Frequently Asked Questions

For a 50,000-litre underground water storage tank in Ghaziabad constructed in reinforced concrete, what is the complete waterproofing system using MC-Bauchemie products, and how should MC-Dicht 1 be integrated with the structural concrete and construction joint waterproofing?

The waterproofing of a large underground potable water storage tank in Ghaziabad requires a multi-layer approach that addresses the three distinct failure modes of concrete water tanks: permeation through the concrete body (capillary water flow through the concrete pore structure under the hydrostatic head of the stored water), leakage through construction joints (the most common failure mode in large tanks that are cast in sections — the joint between the slab and the walls, and between successive wall pours), and leakage through cracks (primarily shrinkage cracks that develop in the concrete walls as the concrete cools and shrinks after curing, and long-term thermal movement cracks in tanks exposed to sun). A complete MC-Bauchemie waterproofing system for a 50,000-litre underground tank addresses each failure mode. Stage 1 — Integral concrete waterproofing. The most effective and durable approach for a new tank is to incorporate MC-Admix C8000 crystalline waterproofing admixture into the concrete mix for the raft slab and all walls. At the standard dose of 0.8 to 1.0 percent by mass of cement, MC-Admix C8000 reduces the permeability of the concrete to below the EN 934-2 and IS 9103 requirements for waterproof concrete, provides self-sealing capability for hairline cracks up to 0.4 mm (which will inevitably form in a large tank slab and walls from plastic and drying shrinkage), and is potable water safe. Specify the concrete mix as C35/45 with water-cement ratio not exceeding 0.45, including MC-Admix C8000. Stage 2 — Construction joint waterproofing. All construction joints in the tank (slab-to-wall horizontal joint, wall lift joints, and pipe penetration entries) must be waterproofed individually using a combination of water-stop (Polyvinyl Chloride water-stop strip cast into the concrete at the joint face — 200 mm wide minimum, formed into a J-profile) and MC-Bauchemie MC-Injekt injection tube (a plastic tube containing a water-swelling agent, pre-installed at the joint face before the second concrete pour, which can be re-injected with MC-Bauchemie MC-Injekt 2600 hydrophilic PU foam if leakage develops at the joint after construction). For pipe penetrations through the tank wall, use mechanical pipe entry collars (Link-Seal or equivalent) supplemented by MC-Stop hydraulic cement grouting. Stage 3 — Surface waterproofing render — MC-Dicht 1. After the tank concrete has cured for a minimum of 28 days (important — do not apply MC-Dicht 1 on green concrete as the concrete must achieve full strength and the majority of drying shrinkage before the render is applied, otherwise the render will crack with the concrete), apply MC-Dicht 1 to the internal face (positive side — the face that will contact the stored water) of all walls and the floor as a two-coat system totalling minimum 10 mm thickness on the floor and 8 mm on the walls. Preparation: the internal concrete surface must be roughened by mechanical means (wire brushing, scabbling, or high-pressure water jetting at 2,000 psi) to remove laitance and expose an open, absorptive surface for mechanical key. Pre-wet to SSD condition. Apply the first coat of MC-Dicht 1 by trowel at 5 to 6 mm thickness, pressing firmly into the surface. Allow the first coat to reach leather-hard stage (typically 6 to 12 hours at 25 to 30 degrees C), dampen the surface of the first coat, and apply the second coat at 4 to 5 mm, working perpendicular to the first coat direction to eliminate pinholes. Apply the waterproofing render to all surfaces continuously — do not leave gaps at the wall-floor junction. The junction between wall and floor is the most critical area and must be detailed with a 45-degree cove fillet of MC-Dicht 1 at minimum 50 mm radius before the main render coats. Stage 4 — Curing. Maintain damp curing of the MC-Dicht 1 render for 7 days by wet hessian covering or regular water misting three to four times per day. Do not allow the render to dry rapidly in the Indian climate — in Delhi NCR summer, the tank interior can heat significantly and must be shaded from direct sunlight during curing. Stage 5 — Water tightness testing. After 28 days from render completion, fill the tank to capacity and observe for 72 hours — any visible seepage or wet patches indicate a defective area requiring remediation. Contact Space Arc Engineering for system design, construction joint detailing, and complete product supply for underground tank waterproofing projects across Ghaziabad and Delhi NCR.