_{Our team was tasked to carry out the waterproofing of a newly constructed reinforced concrete underground water tank designed to store potable water for a large commercial complex. The waterproofing solution needed to meet stringent health and safety standards, provide resistance to high water pressure, and ensure long-term performance. To address these requirements, we used a combination of Cementitious Waterproofing, Crystalline Injection, and a GRP (Glass Reinforced Plastic) Lining System to fully seal the structure and enhance its durability.}

Site Condition and Project Considerations

• The tank structure had active leakage points at construction joints and pipe penetrations

• The surface exhibited micro-cracks and honeycombing in some areas

• The client required a non-toxic, corrosion-resistant, and long-lasting waterproofing system compatible with drinking water storage

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Solution Implementation

‍1. Crystalline Injection – Active Leakage Control

• Low-pressure injection of hydrophilic crystalline resin was used to seal active leakage points in construction joints and cold joints.

• The material penetrated deeply and formed insoluble crystals within the capillaries of the concrete, creating an internal waterproof barrier.

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2. Cementitious Waterproofing – Surface Sealing Layer

• A flexible cementitious waterproofing slurry was applied in two coats across the internal surfaces.

• This addressed surface porosity, provided corrosion protection to the reinforcement, and ensured a strong bonding surface for the GRP lining.

• All internal corners were provided with cement-sand fillets for structural transition protection.

3. GRP Lining System – Final Protective Layer

• A Glass Reinforced Plastic (GRP) lining was applied to the internal surfaces of the tank.

• The GRP system was built using multiple layers of fiberglass mat impregnated with isophthalic-grade polyester resin, ensuring chemical resistance and impermeability.

• Special detailing was performed around nozzles, manholes, and internal features to ensure a seamless finish.

• The surface was top-coated with a food-grade, UV-stable resin suitable for potable water.

4. Inspection and Testing

• A spark test was conducted on the GRP lining to confirm there were no pinholes or discontinuities.

• The tank was then filled and subjected to a 72-hour hydrostatic test. No leakage or seepage was observed.

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Summary and Outcome‍

Systems Applied: Hydraulic Crystalline Injection Grout; Flexible Cementitious Waterproofing Coating, and GRP (Glass Reinforced Plastic) Lining System (with food-grade topcoat).

The waterproofing system achieved full water retention with no seepage during testing. The integrated solution of internal sealing, cementitious coating, and GRP lining ensured robust protection for long-term use in a high-immersion environment.