |
| Potable Certification | WRAS (BS6920) | European Directive 98/83/EC |
| Harmonized Standard | CE EN-1504-2 | CE EN-1504-2 |
| Optimal Project Scope | Strategic civil reservoirs & large infrastructures | Small-to-medium tanks, repair zones & tight spaces |
Polyurea Rayston P Technical Data Summary
| Technical Property | Specified Value / Standard |
|---|---|
| Chemical Nature | Two-component, solvent-free pure polyurea |
| Application Rate | 1.8–2 kg/m² |
| Nominal Membrane Thickness | 1.9–2 mm |
| International Approvals | WRAS BS6920 · CE EN-1504-2 · ETA 16/0148 · BBA 18/5582 (25 yr) |
| Substrate Primer DFT | 0.2–0.4 mm (adapted to surface porosity) |
| Topcoat Requirement | None required for interior closed tanks (0.1–0.3 mm for external UV exposure only) |
Engineering Value of System Certifications
- Public Health Safety: Compliance with WRAS BS6920 confirms that the cured liner does not leach toxic heavy metals, promote microbiological growth, or impart taste or odor to drinking water.
- Structural Concrete Protection: CE EN-1504-2 certification guarantees crack-bridging resilience, protection against carbonation, and complete water impermeability under hydrostatic head pressure.
- Proven Durability: BBA certification (18/5582) provides an independent assessment certifying a 25-year service life expectancy under demanding environmental conditions.
- Monolithic Security: High-pressure hot spray application eliminates laps, overlaps, seams, and mechanical fasteners, neutralizing the primary failure mode of sheet membrane liners.
Critical Site & Specification Pitfalls to Avoid
- Unverified Engineering Specifications: Specifying arbitrary tensile strengths, elongation, or gel times in tender documents without direct cross-reference to official manufacturer technical data sheets.
- Imposing Superfluous Internal Topcoats: Mandating an aliphatic polyurethane topcoat inside dark, closed tanks increases project cost and creates an unnecessary adhesive boundary without delivering any functional or hygienic benefit.
- Visual Guesswork on Consumption: Relying solely on visual thickness inspection rather than strict material weight tracking (≥1.8–2 kg/m²) risks localized under-thickness and premature lining compromise.
- Overlooking Moisture Dynamics: Applying standard epoxy primers on concrete with >4% moisture content without testing can cause vapor-induced blistering and localized delamination.
- Chemical Cross-Contamination: Conflating hot-spray pure polyurea (Rayston P) with cold-applied polyurethane (Aqua 2K) in contract specifications, or transferring certification numbers across distinct chemical systems.
Specification Summary & Technical Recommendation
Engineering a durable potable water containment lining requires a strictly enforced sequence: thorough concrete surface preparation conforming to EN-1504-2, substrate priming at 0.2–0.4 mm, and a hot-sprayed, seamless membrane of Polyurea Rayston P applied at 1.8–2 kg/m² (yielding approximately 1.9–2 mm). For smaller civil works, Impermax Aqua 2K serves as an independently verified, cold-applied alternative.
For project-specific specification clauses, bid documentation reviews, or on-site technical consulting, consult the engineering advisory team at Krypton Chemical Solutions.
About the Manufacturer: Krypton Chemical, S.L. is an established European manufacturer founded in 1999, specializing in liquid-applied waterproofing membranes, protective coatings, and industrial resin flooring under the Rayston and Krypton ProLine brands. Operating from its modern production hub in Tarragona, Spain, the company delivers engineering specification support and material distribution to major infrastructure projects across more than 70 countries worldwide.