Master Builders Solutions MasterRoc MP 307 CE
A low-viscosity acrylic gel injected into hairline cracks to shut off pressurised water for good — even where cement grout can’t reach.
What is it?
MasterRoc MP 307 CE is a two-component, low-viscosity acrylic injection resin that reacts with an accelerator and hardener inside a crack or fissure to form a soft, rubber-like, water-blocking gel.
Where is it used?
Metro and road tunnel linings, shafts, dam galleries, diaphragm walls, basements and lift pits fighting groundwater through fine cracks or joints.
Why use it?
At roughly 5 cP it’s thinner than most epoxies and PU grouts, so it reaches hairline fissures they can’t, then cures flexible (>300% elongation) so it keeps sealing after minor crack movement instead of re-cracking.
How is it applied?
Pumped through packers or a pre-cast hose using a calibrated two-component pump with a static in-line mixer at 1:1 by volume; gel time is tuned on site between roughly 3 and 22 minutes via the hardener dose.
About Master Builders Solutions MasterRoc MP 307 CE
MasterRoc MP 307 CE belongs to Master Builders Solutions’ MasterRoc range, the company’s underground-construction chemistry line that also covers rock-bolting resins and sprayed-concrete accelerators. It is a highly reactive acrylic resin system — a resin, an accelerator, a reactive Part B, and a powder hardener that governs gel time — mixed on site through a two-component pump. Once injected it gels into an opaque, rubber-like solid within minutes and keeps curing over the following days, forming a water-blocking gel that tolerates the minor movement every underground structure sees. It is CE-marked to EN 1504-5, the European standard for concrete crack-injection products.
This matters most on Indian projects where cementitious grout is too coarse and epoxy too rigid: metro and highway tunnel joints, deep basements below the monsoon water table, dam galleries, and lift-pit leaks found after handover. Space Arc supplies and applies MasterRoc MP 307 CE across Delhi NCR and pan-India, alongside MasterRoc’s PU injection resins for higher-flow active leaks and MasterSeal membranes for surface waterproofing, so specifiers can match chemistry to the flow rate and crack width in front of them.
The technical insight
The EN 1504-5 declaration reads U (S2) W(1)(1/2/3)(5/40) — a resin for filling non-structural cracks with a stated swelling capacity and water-tightness class. Two things drive site performance. Viscosity: the neat resin runs about 5 cP and the activated mix around 7 cP at 20°C, well under the 60 cP ceiling EN 1504-5 allows, so it migrates into fissures a thicker PU or epoxy gel would bridge over. Reactivity: hardener dosage (0.2-5%) shifts gel time from roughly 22 minutes down to under 4 at 20°C, and slows further in cold soil — which is why a trial shot on site matters more than the datasheet number.
Where it is used
- Crack and fissure injection as a swelling, flexible fill (EN 1504-5, category S)
- Permanent sealing of tunnel linings, shafts and masonry against static groundwater pressure above 12 bar
- Stopping minor active water inflow through construction and cold joints, and honeycombed concrete
- Activating pre-installed injection (water-stop) hoses at raft, basement and diaphragm-wall joints
- Curtain injection ahead of a tunnel face or shaft excavation to pre-seal the ground
- Soil stabilisation around excavations where fine fissures need consolidating, not just sealing
- Leak arrest in lift pits and retaining walls below the water table on completed structures
Key advantages
- Very low viscosity (5 cP resin, ~7 cP mixed) reaches hairline cracks PU and cementitious grouts bridge over
- Gel time adjustable on site from about 3 to 22 minutes via hardener dosage, to match distance and temperature
- Cures into a flexible, rubber-like gel (>300% elongation) that keeps sealing after minor movement
- CE-certified to EN 1504-5 with a documented watertightness rating, not just a marketing claim
- Non-corrosive and reported harmless in contact with groundwater
- Workable across 5°C to 40°C, covering most Indian site conditions
- Uncured resin and equipment clean up with plain water, cutting solvent handling on site
Limitations & considerations
- Needs a calibrated two-component pump and static mixer — not a hand-mixed product for untrained crews
- Activated pot life is roughly 5 hours at 20°C and shortens sharply with more hardener
- It’s a flexible sealing gel, not a structural grout — tear strength is modest (>0.08 MPa), unsuited to load-bearing repair
- Four separate components with different dosing ratios add site logistics and room for dosing error
- Gel time is temperature-sensitive, so a site trial before the main run is essential
Selection & best practice
Run a small trial injection at actual site temperature before the full sequence — printed gel times are lab figures at 20°C and shift in cold soil. Calibrate the pump and static mixer for a true 1:1 ratio each shift, and pick the hardener percentage from the dosage table to suit injection distance rather than a fixed default. Keep components sealed and dry, use activated material within its roughly 5-hour pot life, and flush the pump with water immediately after each session.
Specifications
| Chemistry | Two-component, low-viscosity acrylic (acrylate) injection resin |
| Standard / certification | CE-marked to EN 1504-5; class U(S2)W(1)(1/2/3)(5/40) |
| Viscosity | Resin ~5 cP; mixed material ~7 cP @ 20°C |
| Mixing ratio | Resin : Part B = 1:1 by volume, plus 5% accelerator and 0.2-5% hardener |
| Gel time | Approx. 3 to 22 minutes @ 20°C, adjustable via hardener dosage |
| Elongation at break | >300% |
| Watertightness | Seals against static groundwater pressure above 12 bar (1.2 MPa) |
| Application temperature | 5°C to 40°C |
| Pack sizes | Resin 20 kg can; Accelerator 1 kg can; Part B 20 kg can; Hardener 0.3 kg can |
Industry use cases
Metro & road tunnels
Sealing segmental lining joints against groundwater ingress on underground metro and highway sections.
Deep basements & diaphragm walls
Injecting construction joints and tie-rod holes below the monsoon water table across NCR.
Dams & hydropower
Curtain and fissure injection in inspection galleries to control seepage in dam and barrage structures.
Lift pits & retaining structures
Arresting leaks found after handover in lift pits and below-grade parking structures.
Raft foundations
Activating pre-cast injection hoses at raft and pile-cap joints as a re-injectable backup to the primary waterstop.
Frequently asked questions
How is it different from a PU injection grout?
Can it be injected while water is actively flowing?
What equipment do we need?
How long before the leak actually stops?
Is it safe near reinforcement steel or drinking-water structures?
What’s the shelf life and storage?
How we position Master Builders Solutions MasterRoc MP 307 CE
Within the MasterRoc range, MP 307 CE sits alongside the MP 355 polyurethane injection resins: reach for the PU on a fast, flowing leak needing an immediate foam plug, and use MP 307 CE for the finer, permanent gel seal afterward or on hairline cracks PU won’t enter. For surface waterproofing rather than injection, it pairs with MasterSeal membranes. Fosroc’s crack-injection range leans on structural epoxy systems built for bonding and strengthening, not a flexible, swelling water seal, so there isn’t a genuine like-for-like Fosroc substitute at this acrylic-gel, curtain-grouting tier.
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Authorised distribution, technical advice & professional application across Delhi NCR and Pan-India.