Dr. Fixit PU Plain Injection
A hydro-insensitive, two-component polyurethane resin that penetrates hairline cracks and cures into a tough, flexible, water-resistant seal — even while the crack is still wet.
What is it?
A reactive two-component polyurethane injection resin that penetrates fine cracks, then reacts with substrate moisture to cure into a tough, flexible rubber.
Where is it used?
Injected through drilled packer holes into cracks and joints in RCC and masonry — basements, water tanks, reservoirs, dams, tunnels, sewers and manholes.
Why use it?
It’s hydro-insensitive: no dry substrate needed, it cures in the dampness it’s meant to stop, and carries CFTRI approval for potable water contact.
How is it applied?
Base and hardener are mixed 2:1 by volume and injected through mechanical NRV packers at a minimum 0.2 N/mm² (2 bar), continued until resin emerges from the adjacent packer, then cured undisturbed for 24 hours.
About Dr. Fixit PU Plain Injection
Dr. Fixit PU Plain Injection is Pidilite’s low-viscosity, non-foaming polyurethane resin for pressure-injection crack sealing and water-stop grouting, part of the Building Repairs range alongside PU Foam Injection and Epoxy Injection Grout. It reaches the far end of a hairline crack and cures whether that crack is dry or actively weeping, reacting into a rubber that’s flexible rather than glass-hard, so the seal tolerates the small movement a real crack keeps making.
On Indian sites this is a repair-stage product, specified once a leak has shown up — a raft-slab crack, a water-tank construction joint, seepage in a lift pit — rather than at design stage. Space Arc supplies and applies it across Delhi NCR for that use case, where injection happens under real hydrostatic pressure through mechanical packers, not brushed on.
The technical insight
The standout number is viscosity: under 400 cP mixed (ASTM D2196), low enough to travel through hairline cracks a thicker epoxy grout can’t enter. It’s non-foaming — the resin fills the crack itself and cures to a dense rubber (Shore A ≥50), unlike Dr. Fixit’s own PU Foam Injection, which expands to block a fast leak first. Bond strength above 2.5 N/mm² shows it’s doing structural bonding, not just plugging a gap; the 0.2 N/mm² minimum injection pressure and 24-hour cure aren’t arbitrary — under-pressure work leaves voids that resurface as leaks months later.
Where it is used
- Injection grouting of drinking water reservoirs and water tanks
- Pressure sealing of hairline and structural cracks by packer injection
- Stopping high-volume water ingress in basements and underground structures
- Water-stop grouting of construction joints in dams and hydel power channels
- Sealing sewers, manholes and utility boxes against groundwater ingress
- Horizontal damp-proofing against capillary rising moisture in masonry
Key advantages
- Very low viscosity (<400 cP) for deep penetration into hairline cracks
- Hydro-insensitive — cures in water, so wet cracks don’t need drying first
- CFTRI-approved non-toxic formulation, suitable for potable water tanks
- Strong bond to brick, stone and cementitious substrates, wet or dry
- Cures to a flexible rubber, so the seal tolerates ongoing minor movement
- Predictable 24-hour cure lets packers be cut and holes made good next day
Limitations & considerations
- Must never be diluted with water or solvent — it disrupts the reaction
- Below 15°C, needs conditioning above 30°C for at least 3 hours before use
- Sold only in a 5 kg kit — no smaller pack for a single-crack job
- Non-foaming, so wrong for a fast gushing leak — Foam Injection suits that better
Selection & best practice
Space packers to the crack’s depth and width, and inject bottom-up so rising resin pushes air and water ahead of it. Mix only what will be used within pot life — the sheet doesn’t fix a figure, so batch small and confirm working time on site. Hold the 0.2 N/mm² minimum pressure and keep injecting until resin emerges from the next packer. Leave the system undisturbed for the full 24-hour cure, and in winter condition the resin above 30°C for 3 hours rather than injecting it cold.
Specifications
| Chemistry / System | Two-component (2K), highly reactive polyurethane resin |
| Mixing Ratio (Base : Hardener) | 2 : 1 by volume |
| Density of Mixed Resin | < 1.25 g/cc (ASTM D1475) |
| Viscosity of Mixed Resin | < 400 cP (ASTM D2196) |
| Bond Strength | > 2.5 N/mm² (ASTM C882) |
| Tensile Strength / Elongation at Break | > 1 MPa / > 80% (ASTM D412) |
| Shore A / Shore 00 Hardness | ≥ 50 / ≥ 80 (ASTM D2240) |
| Minimum Injection Pressure | 0.2 N/mm² (2 bar) |
| Pack Size / Shelf Life | 5 kg kit; 24 months from manufacture, unopened, cool & dry |
Industry use cases
Underground Water Tanks & Reservoirs
Injection sealing of joints and shrinkage cracks in RCC or masonry reservoirs, where CFTRI potable-water approval is often the deciding factor.
Basements & Below-Grade Structures
Stopping active seepage through raft-slab and retaining-wall cracks in basements and lift pits, where the crack is already wet.
Infrastructure — Dams, Tunnels & Metro
Water-stop grouting of joints and tunnel-lining junctions on larger civil projects via an engineer-specified packer grid.
Municipal & Industrial Utilities
Sealing manholes, sewers and utility boxes against groundwater ingress and exfiltration.
Frequently asked questions
What’s the difference between PU Plain Injection and PU Foam Injection?
Can it be injected into a crack that’s already leaking water?
Is it safe to use inside a drinking-water tank?
What equipment does the applicator need on site?
How soon can the structure go back into service?
Does cold weather in North India affect application?
How we position Dr. Fixit PU Plain Injection
Within Dr. Fixit’s Building Repairs range, PU Plain Injection sits between PU Foam Injection (first response for a gushing leak) and Epoxy Injection Grout (structural, load-bearing repair). For bearing grouting under machine bases, specifiers usually move to Pidigrout 10M or epoxy-based Pidigrout EG-3-S instead. Cross-brand, the nearest comparison is Fosroc’s Conbextra EP epoxy injection range — similar intent, but built on rigid epoxy rather than PU’s flexible, water-reactive chemistry, so the real choice is whether the crack needs to keep moving (PU) or carry structural load (epoxy).
Related Waterproofing products
Source Dr. Fixit PU Plain Injection for your project
Authorised distribution, technical advice & professional application across Delhi NCR and Pan-India.