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White Tank with Crystallizing Additive BETOCRETE-C
The "white tank" technology is one of the most popular waterproofing methods in Poland, yet it often suffers from a poor reputation. Why is this?
In Poland, there is no clear, unified definition for the term. Originating from Germany, the "white tank" concept has seen significant technological advances in concrete properties over the years. However, outdated guidelines from decades ago are still commonly used. On the Polish construction market, the white tank approach is often tailored individually by contractors based on their methods rather than standardized procedures. Importantly, "white tank" is not a regulatory term but rather a technological vision created by suppliers of coating-free waterproofing systems, including accessories for sealing construction joints.
What Is the Polish "White Tank"?
A "white tank" is a type of coating-free waterproofing. It is a monolithic reinforced concrete structure where the concrete itself acts as both the load-bearing component and the waterproofing layer. In Poland, this method typically uses "water-resistant" concrete with a W8 rating. However, this rating does not imply complete waterproofing but instead indicates a level of water permeability.
Understanding W8 Concrete
- The "W" factor in W8 denotes water tightness but does not mean the concrete is entirely impermeable.
- According to the Polish standard PN-88_B-06250, six concrete cubes measuring 15 cm each are tested for water resistance. Even if two out of six cubes allow full water penetration, the W8 rating is still considered valid.
- This raises questions about the reliability of using such a concrete mix in "white tank" designs.
Construction Challenges
The construction of a white tank is executed in phases, known as "pours" or "tacts." These phases are planned to induce controlled cracking in specified areas of the structure. Furthermore, a maximum allowable crack width is typically set (commonly 0.2 mm for water pressure, as per Eurocode 2 standards).
While this approach is well-intentioned, its implementation often relies on assumptions and outdated practices, leading to inconsistent results in waterproofing performance.
The Role of BETOCRETE-C
Using BETOCRETE-C crystallizing additives enhances the effectiveness of the white tank system. These additives:
- React with moisture to form insoluble crystals that seal micro-cracks and capillaries in the concrete.
- Improve long-term durability by maintaining structural waterproofing, even under hydrostatic pressure.
- Reduce the need for external coatings and repair interventions.
Advantages of the BETOCRETE-C White Tank System
- Integrated Waterproofing: Combines structural and waterproofing functions in a single concrete layer.
- Self-Healing Properties: Crystallizing additives repair minor cracks over time.
- Cost-Effective: Reduces dependency on external waterproofing materials and labor.
- Environmental Resistance: Performs well under aggressive conditions, including exposure to XA2-rated environments.
- Durability: Provides consistent protection against water ingress over the structure's lifespan.
Key Takeaways
The white tank method, particularly with the use of advanced additives like BETOCRETE-C, represents a modern, efficient approach to waterproofing. However, it requires precise execution, appropriate material selection, and adherence to updated guidelines to ensure long-term reliability. By addressing the shortcomings of outdated practices, this technology offers robust protection for critical structures such as foundations, basements, and water storage tanks.
Why Does the Polish "White Tank" Have a Bad Reputation?
The negative reputation of the "white tank" technology in Poland often stems from a lack of comprehensive knowledge among those responsible for its design and implementation. While this is not a universal issue, it frequently leads to the repetition of outdated solutions, which in turn results in complications during later stages of construction. Designers are well-versed in building structures; however, for many, the "white tank" simply represents concrete with a specific strength class. Practically speaking, they focus on the structural calculations and include safety factors. If the foundation interacts with water, they specify "water-resistant" concrete (W8) and consider the technology complete.
Misconceptions About W8 Concrete
It is important to clarify that W8 concrete is not fully waterproof. Additionally, the Polish standard PN-B-06265 no longer includes water-tightness grades. New projects should avoid referencing the "W" parameter, as it is no longer recognized in updated standards. Instead, the focus has shifted to measuring water penetration depth under hydrostatic pressure. This represents a significant change:
- The specifying parties and clients must agree on the maximum allowable depth of water penetration into the concrete, which should typically be less than the protective concrete cover's thickness.
Challenges in Modern Construction
There is a growing trend toward constructing buildings in more challenging terrains and at deeper levels. This has introduced more complex geotechnical and hydrogeological conditions. For example:
- Foundations are now being laid at levels -2 or -3, exposing them to aggressive physical and chemical factors.
- The absence of clear specifications for water resistance in the design phase often results in repeated mistakes, leading to structural degradation, particularly under demanding water-related conditions.
Risks Associated with "White Tank" Construction
The "white tank" is only as strong as its weakest link. Problems can arise at multiple stages:
- Design Phase:
- A separate "white tank" design is required in addition to the general construction plans, but few designers take on this task due to its complexity.
- Contractors often deviate from the original "white tank" design or create their own, increasing the risk of errors.
- Execution Phase:
- Concrete Pouring and Curing: Weather conditions and on-site practices heavily influence success. Improper curing—often dismissed as unnecessary by construction workers—can compromise the structure.
- Reinforcement and Interpretation: Errors in reinforcement placement or misreading the design can lead to structural weaknesses.
- Even high-quality concrete cannot compensate for mistakes in placement, curing, or reinforcement, leading to cracks and leaks.
High Technological Demands
Maintaining strict adherence to technological standards is critical for the success of "white tank" construction. Even minor deviations can compromise its watertightness. However, the technology does have one advantage: leaks are relatively easy to locate. For example:
- Water seeping from a corner clearly indicates the problem area, unlike systems with external waterproofing layers. In such cases, water can infiltrate between the coating and the concrete, meander within the structure, and emerge far from the actual source of the problem, making leaks challenging to locate.
Conclusion
The "white tank" technology offers significant potential when executed correctly but demands precision at every stage of the project. Ensuring proper design, execution, and maintenance is essential to prevent common issues and maximize the benefits of this advanced construction method.
Concrete with BETOCRETE-C Additive (Maximum Penetration Depth – 8 mm)
“White Tank” Technology on a Standard Foundation:
The Schomburg company offers its globally proven "White Tank" hydroisolation system using the BETOCRETE-C crystalline admixture. This admixture supports the self-healing process of shrinkage cracks in concrete, ensuring long-term structural integrity and watertightness.
Ease of Implementation with BETOCRETE-C:
The BETOCRETE-C system simplifies the process of designing and constructing "White Tanks" by providing a complete set of standards for project development.
The external side of the foundation is constructed using watertight concrete in the BETOCRETE-C system, with sealed construction joints at plate-wall, wall-wall, and plate-plate interfaces.
Advantages of the BETOCRETE-C System:
One of the key benefits of this solution lies in its compliance with Eurocode standards, which are stricter than Polish norms. Here's the comparison:
- Polish Norms: Allow for a design crack width of up to 0.3 mm, which can absorb water into the structure.
- Eurocode Standards: Limit the design crack width to 0.2 mm, effectively blocking water ingress.
This seemingly small difference has a significant impact on the durability and watertightness of the structure. Water entering cracks in a 0.3 mm system serves as a carrier for sulfates, CO₂, and chlorides, which can:
- Reach the reinforcing steel,
- Lower the pH of the surrounding concrete,
- Lead to steel depassivation, rapid corrosion, and eventual degradation or spalling of concrete structures.
The Science Behind BETOCRETE-C:
The Eurocode 2 (specifically, “Eurocode 2-- Design of Concrete Structures -- Part 3: Silos and Liquid Retaining Structures,” p. 10) explicitly limits crack widths to 0.2 mm for liquid retaining structures. Adopting this standard ensures significantly improved long-term performance and safety for "White Tank" applications.
BETOCRETE: A Comprehensive "White Tank" System Solution
