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Home› Solutions› Grouting & Injection› Tunneling
🚇 Grouting & Injection

Tunneling
Waterproofing
& Grouting

Specialist hydro-active polyurethane injection resins for tunnelling operations — water cutting and water control, waterproofing of concrete structures, and consolidation of unstable zones in the drill face area. User-friendly, environmentally conscious systems for underground infrastructure projects in Sri Lanka.

Hydro-Active PU Resins Water Cut-Off Ground Consolidation Single-Component
Tunneling Waterproofing Sri Lanka
Service Overview

Hydro-Active Polyurethane
Injection for Tunnelling

Introducing user-friendly and environmentally conscious polyurethane injection resins for tunnelling operations. Our single-component polyurethane injection resins are available in three distinct ranges tailored for the specific challenges of underground construction and tunnel waterproofing.

Tunnelling and underground construction present some of the most demanding waterproofing challenges in civil engineering. Water ingress into tunnels, culverts, underpasses and underground structures is not merely a durability issue — it is a safety risk that can destabilise ground, corrode reinforcement, damage electrical and mechanical systems, and create hazardous working and operating conditions.

With straightforward one-component injection equipment and no mixing requirements on site, our Hydro-Active PU systems are faster and more reliable to apply than two-component systems — reducing operator error, improving quality consistency, and enabling injection works to continue in wet, confined and challenging underground environments.

Three Specialist Ranges

Single-Component PU Resins —
Three Distinct Application Ranges

Our single-component polyurethane injection resins are available in three distinct ranges, each engineered for a specific tunnelling application:

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Range 01
Water Cutting & Water Control

Rapid-reacting hydrophilic PU resins specifically formulated to stop or control active water flows within tunnel structures. On contact with water, the resin undergoes an immediate chemical reaction — expanding aggressively to fill cracks, joints and voids and form a watertight seal against flowing water pressure.

✓ Stops active water inflows instantly
✓ Works under high hydrostatic pressure
✓ Flexible cured foam — movement tolerant
✓ Fast reaction — seconds in high-flow conditions
✓ Construction joints and segment joints
✓ Applicable in flowing water conditions
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Range 02
Waterproofing of Concrete Structures

Medium-reactivity hydro-active PU resins for systematic waterproofing of tunnel lining segments, cast-in-situ tunnel walls, culverts and underground concrete structures. Injected through the concrete lining to fill and seal cracks, construction joints and interface zones between the lining and surrounding ground.

✓ Tunnel lining crack and joint injection
✓ Lining-to-ground interface sealing
✓ Culverts, underpasses & box culverts
✓ Controlled expansion for void filling
✓ Compatible with segment & bored tunnels
✓ Long-term waterproof performance
🪨
Range 03
Consolidation & Stabilization of Unstable Zones

Specially formulated expanding PU resins for consolidation and stabilisation of loose, fractured or water-saturated ground in the drill face area ahead of tunnelling operations. Injected ahead of the excavation face to stabilise weak ground, reduce water inflows and provide temporary support during tunnelling advance.

✓ Drill face stabilisation ahead of TBM
✓ Weak ground and fractured rock treatment
✓ Water-saturated ground control
✓ Permeation grouting of granular soils
✓ Temporary ground support during advance
✓ Works with standard one-component pumps
Single Component PU Injection Equipment
System Advantage

Why Single-Component
Systems Excel in Tunnelling

Traditional two-component injection systems require precise on-site mixing of two resins — creating risks of incorrect mixing ratios, equipment blockages, wasted material and inconsistent performance. In the challenging environment of underground construction — confined spaces, poor lighting, vibration, wet conditions and time pressure — these risks are amplified.

Our Hydro-Active single-component PU resins eliminate these risks entirely. Pre-formulated and ready to use, they are pumped directly from the container through simple one-component injection equipment — no mixing, no metering, no wasted material. Water in the crack or substrate activates the expansion reaction automatically and consistently every time.

  • No on-site mixing — pre-formulated single component, ready to use directly
  • Simple equipment — standard one-component injection pump, no complex mixing head
  • Consistent performance — no risk of incorrect mixing ratios affecting cure quality
  • Reduced waste — only pump what you need, no mixed resin to discard
  • Faster application — less equipment setup time, more time injecting
  • Environmentally conscious — lower waste, no uncured two-component mix disposal
  • Works in confined spaces — compact equipment suited to tunnel access restrictions
Applications

Tunneling Grouting
Applications We Cover

🚇
Road & Rail Tunnels
Waterproofing and crack injection for road tunnels, metro tunnels and rail underpasses — concrete lining joints and water ingress points.
🌊
Subsea & River Tunnels
High-pressure waterproofing for tunnels below water bodies — where hydrostatic head is significant and watertight integrity is critical.
🔲
Box Culverts & Underpasses
Joint sealing and waterproofing of precast and cast-in-situ box culverts, underpasses and pedestrian subways.
⚡
Utility Tunnels
Waterproofing of cable tunnels, service tunnels, drainage tunnels and utility corridors against water ingress.
🏗️
Cut-and-Cover Structures
Post-construction waterproofing and joint injection for cut-and-cover tunnels and below-ground structures.
🪨
Ground Stabilisation
Pre-injection of loose ground, fractured rock and water-bearing strata ahead of tunnel excavation to improve stability and reduce inflow.
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Water & Sewage Tunnels
Waterproofing of water supply tunnels, sewer tunnels and wastewater conveyance structures — maintaining water quality and preventing inflow/outflow.
🏘️
Basement & Underground Car Parks
Deep basement and multi-level underground car park waterproofing — the same techniques as tunnelling applied to below-grade building structures.
🌉
Bridge & Flyover Underbelly
Waterproofing of bridge soffits, pier caps and flyover deck undersides against water ingress and concrete spalling.
The Underground Challenge
Why Tunnel Waterproofing is Different
💪
High Hydrostatic Pressure

Underground water pressure can exceed several bar — requiring resins and techniques capable of injecting against and sealing under significant hydrostatic head.

🌫️
Confined Environment

Limited access, poor ventilation, restricted working space and safety constraints demand compact, simple equipment with minimal operator complexity.

⏱️
Time-Critical Operations

Tunnelling programmes are time-sensitive and expensive. Waterproofing treatments must be fast-acting, reliable and completed with minimal disruption to the tunnelling advance rate.

Application Process

How Tunnel Grouting
Injection is Done

1
Leak Survey & Injection Layout
A systematic inspection of the tunnel structure identifies all water ingress points — cracks, joints, honeycombing and leaking areas. The injection layout is planned, including port positions, sequence and resin range selection for each zone.
2
Drill Injection Ports
Injection packers are drilled into the tunnel lining at 45° through the full thickness — angled to intercept the crack or joint within the concrete section. Port spacing is typically 150–300mm along the leak path.
3
Packer Installation
Mechanical or chemical injection packers are installed and tightened to form a pressure seal. For high-pressure applications, heavy-duty packers rated to the expected injection pressure are used.
4
Single-Component PU Injection
The appropriate Hydro-Active PU resin range is connected to the injection pump and pumped under controlled pressure through each packer in sequence — starting from the lowest or most active leak point. No mixing is required. Water in the substrate activates the expansion reaction automatically.
5
Reaction, Expansion & Seal
On contact with water in the cracks, joints and voids, the PU resin reacts and expands rapidly — filling all pathways and forming a watertight seal. For ground consolidation, the resin permeates the surrounding ground matrix before expanding.
6
Inspection & Secondary Treatment
After curing, the treated area is inspected for any residual seepage. Secondary injection at additional ports is carried out if required. Packer holes are filled and the surface is finished with repair mortar or waterproof coating as appropriate.
Infrastructure Experience

Underground & Infrastructure
Project Experience

Hi-Tech Concrete Solutions brings extensive experience in structural waterproofing, crack injection and grouting for underground, below-grade and infrastructure structures across Sri Lanka — the same technical expertise and certified systems that underpin our tunnelling waterproofing capability.

  • Waterproofing of the Kohuwala Flyover deck — Road Development Authority (RDA) project
  • Structural rehabilitation and crack injection at the Colombo Municipal Council building
  • Below-ground waterproofing and grouting for basement and underground structures
  • Bridge deck waterproofing and structural concrete repair — infrastructure projects
  • PU and epoxy crack injection for underground and foundation structures
  • Certified application of Supercrete NZ systems for all structural waterproofing
View Project Gallery →
Infrastructure Grouting Project Sri Lanka
Related Grouting Services

More Grouting &
Injection Solutions

💉
PU Grouting Injection
Stop active water leaks in basements, pools and underground structures with hydrophilic PU foam.
Learn More →
🔵
Epoxy Grouting & Injection
Structural crack repair restoring full concrete load capacity for dry structural cracks.
Learn More →
🏗️
Cementitious Grouting
Non-shrink grout for base plates, PT ducts, anchor bolts and structural void filling.
Learn More →
Common Questions

Tunneling Waterproofing FAQs

Can PU injection stop water in an operational tunnel without closing it?▼
In many cases, yes — injection works can be carried out in operational tunnels during off-peak hours or with temporary partial closure of a lane or section. The single-component equipment used is compact and can be operated by two persons with minimal space requirements. Specific access and safety arrangements for operational tunnel works are planned with the tunnel operator before works commence.
What is the difference between pre-injection and post-injection grouting in tunnelling?▼
Pre-injection (also called fore-poling or pre-treatment grouting) is carried out ahead of the tunnel face — injecting grout into the ground before excavation to stabilise weak zones and reduce groundwater inflow. Post-injection is carried out after the tunnel lining is constructed — injecting resin into cracks, joints and the lining-to-ground annulus to waterproof and seal the completed structure. Both techniques use our single-component PU systems, with different resin viscosities selected for each application.
Are the PU resins safe for use in water supply tunnels?▼
Our Hydro-Active PU resins are environmentally conscious formulations. For water supply tunnels and structures in contact with drinking water, we specify products with appropriate potable water approvals and low-toxicity formulations. The specific product selected depends on the application — please discuss your project requirements with our specialist so we can confirm the appropriate product certification for your situation.
How do you grout the annulus between a tunnel lining and the surrounding ground?▼
The annular gap between the outside of a bored tunnel lining and the surrounding ground is typically grouted using the grout ports built into the tunnel segments themselves — injecting cementitious or PU grout under controlled pressure to fill the gap and prevent ground movement and water migration. For existing tunnels where the annulus was not fully filled during construction, we drill through the lining and inject from inside using our specialist grouting equipment.

Tunneling Waterproofing Project?

Speak to our specialist about hydro-active PU injection for your tunnel, underground structure or infrastructure project.

🚇 Discuss Your Project 📞 +94 777 887 307 💬 WhatsApp