Editor’s Note: This post, originally published on March 5, 2020, has been thoroughly revised and updated to ensure accuracy and comprehensiveness.
Leakmaster® Hydrophilic Sealant Waterstop for Concrete Joints and Penetrations
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Not every waterproofing challenge can be solved with a preformed waterstop. Pipe penetrations, irregular construction joints and complex concrete details may require a gun-applied waterproofing solution that can conform to uneven surfaces and confined details.
A gun-grade hydrophilic polyurethane waterstop can provide a practical solution for these situations. Applied as a continuous bead, it expands when exposed to water to help seal confined joints and penetrations that are difficult to protect using conventional waterproofing products.
This guide explains how Leakmaster® works, where it is most effective and how it complements other hydrophilic waterproofing solutions to help create a complete waterproofing system. If you’re looking for broader guidance on protecting below-ground concrete structures, start with our Waterproofing Concrete Foundations guide.
What is Leakmaster Hydrophilic Waterstop?
Leakmaster®, is a one-component, gun-grade hydrophilic polyurethane waterstop designed to waterproof irregular construction joints, pipe penetrations and other confined concrete details where preformed profile waterstops are difficult to install.
Unlike exposed waterproof sealants designed to weatherproof external joints, Leakmaster® is installed within the concrete detail before placement. Once confined by the surrounding concrete, it reacts to water by expanding and developing sealing pressure within the joint.
Its gun-grade formulation makes it particularly suitable for applications where preformed waterstop profiles may be difficult to install, allowing contractors to create a continuous seal around irregular shapes and complex junctions.
How Does Leakmaster® Work?
Leakmaster® protects concrete joints through a simple hydrophilic reaction that occurs after installation.
The process follows four key stages:
- Apply a continuous bead to the prepared construction joint, penetration or concrete detail.
- Position the material correctly so it becomes fully confined once the concrete is placed.
- When exposed to water, the hydrophilic polyurethane begins to expand.
- The expansion develops sealing pressure within the confined joint, helping reduce the risk of water ingress.
Leakmaster® is designed to function within a confined concrete detail, where its water-swelling behaviour develops sealing pressure to help limit water ingress.
Where Is Leakmaster® Used?
Leakmaster® is best suited to construction details where irregular geometry makes preformed waterstops difficult to install. Its gun-grade application allows the material to follow complex shapes while allowing a continuous bead to be applied through the detail.
Typical applications include:
- Irregular Construction Joints – Construction joints with uneven profiles or difficult access can be sealed using a continuous bead of Leakmaster®, helping provide continuous sealing through the joint detail where profile waterstops may be difficult to position.
- Pipe and Service Penetrations – Where pipes and conduits interrupt the continuity of the concrete, Leakmaster® can be applied around selected penetration details where a gun-applied water-swelling seal is appropriate, helping reduce potential pathways for water ingress.
- Uneven Concrete Surfaces – Where construction joints or interfaces contain rough or irregular concrete surfaces, the gun-grade formulation conforms more easily than rigid preformed profiles.
- Complex Junctions and Transitions – Corners, changes in direction and intersecting concrete elements can create complex waterproofing details where a gun-applied material may be easier to install than a preformed profile. Leakmaster® allows continuous application through these complex areas without extensive cutting or shaping.
- Local Waterproofing Details – Leakmaster® is also suitable for isolated waterproofing details where only a small section of a structure requires treatment, making it a practical solution for localised construction joint sealing.
Key Benefits of Leakmaster®
Leakmaster® is designed to simplify waterproofing in areas where conventional profile waterstops may not provide the most practical installation method.
Key benefits include:
- Conforms to irregular geometry, making it easier to waterproof complex concrete details.
- Continuous bead application around penetrations and uneven joints without extensive cutting or shaping.
- Expands when exposed to water, helping develop sealing pressure within confined concrete joints.
- Strong adhesion to prepared concrete surfaces for reliable installation.
- Complements preformed hydrophilic waterstops, allowing different waterproofing solutions to be combined within the same project where required.
Rather than replacing profile waterstops, Leakmaster® provides an alternative for selected construction details where a gun-applied water-swelling material is more practical than a preformed profile.
Choosing the Right Waterproofing Solution
Water can enter a concrete structure through several different pathways, and each requires a specific waterproofing approach. Before selecting an individual product, it’s important to identify where the risk of water ingress exists and choose the waterproofing method designed for that construction detail.
The infographic below provides an overview of the major waterproofing solution categories covered throughout Danterr’s waterproofing guides.
Selecting Leakmaster® for Your Project
Leakmaster® is best suited to projects where irregular geometry or confined spaces make preformed waterstops difficult to install. Its gun-grade formulation allows contractors to apply a continuous bead around details that would otherwise require extensive cutting or shaping.
Leakmaster® is commonly selected for:
- Pipe and service penetrations through concrete walls and slabs.
- Irregular construction joints where a preformed profile is difficult or impractical to install.
- Corners, transitions and intersecting concrete elements.
- Local waterproofing details within larger structures.
- Areas where a continuous bead provides a simpler installation method than strip waterstops.
Rather than replacing Hydrotite or Polybar+, Leakmaster® complements these products by providing a practical solution for details where profile waterstops are less suitable.
Key Application Considerations
Correct installation is essential to achieve reliable waterproofing performance.
For best results:
- Apply Leakmaster® to a clean, sound substrate free from dust, laitance and contaminants.
- Apply a continuous, uninterrupted bead along the specified waterproofing detail.
- Position the material so it will be fully confined once concrete is placed.
- Protect the applied material from damage and site conditions that could affect the installation before concrete placement, in accordance with the current Technical Data Sheet.
- Follow the current Technical Data Sheet for complete installation requirements and project-specific recommendations.
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Supporting Durable Waterproofing Details
Correctly detailed construction joints and penetrations are important to the durability of below-ground and water-retaining concrete structures. Leakmaster® can form part of the waterproofing strategy by providing a water-swelling seal in selected confined joints, penetrations and irregular concrete details.
Product selection, substrate preparation, installation and confinement should follow the current technical documentation and project requirements to achieve the intended waterproofing performance.
Proven in Australian Infrastructure
Leakmaster® has been supplied for Australian water infrastructure projects involving waterproofing of selected concrete joints and detailing.
Verified applications include:
- Sydney Water’s Upper South Creek Advanced Water Recycling Centre – Leakmaster® was specified as part of the waterproofing system for selected concrete detailing within the project. This application demonstrates its suitability for complex water infrastructure where reliable sealing of confined details is required.
- Tolosa Water Supply Upgrade – Leakmaster® was used as part of the project’s waterproofing strategy for selected concrete construction details.
These project examples reflect Leakmaster® applications within broader concrete waterproofing strategies involving selected joints and construction details.
Conclusion
Waterproofing complex concrete details requires more than selecting a general-purpose sealant. Pipe penetrations, irregular construction joints and difficult interfaces may require a waterproofing material that can conform to complex geometry during installation.
As a one-component, gun-grade hydrophilic polyurethane waterstop, Leakmaster® provides a practical solution for these applications. Its ability to follow irregular surfaces and expand when exposed to water makes it a practical component within a broader waterproofing system, particularly where preformed waterstops are not the most practical option.
Selecting the right waterproofing solution starts with understanding the construction detail you’re protecting. In some projects, different waterproofing components may be used together to address construction joints, penetrations and other water-ingress risks according to the project design.
Speak With Danterr
Every project has different waterproofing requirements. Whether you’re sealing pipe penetrations, construction joints or complex concrete details, Danterr can help you identify the most appropriate waterproofing solution for your application.
Contact our technical team for product selection advice or explore our range of hydrophilic waterproofing systems to support your project’s waterproofing requirements.
Frequently Asked Questions:
A hydrophilic polyurethane waterstop is a moisture-activated waterproofing material used to seal construction joints, pipe penetrations and other confined concrete details. When exposed to water, it expands within the confined detail to develop sealing pressure and help limit water ingress.
Leakmaster works by expanding when it comes into contact with water. This allows it to fill gaps and voids in construction joints, forming a watertight seal. The polyurethane-based composition ensures that once cured, the seal is flexible, durable, and capable of withstanding environmental stress and movement in the structure.
Leakmaster® is best suited to irregular construction joints, pipe penetrations, uneven concrete surfaces and complex junctions where preformed hydrophilic waterstops may be difficult to install. For straight construction joints, preformed profile waterstops such as Hydrotite® or Polybar® may be a more appropriate solution.
Leakmaster is applied as a continuous bead within the concrete detail before placement. Once confined by the surrounding concrete, it expands when exposed to water, creating sealing pressure that helps reduce water travelling through joints and penetrations.
Yes. Leakmaster® may be used alongside other waterproofing solutions where different construction details require different sealing methods.
Yes, Leakmaster is often used alongside other waterproofing solutions as part of a complete waterproofing strategy. For example, Hydrotite® or Polybar+® may be specified for straight construction joints, while Leakmaster® is used around penetrations or complex concrete details where a gun-applied solution is more suitable for the detail.
Leakmaster contributes to environmentally friendly construction practices by preventing water leaks and reducing water waste. This aligns with Danterr’s commitment to sustainability. By providing a reliable seal, Leakmaster minimises the need for frequent repairs and replacements, which in turn reduces the consumption of materials and resources, supporting greener construction methods.
For reliable waterproofing performance, Leakmaster® should be applied to a clean, prepared substrate as a continuous bead and positioned so it becomes fully confined after concrete placement. Installation should always follow the current Technical Data Sheet and project specifications.
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