About Fosroc Proofex WG

Fosroc Proofex WG is a purpose-built epoxy waterproof grout used to close the most failure-prone gaps in a below-ground waterproofing scheme: the points where pile caps, box-outs and penetrations interrupt a continuous membrane. It is supplied as a three-component system comprising an epoxy base resin, a liquid hardener and a pack of specially graded inert fillers. When the three are combined, the result is a dense, void-free, non-shrink grout that can be placed in sections from 20 mm up to 100 mm thick in a single operation.

In Indian construction practice, the waterproofing membrane over a basement raft or podium is rarely the part that leaks. Water finds its way in at junctions, around projecting pile heads, and at the rebated box-outs left for columns and services. Proofex WG exists to make those junctions as reliable as the flat field of the membrane. Because it is designed to be compatible with the Fosroc Proofex range of pre-applied and bonded membranes (such as Proofex Engage and Proofex 3000), the grout bonds into the same continuous, mechanically anchored waterproofing and ground-gas barrier rather than sitting as a separate, weaker patch.

The non-shrink characteristic is central to how it performs. Conventional cementitious mortars shrink as they cure, opening hairline gaps at the very interface they are meant to seal. Proofex WG holds its volume, so it maintains intimate surface contact and a structural bond to both the concrete and the membrane. Combined with its high strength and chemical resistance, this makes it suitable for aggressive below-grade environments including sites built on gas-contaminated or reclaimed land, where both hydrostatic water and ground gases such as methane and radon must be excluded. For Space Arc Engineering clients across Delhi NCR and Pan-India, it is the specialist detailing product that protects the integrity of an entire tanking system at a fraction of the cost of a remedial injection campaign later.

The technical insight

The defining property of Proofex WG is that it is a filled epoxy system rather than a cementitious one. The graded inert fillers do two jobs: they raise the placed density to around 2025 kg/m3 (giving a dense, low-permeability matrix) and they moderate the exotherm so the grout can be poured in thick sections of up to 100 mm without cracking from heat build-up. Strength development is rapid and substantial: compressive strength reaches roughly 36 N/mm2 at just 6 hours (24 degrees C), about 89 N/mm2 at 1 day, 93 N/mm2 at 3 days and approximately 100 N/mm2 at 7 days, with 7-day tensile strength near 14 N/mm2 and flexural strength near 32 N/mm2. That early strength lets follow-on trades proceed quickly. The trade-off engineers must respect is pot life, which is short and highly temperature-sensitive: roughly 60 minutes at 10 degrees C, 30 minutes at 20 degrees C and only 15 minutes at 30 degrees C. On a typical Indian summer site that 15-minute window governs batch size and crew choreography. Mix only what can be placed in the available time, and where possible work in cooler parts of the day or pre-condition materials.

Where it is used

• Sealing and waterproofing pile-cap heads where piles project into the basement raft
• Filling and sealing column and service box-outs within a Proofex membrane envelope
• Detailing junctions and transitions in below-grade tanking to maintain membrane continuity
• Forming watertight and gas-tight seals on sites built over gas-contaminated or reclaimed land
• Localised grouting at penetrations through structural slabs and capping beams
• Integrating with Proofex Engage / Proofex pre-applied membrane systems at complex geometry

Key advantages

• Non-shrink, so it keeps full surface contact and a structural bond at the very junction that usually leaks
• Fully waterproof and chemically compatible with the Fosroc Proofex membrane range, forming one continuous barrier
• High compressive, tensile and flexural strength suitable for load-bearing pile-cap zones
• Rapid strength gain (usable compressive strength in hours) accelerates the construction programme
• Placeable in thick sections of 20-100 mm in a single pour, reducing layering and cold joints
• Resistant to oils, greases, fats, most chemicals, mild acids and alkalis, and to fresh and sea water
• Suitable for ground-gas protection schemes on contaminated or made-up ground

Limitations & considerations

• Short, temperature-sensitive pot life (about 15 minutes at 30 degrees C) demands disciplined small-batch mixing and fast placement
• Three-component system must be mixed in full, correct proportions on site; part-mixing risks under-cure and weak grout
• Designed for detailing (pile caps, box-outs) at 20-100 mm, not as a general large-area waterproofing membrane on its own
• Higher material cost than cementitious grouts, justified only where the watertight/gas-tight detail is critical
• Epoxy resin and hardener require care in handling, ventilation and PPE; substrate must be clean, sound and suitably prepared
• Performance depends on correct integration with the surrounding Proofex membrane, so it should be detailed and installed by trained applicators

Selection & best practice

Specifications

Industry use cases

How we position Fosroc Proofex WG

Proofex WG is a specialist detailing product, not a standalone tanking system, and it is at its best as the junction-sealing component of a full Fosroc Proofex membrane scheme (Proofex Engage or Proofex 3000 for the field membrane, with Supercast swellable waterstops and PVC waterstops where construction-joint movement is involved, and Nitoproof / Brushbond ranges for above-grade and tankable surfaces). Within Fosroc’s own line it sits alongside epoxy grouts such as the Conbextra EP range, but Proofex WG is distinguished by being formulated specifically for waterproof pile-cap and box-out detailing rather than general structural grouting. Against the wider Indian market, the comparable role is filled by epoxy or polymer waterproof grouts and pile-cap detailing systems from Sika (Sikadur grouts with Sikaproof/SikaBit membranes), MBS (MYK Schomburg / Aquafin systems), Dr. Fixit (Pidilite, with its Roofseal and Newcoat membrane ecosystem) and STP (Supreme, with the Insulay/Membrex range). The honest reason to specify Proofex WG over a generic epoxy grout is system compatibility: when the surrounding membrane is a Proofex product, using the matching Proofex WG grout gives a single, warrantable, chemically compatible barrier rather than a mix of vendors at the one detail most likely to leak. Where the membrane is from another manufacturer, the like-for-like detailing grout from that same system is usually the more coherent choice.

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