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Integral Waterproofing in Singapore

Integral waterproofing refers to the practice of adding waterproofing agents to the concrete mix itself, creating a homogeneous distribution that offers comprehensive protection against water penetration. This method is pivotal in constructing structures that are robust, durable, and resistant to the various deteriorative effects of moisture. This article delves into the fundamentals, benefits, methods, and applications of integral waterproofing in modern construction.

The Need for Waterproofing in Construction

Waterproofing is essential in construction to protect against water ingress that can cause severe structural damage such as steel corrosion, concrete deterioration, and mould growth. Traditionally, external waterproofing treatments like membranes and coatings were commonly used, but these solutions often address only the symptoms of water ingress rather than its cause.

What is Integral Waterproofing?

Integral waterproofing involves the addition of specific admixtures to the concrete mix, which disperses throughout the matrix, providing a comprehensive barrier against water penetration. These admixtures can be hydrophobic chemicals, which repel water, or hydrophilic materials, which swell in contact with water to seal cracks and voids.

Types of Integral Waterproofing Admixtures

Integral waterproofing agents are broadly classified into two categories:

  1. Hydrophobic Admixtures: These are typically composed of fatty acids, stearates, or other organic materials that repel water. They work by creating a physical barrier within the concrete that prevents water molecules from penetrating.
  2. Hydrophilic Admixtures: These include materials like crystalline and certain salts that react with water and cement particles to form insoluble crystalline structures. These crystals grow in the presence of water, effectively blocking and filling in the pores, capillaries, and hairline cracks within the concrete.

Benefits of Integral Waterproofing

  • Durability: By protecting the internal structure of the concrete from moisture penetration, integral waterproofing significantly enhances the longevity and durability of concrete structures.
  • Cost-effectiveness: Reduces the need for external waterproofing treatments and associated maintenance costs.
  • Simplicity: Simplifies construction processes by integrating waterproofing directly into the concrete mix, eliminating the need for additional layers or coatings post-construction.
  • Comprehensive Protection: Offers uniform protection throughout the concrete, not just at the surface, helping to prevent the ingress of water from any direction.

Application Techniques

The application of integral waterproofing begins at the batching plant where the admixture is added to the concrete mix. Proper mixing is crucial to ensure that the waterproofing agent is evenly distributed throughout the concrete. The concrete is then poured as usual, and the waterproofing properties develop as the concrete cures.

Case Study: The Use of Integral Waterproofing in the Gotthard Base Tunnel

Introduction to the Project

The Gotthard Base Tunnel in Switzerland, part of the New Railway Link through the Alps (NRLA) project, is the world’s longest and deepest railway tunnel. Stretching over 57 kilometers and reaching depths of up to 2,300 meters below the mountains, the tunnel presents a formidable challenge in terms of engineering and waterproofing.

Technical Challenges

One of the significant challenges was managing the high hydrostatic pressure due to the tunnel’s depth and the presence of large volumes of mountain water. The water pressure, combined with the tunnel’s extensive length, necessitated a robust waterproofing solution that could endure the harsh conditions without failure.

Integral Waterproofing Solution

For this project, a specialized integral waterproofing admixture was used, designed to provide comprehensive protection. This admixture needed to perform several functions:

  1. Hydrophobic Properties: To repel water and prevent water ingress into the concrete structure.
  2. Crystalline Capabilities: To seal micro-cracks and capillaries within the concrete, ensuring that any potential pathways for water leakage were effectively blocked.

Application Process

The admixture was added during the concrete batching process to ensure a homogeneous mix. The concrete was then used in the tunnel lining, where precision in application was critical due to the high pressures and the need for durability. The implementation involved advanced mixing technology and rigorous quality control measures to maintain consistency across the vast structure.

Outcomes and Performance

Post-construction assessments indicated that the integral waterproofing was highly effective. Monitoring over several years showed minimal water ingress, demonstrating the durability and efficacy of the admixture under extreme conditions. The tunnel’s structural integrity remained intact, with no significant maintenance issues related to water leakage.

Technical Innovations and Lessons Learned

The success of the Gotthard Base Tunnel’s waterproofing strategy offered several insights:

  • Importance of Admixture Quality: High-quality admixtures are crucial for ensuring the longevity and effectiveness of waterproofing in large-scale infrastructure.
  • Preventive Approach: Integral waterproofing provides a preventive approach to moisture control, addressing potential water ingress at the source by modifying the concrete’s properties.
  • Cost-Effectiveness: Despite the initial higher costs of integral waterproofing admixtures, the reduction in maintenance and repair costs over the tunnel’s lifespan validated the investment.


The Gotthard Base Tunnel serves as a benchmark for modern tunnel construction and highlights the critical role of integral waterproofing in managing environmental challenges. This case study underscores the potential for integral waterproofing solutions to enhance the durability and performance of infrastructure in demanding environments.


Integral waterproofing is a forward-thinking approach that embeds durability and resistance directly into the concrete. As construction technologies advance, the adoption of integral waterproofing is set to increase, driven by its undeniable benefits in enhancing the structural integrity and longevity of buildings. By understanding and implementing this method, industry professionals can significantly uplift the quality and durability of their projects.