The Benefits of Using Geopolymer Pipe Lining for Stormwater Management System Repairs
Rainy waters pipes and culverts (pipes) serve a valuable function in the underground infrastructure of a community. Not only are they an essential part of ensuring excess runoff is reliably drained from impervious surfaces such as paved streets, parking lots, pathways and sidewalks, but they also play a crucial role in the stormwater management system. By allowing runoff to be transported underground, stormwater pipes and culverts eliminate the safety hazards and damage that standing, running water can cause by staying above ground level.
In addition to directing stormwater flow, stormwater pipes help cities and local governments control erosion. Proper erosion management and control is essential to prevent potentially catastrophic damage to commercial and residential structures, roads and other infrastructure, protecting families who live, work and play in communities. For many, seeing dirt deposited on a road is a cause for concern, but for those who work in the stormwater industry, it is much more concerning when dirt is generated by erosion around pipes, channels, embankments and other stormwater control features. To prevent dangerous erosion that can lead to devastating loss of the very infrastructure upon which stormwater control relies, it is essential to properly maintain stormwater channeling systems to ensure proper flow and structural integrity. .
For rainwater drainage applications, corrugated metal pipe (CMP) remains the material of choice for Departments of Transportation (DOT), utilities, and municipalities due to its low cost, expected life, and ease of placement on field. While these are significant benefits, CMP can pose a few challenges in some environments – potential for corrosion, staggered joints, and difficult sediment removal.
Fortunately, there are pipe lining methods available today that restore structural integrity and eliminate the causes of soil erosion and subsidence for greater longevity and performance, thereby maximizing cities’ investment in the pipelines. Each pipeline rehabilitation The method offers distinct advantages and disadvantages depending on each particular project.
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Stormwater Rehabilitation Options
Inverted pipe repairs using only spray or trowel applied mortars are a temporary fix that can present the appearance of a structurally restored pipe. However, this is not the case unless the existing CMP is structurally linked to the newly placed reverse liner, which adds considerable cost to the project. Failure to follow this critical step can result in serious defects including ovality, joint separation, and continued structural degradation of the pipe or culvert. It is better monolithically align host pipeeliminating the potential for defects and soil loss on the outside of the pipe.
While sliplining protects the hydraulic capacity of a pipe, it greatly reduces the overall dimension of a pipe. When a large amount of diameter is lost, a pipe can become difficult to inspect and maintain. In addition, large debris can become trapped in the pipe, increasing the possibility of buildup and interruption of flow, which ultimately creates hydraulic restriction. Sliplining often requires costly access and laying areas to merge and pull the new pipe into the host pipe, which must be restored at the end of the project.
Cured-in-place pipe (CIPP) offers a tight-fitting alternative with a relatively thin liner cross-section, but is not ideal for CMP rehabilitation projects as it is expensive for large pipes and is unable to adhere completely to corrugated sections, which leads to sag in the remaining annular space. CIPP may also restrict access to CMP culverts located on embankments or off-road.
Plastic-based coatings are also not suitable for this application because the material is susceptible to natural and man-made fires, which have increased in rural and urban settings as a result of climate change and homeless populations increasingly using the storm water pipes for shelter.
Although traditional and hybrid cement mortar products are often used for pipe rehabilitation, they lack adequate abrasion resistance to prevent degradation from recurring and are prone to cracking.
Given the complexity of CMP repairs and the limitations of current repair options, geopolymer mortar pipe rehabilitation is a growing best practice for the restoration of stormwater pipes greater than 36 inches in diameter. Geopolymer mortars excel where traditional cements, expensive composite systems (cement + epoxy) and other rehabilitation methods fail. Unlike traditional cement mortars that bond to aggregates, geopolymers use an alkaline liquid, such as water, and an alumino-silicate precursor to create a catalyst to initiate a polycondensation chemical reaction that forms an amorphous bonded network by covalence. This reaction gives high initial strength as well as long term physical benefits.
Spray application of geopolymers is well suited for CMP repair work. A spin-cast or hand-sprayed geopolymer mortar lining system constructs a new pipe using the host pipe as a base, removing annular space while plugging holes to yield a strong closed pipe with full structural value – eliminating the need for traditional excavation and replacement. This provides the flexibility to maintain the corrugations for a slower flow that is beneficial to wildlife or fill in the corrugations for a smooth end pipe that improves transportation and maintenance.
Geopolymer pipe rehabilitation has minimal disruption to the surrounding community and can be completed quickly with a minimal footprint. It maintains cross sections, allowing it to completely replace the host pipe structurally, while maintaining or increasing hydraulic capacity. This material also offers superior abrasion, chemical and heat resistance that withstands abrasive fluxes, de-icing salts, salt water and man-made spills and fires, providing decades of durability. structural and performance integrity.
The experience of a Department of Transportation (DOT) in New England illustrates the benefits of using geopolymer mortar lining for pipe rehabilitation. A 210-linear-foot, 90-inch-diameter CMP storm culvert installed under a major highway decades ago showed severe deterioration marked by several missing pipe sections. The pavement above had begun to settle, increasing the risk of collapse. Over the course of a week, the culvert was thoroughly cleaned and major repairs were carried out. Quadex GeoKrete geopolymer mortar and reinforcing mesh were used to repair the missing pieces of pipe. To complete the rehabilitation, a two inch thickness of GeoKrete was precision molded to create a new, stronger, abrasion resistant and more durable pipe that protected the integrity of the pavement; excavation was not necessary.
Ensuring the integrity of stormwater pipes and minimizing the effects of erosion no longer requires time-consuming and disruptive pipe replacement. Geopolymer pipe liner offers fast, low-profile installation, the flexibility to create a smooth or corrugated finish, and superior strength and longevity. It is an ideal choice for repairing stormwater management systems for optimal transport and prevention of soil erosion and subsidence.