Galvanized Steel - Advantages to Achieving a Design with the Lowest Carbon Footprint

Hellen Christodoulou, Ph.D., Eng., B.C.L., LL.B., M.B.A.

Executive Vice President, Engineering, Sustainability and Business Development, CORBEC

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Keywords: Sustainable design, Sustainable Choices, Low-carbon footprint, Galvanization

Sustainable Construction, Circular Economy, Structural Design, Case Studies

Re-use & Re-Purpose, Global Warming Potential

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Abstract:

The new buzz word of the construction industry is “Sustainable Construction”.  Galvanized steel incorporated in the early design decisions provides short-term and long-term innovative solutions that optimize durability and facilitate circularity of steel structures. Galvanization puts circular economy policy into practice.

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This presentation will discuss how the structural impacts are positively affected by using galvanized steel and must be an important part of the Carbon in construction and an overview will be provided of the design applications and solutions that can reduce the global warming potential. Whether it is for transport systems, bridges, reinforcing rebars, infrastructure, housing, etc., galvanizing is an essential solution to meet and exceed design and lifespan expectations and contribute to sustainable design choices.

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Why galvanize? Case studies will outline effective design considerations for various applications and uses in structures, for efficacy, flexibility, robustness for reuse and repurposing.  The proper evaluation and use of Environmental Product Declarations when using galvanized steel is becoming even more relevant if we are to meet our global commitments. As a result, understanding and applying the proper considerations and weighing comparisons are a critical part of the design process. It’s all about thinking outside the box with facts as proof!

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INTRODUCTION

What is Hot-Dip Galvanizing?

Galvanizing involves dipping steel components into a bath of molten zinc, which forms a metallurgical bond with the steel substrate. The galvanizing process in principle is simple and it consists of three basic elements: surface preparation, galvanizing, and inspection. Handling projects properly requires expertise and quality assurance, and this depends on the provider, the facilities used, the crew and their level of knowledge. Even though the process requires energy for heating the zinc bath, it is considered the most energy-efficient compared to some other coating methods; its versatility and adaptability allows for a wide range of applications in various industries, including construction, transportation, infrastructure, and utilities.

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When we compare a galvanized coating on steel to a coating such as painting for example, galvanizing always takes the lead. It offers a highly durable and long-term protection against corrosion, typically lasting 75-100 years in interior, exterior, remote, and corrosive environments. As such galvanized steel requires minimal maintenance over its lifespan, reducing the need for frequent recoating or replacement, it delivers unparalleled performance over other corrosion protection methods. At its end-of-life it is recyclable.

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Painting as an alternative, which involves the application of liquid paint or powder coatings onto the steel surface, followed by curing or drying, is an energy-intensive manufacturing process. It does provide short span protection against corrosion but requires periodic maintenance (repainting) to maintain effectiveness in preventing corrosion and maintaining appearance. At its end-of-life, painted steel may be partially recycled.

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Just to bring context to the above, EGGA (European General Galvanizers Association) published a case study in one of their publications, showing the extensive cost and waste in maintaining the legendary Eiffel Tower in Paris.  Each repaint applies 60 tonnes of paint, while 15 to 20 tonnes of paint are eroded between each repaint, as the removal of all existing paint before repainting cannot be done without lengthy closures. Each repaint adds approximately 40 tonnes of paint, making the structure 700 tonnes heavier than its intended design. To do the work, 25 painters, wearing 1,500 sets of work gear and 1,000 pairs of leather gloves, relying on 50km of safety lines and 8000m2 of safety nets, 1,500 paint brushes and 5,000 abrasive discs are necessary. The most recent repaint price tag was close to 5.8 million dollars; repainting is considered as 14% of todays complete construction cost of the tower today.  This is an excellent example of how important it is that structures be designed without the need for maintenance.

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A study was conducted in 2014 by the VTT Technical Research Centre in Finland. It used a balcony as its subject to compare the environmental footprint between a hot-dip galvanized coating versus a two-coat zinc-epoxy/polyurethane paint for only a 60-year lifecycle. Once again, the results are astounding, as displayed in Table 1 below; clearly indicates the lower carbon footprint of Hot-Dip galvanizing when compared to paint.

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What Are Effective Design Considerations in Structures

Effective design considerations in structures require a holistic approach that prioritizes safety, functionality, sustainability, aesthetics, and cost-effectiveness. Some of the key considerations to ensure effective design in structures include:

• Safety and Structural Integrity: Ensure that the structure meets all relevant building codes, standards, and regulations to guarantee safety for occupants and users.

• Functionality and Usability: Design the structure to meet the functional requirements of its intended use, whether it's a residential, commercial, industrial, or an institutional building.

• Sustainability and Environmental Impact: Integrate sustainable design principles to minimize the environmental impact of the structure throughout its life cycle.

• Aesthetics and Architectural Expression: Create an aesthetically pleasing and visually appealing structure that enhances its surroundings and contributes positively to the built environment.

• Cost-effectiveness and Value Engineering: Value engineering exercises to optimize design solutions, maximize efficiency without compromising quality or performance, and achieving the best ROI (return on investment).

• Durability and Maintenance: Specify durable materials and construction methods to ensure the longevity of the structure and minimize maintenance requirements over time. Consider factors such as weather resistance, corrosion protection, and ease of cleaning and upkeep to reduce lifecycle costs and ensure long-term durability.

• Flexibility and Adaptability: Design the structure to accommodate future changes and adaptations, allowing for flexibility in use, occupancy, and spatial configurations. Incorporate modular components, adaptable layouts, and flexible infrastructure systems to support evolving needs and requirements over time.

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By considering these key factors in the design process, architects, engineers, and designers can create structures that are not only safe, functional, and sustainable but also visually captivating, cost-effective, and resilient to the challenges of the future.

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Principles of Low Carbon Structural Design

Designing structures with low-carbon principles involves minimizing the environmental impact associated with the manufacturing, construction, operation, and end-of-life phases of the structure at the core.  A building, a bridge or any type of infrastructure project is uniquely designed with a designated structural system and materials to satisfy the project scope. The carbon footprint is hence evaluated as the impact of the combined material quantities and their effects throughout all stages of the entire lifecycle. Design considerations and choices are evolving as the proper information is disseminated.

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For low-carbon structural designs, there are many key considerations, three of the most important are:

• Choosing the right materials and coatings that will result in the lowest carbon footprint and offer the best performance over the life of the structure, ex. recycled or reusable materials.

• Optimizing structural systems, by designing efficiently with a long-term vision, using less material while maintaining structural integrity. Consideration should be given to innovative structural solutions like modular construction, lightweight materials, and advanced structural analysis techniques to minimize material use and construction waste and maintain longevity.

• Conduct life cycle assessments to evaluate the true environmental impact of the structure from cradle to grave, including material extraction, manufacturing, construction, operation and maintenance, and disposal/recycling/re-use; for example, design for disassembly and incorporate materials that can be easily recycled or reused at the end of the structure's life to minimize waste and promote a circular economy.

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Embodied Carbon in Construction and Its Impacts Affecting Design Decisions

An Environmental Product Declaration (EPD) is defined as a Type III declaration by International Organization for Standardization (ISO) 14025. It is aimed to quantify environmental information on the life cycle of a product to facilitate comparisons between products fulfilling the same function. The EPD methodology is based on the ISO Life Cycle Assessment (LCA).

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A Lifecycle assessment (LCA) is intended to assess the environmental impacts of all stages of a products’ life from extraction of raw material (steel milling), processing, manufacturing, transport, construction, maintenance and disposal or recycling. It is misleading when industries publish their EPD’s which effectively compare materials only at the production stage. Limiting design decisions only to this stage, generally termed “cradle to gate” is unrealistic, since materials cannot be compared at this boundary A1 to A3, given their variations on their overall impact on the environment over the lifetime of the project. Cradle-to-gate LCAs are very limited, ignoring impacts during transport, construction, maintenance, disposal, and recycling and can therefore lead to nonsensical results.

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A “cradle-to-grave” LCA, includes all stages of boundaries A, B and C, providing a comprehensive analysis of resources used, and substances emitted through a product's entire lifecycle. The actual embodied carbon of all associated materials and construction processes is fully captured when all boundaries, A1 to C4 are considered. Only with this level of true assessment of a product’s impact, an informed design decision can be made. A designer’s long-term vision should be able to properly assess the environmental credentials and efficacy of materials and systems for the full lifecycle, to properly capture the full Global Warming Potential (GWP). The GWP is the contribution of emissions to the greenhouse effect (gases released), in the unit kg CO2-equivalent. Decisions should not have a restrictive reliance to just the life of a building, a bridge or infrastructure, but rather, to end-of-life disassembly, reuse and repurpose, beyond the landfill.

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The Advantages of Using Galvanized Steel in Early Design Decisions

Environmental considerations are becoming the predominant factors in design planning and evaluation and galvanizing is a sustainable process that is aligned with those objectives. It uses zinc, a naturally abundant material, and produces minimal waste. Its longevity reduces the need for frequent replacements, contributing to resource conservation and waste reduction.

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Galvanized steel undoubtedly offers numerous benefits which make it a preferred choice for a wide range of construction and infrastructure projects. It is primarily known for its durability and longevity, versatility, strength, and corrosion resistance properties, as follows:

• Longevity: The zinc coating on galvanized steel provides excellent protection against rust and corrosion, leading to a longer lifespan compared to untreated steel. This results in lower maintenance costs over the life of the structure.

• Versatility: Galvanized steel can be easily formed, welded, and fabricated, allowing for flexibility in design and construction. It can be used in a wide range of applications, from structural members to decorative elements.

• Strength: Galvanized steel retains the strength of steel while providing enhanced corrosion protection. This makes it suitable for structural applications where strength and durability are critical, such as in buildings, bridges, and infrastructure projects.

• Corrosion Resistance: Galvanized steel is coated with a layer of zinc, which acts as a sacrificial anode to protect the underlying steel from corrosion. This makes it particularly suitable for outdoor applications or environments with high moisture levels, such as marine environments or areas prone to industrial pollution.

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While the initial cost of galvanized steel may be slightly higher than untreated steel, its long-term durability, low maintenance requirements lead to serious cost savings over time. Furthermore, the prevention of rust and corrosion not only avoids costly repairs but prolongs the life and reduces the premature replacement of structures.

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Circularity in steel structures using galvanizing involves adopting practices that maximize the reuse, recycling, and recovery of materials throughout the life cycle of the structures. Galvanizing contributes to sustainable design by extending the lifespan of steel structures, eliminating maintenance, conserving resources, promoting end-of-life recyclability, and enhancing resilience and durability. By incorporating galvanized steel into projects, designers can create structures that are both environmentally responsible and economically viable for the long term. Some effective ways galvanization contributes to the circular economy include:

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• Resource Conservation: Galvanization extends the lifespan of steel products by protecting them from corrosion, thereby reducing the need for frequent replacements. This conserves natural resources by maximizing the utilization of materials and minimizing the consumption of virgin resources. In addition, galvanization is a relatively low-impact process that involves hot-dip coating steel with zinc, a naturally abundant material. The process produces minimal waste, and any zinc ash generated can be recycled or safely disposed of. By choosing galvanized steel, industries can reduce their environmental footprint and contribute to more sustainable manufacturing practices.

• Design for Disassembly: Galvanized steel can be incorporated into designs that prioritize disassembly and material recovery at the end of the product's life. By designing products with easy-to-disassemble components and using materials that can be separated and recycled efficiently, manufacturers can facilitate the recovery and reuse of valuable materials, closing the loop on resource utilization. Remanufacturing or refurbishing galvanized steel components and exploring innovative ways to integrate recycled materials into new products hence becomes the alternative.

• Structural Adaptation, Material Salvage, Reuse and Recycling: Repurposing an old, galvanized steel warehouse into a residential loft space or a commercial office building with minimal structural changes is considered a structural adaptation. This adaptive reuse preserves the embodied energy and materials of the original structure while giving it a new lease on life. Steel is one of the most recycled materials globally, and galvanized steel retains its properties even after recycling. At the end of its service life, galvanized steel can be easily recycled and used to manufacture new steel products without compromising quality. This promotes a closed-loop system where materials are continuously reused, reducing the demand for new raw materials, minimizing waste generation. Structural, salvageable components can be carefully removed and reused in new construction projects, ex. galvanized steel beams, columns, or trusses for use in other building projects, reducing the demand for new materials and minimizing potential waste. Galvanized steel structures can be modified or retrofitted to serve new purposes, including temporary structures and community projects.

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A Case Study as an Illustration: The 2017 Case study of a Netherland highway and their option to use re-galvanized guard rails. The results were stunning, showing that on average 67% of the components were intact and fit for re-use; they were cleaned stripped of the old galvanizing and re-galvanized. This decision to follow this simple procedure over 26,000 tonnes of CO2 was saved; putting it in context, this equals more than 8.3 million car kilometers.

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• Modular Construction: Galvanized steel components lend themselves well to modular construction techniques. Modular buildings, such as shipping container homes or modular office spaces, can be constructed using repurposed galvanized steel frames. Modular construction allows for efficient assembly and disassembly, making it easier to relocate or reconfigure structures as needed.

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Overall, an EPD for galvanized steel can provide valuable information about its environmental performance and sustainability benefits. By quantifying the environmental impacts of galvanized steel over its entire life cycle, the EPD can help stakeholders make informed decisions and support sustainable building practices. When comparing galvanizing with other coatings in terms of their carbon footprint, several factors need to be considered. These include the production process, the durability of the coating, maintenance requirements, and end-of-life considerations. For a lower carbon footprint, galvanizing offers advantages over other coatings due to its durability, minimal maintenance requirements, and recyclability. Since specific environmental impacts may vary depending on factors such as energy sources used in production, transportation distances, and end-of-life management practices. conducting a life cycle assessment (LCA) can provide a comprehensive comparison of different coating options in terms of their carbon footprint and overall environmental impact.

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An EPD declaration for galvanized steel can showcase:

• Resource efficiency by highlighting its long service life and minimal maintenance requirements compared to alternative materials.

• The reductions in greenhouse gas emissions, energy consumption, and resource depletion over the product's life cycle

• Galvanized steels’ support for sustainable material management practices

• An attestation of the elimination of maintenance and galvanized steel's contribution to sustainable building practices.

• Highlighting the environmental benefits by preventing corrosion and promoting environmental stewardship.

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Overall, an EPD for galvanized steel can provide valuable information about its environmental performance and sustainability benefits, by quantifying the environmental impacts of galvanized steel over its entire life cycle. Galvanization offers a very tough and abrasion resistant coating that leads to carbon efficiency. The zinc metallurgical bond in Hot-Dip galvanizing coated steel offers great cohesion as it makes the coating an integral part of the components. During transportation and handling, the outer zinc layer is shock absorbing, whereas the alloy layers beneath are more robust and offer the abrasion resistance. By embracing galvanized steel and adopting circular economy principles, industries can contribute to a more sustainable and resilient future.

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Conclusion

The goal moving forward is to strengthen collaboration and education among governments and building authorities, architects, engineers, contractors, and building owners to prioritize low-carbon design principles and share knowledge and best practices. Stakeholders must fully engage a long-term perspective to ensure the best return on their investment, as they realize the benefits of low-carbon design and protection systems and increase their participation in achieving their sustainability goals. Strategic planning, priority setting, product or process design or redesign are ultimately opportunities to improve the environmental performance of products at various points of their life cycle, and achieve an optimal performance of the entire project.

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So, why galvanize? The case is simple to make! Galvanizing is an important component when applying design considerations in various applications and uses in structures, for efficacy, flexibility, robustness for reuse and repurposing. Understanding the proper evaluation and use of Environmental Product Declarations (EPD’s) is key. When choosing galvanized steel, evaluating, and using the proper comparisons are a critical part of the design process, the prospective viability and resilience of the structure. The choices we make and the reasons for which we make them are becoming even more relevant, as we aim to collectively meet our global commitments.

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