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Aging concrete infrastructure such as water tanks, sewer systems, manholes, and storm water tunnels tend to exhibit a variety of problems including corrosion, cracking, sedimentation, and abrasion. These problems manifest as costly leaks and a frequent need for maintenance. Replacing these structures is not always practical or possible. Fortunately, concrete protection products can be used to rehabilitate functionality while also extending the service life of the structure.
In this article, we will discover how concrete protective liners (CPL) serve their purpose well as water tank liners. We will explore the common types of problems associated with aging water tanks, highlight the benefits of CPL and how it is well-suited to tackle those problems, and describe a specialized CPL product designed specifically for water tank rehabilitation.
Concrete: Porous and prone to degradation
The past century has revealed a weakness in the most ubiquitous building material in the world: Exposure to various media can affect performance and reduce the life expectancy of concrete structures. For instance, hydrogen sulfide gas (H2S) generated from anerobic decomposition can cause microbial corrosion when microorganisms convert the condensed H2S gas into sulfuric acid (H2SO4). Without proper protection, structures made with concrete will deteriorate over time, reducing the total service life.
Another extenuating factor is the increased concentration of corrosive substances in wastewater as a result of the introduction of low-flow fixtures in showers, toilets, and sinks. The increased concentrations over time have resulted in a greater frequency of corrosive attack and structural damage to concrete structures that come into contact with wastewater. Besides increasing corrosive concentrations, low-flow fixtures also increase the concentration of sediment deposits, which can collect in pipes and wastewater overflow tanks, reducing performance.
While potable water tanks do not come into contact with many of the media found in wastewater, they are still susceptible to degradation from leeching, carbonation, and chlorides. In addition, these structures are also susceptible to leakage. To prevent corrosion and degradation or exfiltration/infiltration, operators often add concrete protective coatings or liners to act as an impermeability layer between the concrete and the contained media.
Concrete protective liners (CPL)
Concrete protective liners can be made with a variety of materials. The type we will describe in this article is made with polyethylene, a thermoplastic that offers excellent chemical resistance (from pH 1.0 up to pH 14), durability, and flexibility. CPL are typically preferred over alternative products such as concrete protective coatings due to its improved thickness and strength, which enables CPL to function with a longer service life and with fewer maintenance requirements.
For modern constructions, designs typically include CPL from the start of the project and will even prefabricate the liner to suit the installation. Some of the largest water tanks have been constructed in recent years using these methods. Lusail City’s potable water storage tanks, for instance, each have a capacity of about 150,000 m3 and together help support up to 450,000 inhabitants. The planned city near Qatar will provide venues and more to support the 2022 FIFA World Cup. In total, about 40,000 m² of CPL were used in a nontraditional roll in this project to protect the concrete foundations of the water tanks against corrosive seawater and infiltration.
CPL’s flexibility and high elongation means that the liner can also bridge cracks in aging concrete structures. Using CPL, installers can rehabilitate old water tanks while also increasing their service life by protecting the concrete surfaces from aggressive media.
Hydroclick: A specialized water tank liner for rehabilitation
Hydroclick by AGRU is a specialized CPL with patented attachment profiles that can be used to snap the liner onto the structure walls and floors for fast, precise rehabilitation of potable water storage. The unique click studs, which can snap into place, as well as its weldability and ability to be prefabricated, enable rapid installation of HydroClick into existing water tanks. This rapid installation is critical for potable water tanks that cannot be left out of service for an extended duration.
Hydroclick is also easily cleaned and maintained and is an NSF 61 designated product, signaling its safety in all potable water systems. A summary of the benefits of Hydroclick includes the following:
- Rapid Installation
- Long Service Life
- Smooth Surface Minimizes Biological Growth
- Easy Cleaning
- Minimal Maintenance
- Complete Leakage Control
- Corrosion Resistant.