Reuse of Steel Sheet Piles - Best Practice

François Fohl and Oliver Hechler

Abstract 

 

Steel sheet piles are used for retaining walls. Due to their modularity, they can be easily installed and extracted after their service life. 

After their first use, they can be either directly recycled or reused several times and then recycled. The reuse of steel sheet piles allows to avoid new production and thus CO2-emissions for their production, reducing the environmental impacts per use. 

In temporary works, like construction pits, the reuse of sheet piles is common practice. Also, for certain permanent projects, there is no disadvantage in using second-hand sheet piles. 

This article shows, on the basis of two case studies the best practice for reuse of sheet piles. The environmental impacts for a temporary project in Germany are discussed based on a Life Cycle Assessment for the sheet piling tonnage. Over the life cycle of the steel, 1 535 t of CO2-eq are emitted. 

Reuse of the sections saved 79% of greenhouse gases. For a dyke reinforcement in the Netherlands, the project owner partly chose second-hand sheet piles to reduce the environmental impacts of the infrastructure project. 

Keywords: Steel, Sheetpiles, Reuse, Environmentalimpacts

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Introduction 

 

Steel sheet piles are widely used in infrastructure applications. Functioning mainly as a retaining wall, they are found for example in quay walls, cofferdams, bridge abutments, underground car parks or temporary pits. 

Steel sheet piles are sections that are driven into the ground and are connected over interlocks (or clutches), to form a continuous wall. There is a wide variety of sections, but U- and Z-piles are the most common. Common widths for one sheet pile (one module) are ranging from 600 to 800 mm. 

Steel sheet piles are completely impervious, an infiltration of water through a sheet pile wall is only possible along the interlocks. Due to the tight shape of the interlocks of type ‘Larssen’, a high seepage resistance is already given for ArcelorMittal sheet piles. 

For applications with high requirements to watertightness, like cut-off walls for contaminated sites, several sealant systems are available. Welding of the interlocks can provide complete watertightness. 

The durability of steel sheet piles is well documented. Unprotected steel in the atmosphere, water or soil is subject to corrosion. However, based on the life-time requirements for the steel structure, the integrity can be assured by several methods. 

‘Sacrifical steel’ to build a structural design reserve is common, but the corrosion process can also be limited by coatings, low-corrosion steel grades, cathodic protection and others. Corrosion rates for steel sheet piles for all relevant environments are well documented in Eurocode 5 - Part 5. 

Sheet pile structures can be easily dimensioned for 50-100 years lifetime depending on the application. Steel sheet piles are prefabricated products, hence very efficient in installation due to their modular system.

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