Understanding Water-Based Hydrophilic Polyurethane Grouting for Leak Sealing

Introduction

In the field of modern waterproofing and structural repair, water-based hydrophilic polyurethane grouting has emerged as one of the most effective and sustainable methods for sealing leaks in concrete structures.

It is widely used by contractors, engineers, and waterproofing specialists to repair cracks, joints, and porous substrates exposed to continuous water pressure.

Compared to traditional materials, water-based hydrophilic polyurethane offers eco-friendly composition, superior penetration, and long-term flexibility—making it ideal for underground, tunnel, and foundation waterproofing.

This article provides a deep understanding of the working mechanism, performance features, construction process, and YURU Waterproof’s professional PU grouting solutions, designed specifically for engineering applications.

What is Water-Based Hydrophilic Polyurethane Grouting?

Water-based hydrophilic polyurethane grouting is a reactive injection material that uses moisture or water as a trigger for polymerization.
When the liquid prepolymer encounters water, it undergoes a chemical reaction that forms a flexible, expanding foam or gel capable of filling cracks and voids within the substrate.

Key Technical Features:

Main Components: Isocyanate-terminated prepolymer and hydrophilic polyether compounds.
Reaction Mechanism: Reacts with water to form polyurethane foam or gel, expanding to seal voids.
Physical Form: Liquid before injection, solid or semi-flexible foam after curing.
Environmental Safety: Water-based system, low VOC, solvent-free, and non-toxic.

Unlike solvent-based grouting, the hydrophilic variant is less aggressive, safer to handle, and performs effectively even in wet or continuously leaking environments, which makes it ideal for underground waterproofing projects.

Key Performance Characteristics and Technical Advantages

Water-based hydrophilic polyurethane grouting provides several critical technical advantages that make it a preferred choice for professional leak sealing.

a. Excellent Crack Penetration and Flowability

Its low viscosity allows deep penetration into fine cracks (<0.05mm), ensuring complete sealing of even microscopic leakage points.

b. Controlled Reaction and Expansion

The material reacts with water to form a flexible gel or foam with controlled expansion (5–20 times original volume), allowing accurate adaptation to different leak intensities.

c. Strong Adhesion and Chemical Resistance

After curing, the polyurethane gel exhibits excellent bonding with concrete, rock, and masonry, providing long-term structural stability and chemical resistance.

d. Elasticity and Flexibility

The hydrophilic structure retains moisture equilibrium, enabling re-swelling upon rehydration—a self-healing property beneficial in fluctuating wet conditions.

e. Environmentally Friendly Composition

As a water-based system, it emits minimal VOCs, meets green construction requirements, and ensures safe handling during injection.

f. Long-Term Durability

The cured foam resists hydrolysis, biological degradation, and chemical attack, maintaining its integrity for years under high water pressure.

These advantages make hydrophilic polyurethane grouting the most versatile and reliable leak-sealing material in today’s construction industry.

Typical Applications in Construction and Civil Engineering

Water-based hydrophilic polyurethane grouting is widely used across civil infrastructure and building waterproofing projects. Its ability to react and cure in the presence of water makes it suitable for active leaks and high-moisture environments.

Common Application Areas:

Basement Leak Sealing – Prevents water ingress through cold joints, expansion joints, and concrete cracks.
Tunnels and Subway Systems – Seals continuous seepage under high hydrostatic pressure.
Underground Parking Structures – Protects subgrade facilities from long-term moisture exposure.
Bridges and Expansion Joints – Provides flexible sealing against dynamic stress and movement.
Sewage and Water Retaining Structures – Ensures chemical resistance and waterproofing integrity.
Concrete Crack and Void Repair – Used for filling fine cracks, voids, and honeycombed concrete surfaces.

In all these applications, hydrophilic polyurethane grouting provides permanent leak sealing and extends the service life of reinforced concrete structures.

Comparison: Water-Based vs. Solvent-Based Polyurethane Grouting

Parameter	Water-Based Hydrophilic PU	Solvent-Based Hydrophobic PU
Expansion Type	Foam or gel (controlled swelling)	Dense foam, high expansion
Suitable Environment	Wet, active leaks	Dry or low-moisture environments
Elasticity	Flexible and re-swellable	Rigid and less elastic
Toxicity / VOC	Low / Non-toxic	Higher VOC content
Adhesion Strength	Excellent to concrete and rock	High but brittle under movement
Environmental Impact	Eco-friendly	Less eco-friendly

Analysis:

Water-based grouting systems are ideal for active water leaks and confined spaces where chemical safety and controlled expansion are crucial. Solvent-based systems, on the other hand, are better suited for dry crack sealing or heavy structural injection requiring high compressive strength.

Professional contractors often use a combination of both systems, depending on leak conditions and site requirements.

Grouting Process and Technical Construction Guidelines

Correct grouting procedures determine the success of leak sealing. Below is the recommended process followed by YURU Waterproof’s professional contractors:

First: Site Preparation

Identify the leakage source and determine the crack path.
Clean the surface and remove loose debris or oil.
Mark injection points along the crack line (spacing 15–30 cm).

Second: Drilling and Packer Installation

Drill holes at a 45° angle intersecting the crack at mid-depth.
Install mechanical or steel injection packers securely.

Third: Injection Process

Mix water-based PU grout thoroughly.
Inject material slowly using a high-pressure pump (0.3–0.6 MPa).
Monitor material flow and stop injection when backflow appears.

Fourth: Reaction and Curing

The material reacts upon contact with water, forming a flexible sealing foam or gel within 1–3 minutes (depending on formulation).

Last: Finishing

Remove packers after curing.
Seal surface openings with epoxy or cementitious patch material.
Perform leakage testing and inspection.

By following these steps, contractors can ensure complete crack penetration, stable expansion, and long-term waterproofing results.

Product Options from YURU Waterproof

YURU Waterproof offers a full range of polyurethane grouting materials designed to meet the needs of professional waterproofing contractors and engineering projects. All products are ISO 9001 and CE compliant, ensuring consistent performance and safety.

1. Water-Based Hydrophilic PU Grouting Material

Designed for sealing active water leaks in concrete structures.
Low viscosity for deep penetration.
Controlled reaction and expansion with excellent flexibility.

2. Oil-Based Hydrophobic PU Grouting

Best suited for dry cracks or large voids with limited water presence.
High compressive strength and water repellency.

3. PU Foam Grouting System

Expands rapidly to fill large voids or flowing leaks.
Ideal for quick repairs in tunnels and foundations.

4. Customized Formulations

Tailored formulations based on site-specific conditions such as temperature, viscosity, and reaction speed.
Available in bulk or OEM packaging for contractors and distributors.

All YURU Waterproof products undergo rigorous laboratory testing and field validation, ensuring reliable, consistent, and long-lasting leak-sealing performance.

Why Choose YURU Waterproof as Your Material Partner?

YURU Waterproof has been a trusted name in the construction waterproofing and grouting materials industry for over a decade.

Key Strengths:

20+ years of experience in polyurethane and injection grouting systems.
Independent R&D and production base with strict quality control.
OEM/ODM customization for international contractors and distributors.
Global export capability covering Asia, the Middle East, and Europe.
Technical support and field training for engineering projects.

With YURU Waterproof, contractors not only receive premium grouting materials but also comprehensive technical support, training, and logistics coordination—ensuring efficient project delivery and cost-effective solutions.

FAQs

What makes water-based hydrophilic polyurethane grouting unique?

It reacts directly with water, forming a flexible sealing gel that adapts to wet conditions and can re-swell when rehydrated.

Can it be used for active leaks?

Yes, hydrophilic PU grouting is ideal for active and continuous water leaks, including tunnels, basements, and foundations.

How long does the sealing effect last?

Properly applied, it offers over 10–15 years of waterproofing performance with minimal maintenance.

Is the material environmentally friendly?

Yes. It is a low-VOC, non-toxic, solvent-free formulation, safe for both applicators and the environment.

Does YURU Waterproof provide technical guidance?

Absolutely. YURU offers on-site training, material selection consultation, and project-based technical support.

Conclusion

Water-based hydrophilic polyurethane grouting is a modern, reliable, and environmentally responsible solution for leak sealing in concrete structures. Its unique chemical reactivity, strong adhesion, and ability to function under wet conditions make it indispensable for professional waterproofing contractors.

With YURU Waterproof’s advanced polyurethane grouting systems, you gain proven product reliability, technical expertise, and tailored project support—ensuring lasting waterproofing performance for your engineering needs.

YURU Waterproof – Building durable waterproof structures through science, precision, and performance.

Looking for a trusted polyurethane grouting supplier for your next project?

Contact YURU Waterproof for expert advice, customized formulations, and wholesale pricing.

YURU Product solutions

Request A Quote for Your Waterproofing and Grouting Projects!

*We respect your confidentiality and all information is protected.

Understanding Water-Based Hydrophilic Polyurethane Grouting for Leak Sealing

Introduction