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A building owner in Ghaziabad has a 3-storey below-grade basement car park in an 18-storey residential tower that was built 12 years ago — the basement is now showing water ingress at multiple points on the perimeter retaining walls, particularly at the construction joint between the raft foundation and the retaining walls — the external membrane is inaccessible (backfilled with compacted fill and pavements) — what is the complete internal waterproofing remediation strategy using MC-Protect 2K, and how should the active leak points at the construction joints be treated before applying the coating?

A 12-year-old basement car park with water ingress at retaining wall construction joints is one of the most common and most technically demanding basement waterproofing remediation problems in Delhi NCR residential construction, because: the external membrane (if one was installed) has typically partially failed after 10 to 15 years, the construction joints were inadequately waterproofed in the original construction (a pervasive defect in Indian basement construction practice), and the entire external face is inaccessible under compacted backfill and hard landscaping. The complete internal remediation strategy is as follows. Phase 1 — Condition survey and diagnosis (before any work): map all visible water ingress points on the internal face of all retaining walls — categorise as: (a) active running leaks (water flowing freely through crack or joint); (b) weeping damp (moisture seeping slowly through the concrete); (c) efflorescence staining (dried mineral deposits indicating past water ingress path now dry). Focus immediate treatment on active running leaks which must be stopped before applying the area waterproofing coat. Identify the construction joint locations (typically at the base of the retaining wall, visible as a horizontal line 50 to 150 mm above the raft slab level) — the raft-to-wall construction joint is the highest risk location because: (i) it is the interface between two separately placed concrete pours where the waterstop (if any) was the only waterproofing; (ii) it is subject to differential settlement between the raft and wall causing crack development; (iii) it is at the level of peak groundwater pressure in high water table conditions. Phase 2 — Active leak point stopping treatment: for active running leaks and seeping joints, MC-Protect 2K area coating cannot be applied directly over running water because the water flow will flush out the fresh slurry. Stop active leaks first using MC-Injekt 2K hydrophilic polyurethane injection resin (for cracks) or a rapid-setting hydraulic repair mortar (Vandex Plug or equivalent) for joint gaps: (i) locate the exact leak path by tracing the water back from the visible emergence point; (ii) drill 12 mm diameter injection holes at 150 to 200 mm spacing along the construction joint, angled at 30 to 45 degrees to intersect the joint plane 50 to 75 mm behind the wall face; (iii) inject MC-Injekt 2K two-component hydrophilic PU under low pressure (2 to 3 bar) — the PU reacts with the flowing water and expands to fill the crack or joint gap, stopping the water flow within 30 to 60 seconds of injection; (iv) for small point leaks that cannot be reached by injection, use a hydraulic quick-set mortar (mixed to a stiff crumb, pressed firmly into the leak point and held for 2 to 3 minutes while the mortar sets against the water pressure); allow all injection repairs to cure minimum 24 to 48 hours before proceeding with MC-Protect 2K coating. Phase 3 — Surface preparation for MC-Protect 2K: after all active leaks have been stopped: (i) remove all lime and mineral deposits (efflorescence) by wire brushing or light mechanical grinding — these deposits are incompatible with cementitious coating adhesion; (ii) chip out any loose, hollow-sounding concrete at the construction joint zone with a cold chisel (minimum 10 mm deep, width of the joint) and fill flush with non-shrink cementitious repair mortar (MC-Grout 300 or equivalent) — seal the joint thoroughly as the highest-risk waterproofing point; (iii) fill all visible surface voids and defects with cementitious repair mortar; (iv) clean the entire wall surface by pressure washing to remove dust, laitance, and contamination; (v) pre-wet the surface to saturated-surface-dry condition immediately before applying MC-Protect 2K. Phase 4 — MC-Protect 2K application — 3-coat specification for hydrostatic pressure resistance: mix MC-Protect 2K per the product data sheet ratio (powder to liquid polymer) — typically 4.5 to 5 kg powder per 1 kg liquid polymer (or per the current batch instruction). Coat 1 (bond coat): apply MC-Protect 2K at 1.0 to 1.2 kg per square metre by stiff masonry brush using a scrubbing motion to force the slurry into the concrete pores; at the construction joint location, apply an additional full build coat over the joint as a first pass and embed 100 mm wide fibreglass mesh tape into the wet coat to reinforce this highest-risk zone; allow coat 1 to cure to firm (4 to 6 hours at 25 degrees Celsius). Coat 2: apply at 1.2 to 1.5 kg per square metre over the full wall face (coat 2 over the fibreglass mesh at joints) — ensure coverage is complete with no pinholes; allow 4 to 6 hours. Coat 3 (finish coat): apply at 1.0 to 1.2 kg per square metre over the full face; smooth finish with a damp brush for appearance. Post-application curing: mist spray with clean water 3 to 4 times per day for 3 days — do not apply screed or plaster for minimum 7 days. Verification: after 28 days, inspect for any new active seepage points — if any, localise and inject with MC-Injekt 2K before applying a touch-up coat of MC-Protect 2K at that location. Long-term performance note: the MC-Protect 2K internal coating will stop active water ingress and reduce the basement relative humidity significantly. However, for a 3-level deep basement under sustained external groundwater pressure in Delhi NCR alluvial conditions, a drainage channel system (running along the base of the walls, collecting seepage water and pumping to a sump) combined with MC-Protect 2K coating is the most resilient long-term solution — the drainage channel relieves hydrostatic pressure before it builds to the point of penetrating the coating. Space Arc Engineering supplies MC-Protect 2K, MC-Injekt 2K, MC-Grout 300, and complete basement waterproofing remediation packages for residential and commercial tower basements in Ghaziabad, Delhi NCR, Noida, and Uttar Pradesh.

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