Why vitrified clay pipes are reclaiming their place in modern infrastructure

The construction industry is undergoing a shift as more specifiers and their clients move back to time-tested materials. Vitrified clay pipes demonstrate this process in action.

Independent Life Cycle Assessment data demonstrates that when evaluated across the complete operational lifespan of infrastructure projects — typically spanning 50 to 100 years — vitrified clay pipes emerge as the superior economic choice.

The assessment methodology considers multiple cost factors often overlooked in traditional procurement decisions: maintenance frequency, replacement cycles, energy consumption during manufacturing, transportation impacts and end-of-life disposal costs.

Vitrified clay pipes consistently outperform when these metrics are applied, delivering substantial long-term savings. These economic advantages become even more pronounced in challenging environments such as wastewater and industrial projects where chemical resistance and structural integrity of vitrified clay make all the difference.

The methodology of Life Cycle Costing (LCC), which evaluates the total costs associated with a product or system over its entire lifecycle, is gaining momentum as the industry looks for future-proofed systems.

A recent study by Project Hub 360 mapped the full lifecycle costs of vitrified clay pipes compared to thermoplastic alternatives for drainage and wastewater applications over a 150-year horizon.

Based on a completed project in Val Tinella, Italy, the analysis revealed that while the initial investment for vitrified clay pipes was €3,317,882 compared to €3,188,377 for polypropylene (+4%), the long-term savings achieved through reduced maintenance and replacement costs make vitrified clay the superior choice for utility companies looking to future-proof their sewer investments.

The independent LCC research also confirmed that if the operational lifespan exceeds 40 years, which is the case with the vast majority of sewer systems, vitrified clay pipes are the best investment from an economic standpoint. They offer cost savings of up to 65% in the long run compared to alternative materials. As the UK water industry looks for better lifetime value, adopting an LCC approach to product choice will help avoid future costs and enhance the sustainability of sewer infrastructure.

The sustainability credentials of vitrified clay pipes are another reason why specifiers are returning to the material. These are founded on its simple composition — just three natural materials are used to make them: clay, chamotte and water; all of which are available in virtually unlimited abundance.

Locally sourced clay is the primary component, dramatically reducing transportation-related carbon emissions. The second element, chamotte, improves the material’s properties by adding a skeleton-like structure to the clay, which helps prevent shrinkage and cracking during firing. When fired at high temperatures, the clay vitrifies, resulting in a dense, chemically resistant and long-lasting pipe. These three ingredients eliminate the need for synthetic polymers, plasticisers and chemical stabilisers, making the manufactured product completely inert.

Strength is also a characteristic to consider; our pipes offer longitudinal compression resistance as high as 100N/mm2, which makes them an excellent choice when ground loading has to be factored in. In terms of stability of the product, the material is suitable for use in either alkaline or acidic soils making them suitable for brownfield sites and reclaimed land.

When specifying the product, the relevant standard is EN 295. This standard specifies requirements for vitrified clay pipes, fittings, and flexible joints.

The circular economy principles are naturally embedded in clay pipe production. At the end of their exceptionally long service life of well over 150 years, they can be crushed and recycled as aggregate for construction applications or returned to ceramic manufacturing processes, creating a truly sustainable material cycle.

Steinzeug-Keramo’s vitrified clay pipes contain at least 30% recycled content, supporting the circular economy by minimising waste, extending product life cycles and promoting the reuse of valuable resources.

Since vitrified clay pipes do not contain any plastics or harmful substances, they can be left in the ground without leaching chemicals or microplastics into the surrounding soil or water. This makes them a safe and environmentally responsible choice for long-term underground use.

Lange Street in Detmold, one of Germany’s most beautiful shopping streets, recently underwent a comprehensive redesign and wastewater system upgrade, including new combined sewer and stormwater drainage systems.

We supplied vitrified clay pipes for the construction of the underground wastewater infrastructure. They were specified due to the natural composition of the pipes: they do not lose strength or degrade over time when exposed to chemicals often found in sewer systems, such as hydrogen sulphide and are ideally suited for gravity-fed networks.

The three-phase construction began with a 155-metre section, using open-cut trenching with a gravel foundation to ensure stable pipe installation. Despite the road being only 15 metres wide, half remained in use to maintain access to shops and outdoor dining.

Due to limited space and deep trenches, logistics required precise coordination. We proposed dual infrastructure for stormwater and combined sewage to improve efficient water management and reduce overflow risks. The vitrified clay pipes met the project’s high demands, particularly in load-bearing capacity and durability.

One distinctive feature of Detmold’s wastewater system is that the existing combined sewer, constructed in brickwork, was four metres below the surface, while the stormwater sewer was located at a depth of two metres.

The open-cut trench was both narrow and deep, making it impossible for construction vehicles to access. Therefore, the gravel bed was created first, followed by the precise installation of the vitrified clay pipes.

The pipes will provide a long-term sustainable solution for the city, as they won’t corrode, degrade or lose strength over time. Since they contain no harmful substances, they can remain in the ground without risk of polluting the surroundings and even outlive the surrounding infrastructure with lifespans exceeding 150 years.

As the construction sector looks for better long-term value, adopting an LCC approach to product choice will help avoid unexpected expenses and enhance the sustainability of sewer infrastructure. By integrating LCC methodology into decision-making processes, developers, specifiers and their clients can make informed choices that ensure maximum value from their investments.

This article appears in the AT Journal issue 156, Winter 2025 as "Why vitrified clay pipes are reclaiming their place in modern infrastructure" and was written by Leon Woods, Country Manager UK, Steinzeug-Keramo Group.

--CIAT