Understanding Corrosion & Material Compatibility

When specifying materials for buildings, it is important to consider correct materials to ensure longevity of the structure. Building designers, architects and engineers often have an understanding of material compatibility, however this can can get lost as the project moves from the design stage to construction stages. This can result in the use of incompatible materials or incorrect maintenance practices that can potentially harm the integrity of the building, leading to costly repairs and impact the long term performance of the structure.

Corrosion costs the Australian economy an estimated $78 billion annually (according to the Australasian Corrosion Association). Corrosion is the process where materials break down due to chemical reactions, showing as rust or stains. Factors such as surrounding envionment, exposure to chemicals or types of materials affect how corrosion occurs. To help mitigate the risk of corrosion in projects, selecting suitable materials for the specific environment is crucial. Materials must be chosen with durability and purpose in mind.

Corrosion is the progressive deterioration of a material’s characteristics, mostly resulting from its interaction with the surrounding environment. This can affect nearly all material types, making it an inevitable challenge in the built environment. Corrosion compromises not only the structural integrity but also aesthetics and function of materials.

The most common form of corrosion is electrochemical oxidation, which occurs when the material reacts with an oxidant such as oxygen. In metallic materials, this reaction often leads to the formation of oxides or salts derived from the original metal. Rust is an example of this, which visibly forms red/orange oxides that visibly alters the materials surface.

The type of corrosion that can form on a surface depends on the environment, physical and chemical properties of the material. Understanding common corrosion forms is essential for the selection of appropriate materials for a project.

Corrosion is affected by several factors, which can be grouped into categories like material compatibility, environmental conditions, maintenance practices, design considerations, and insufficient protective measures. Recognizing these causes is vital for preventing material degradation and maintaining long-term durability.

Material compatibility refers to the capacity of various materials in a system or structure to work together without promoting or speeding up corrosion. Ensuring that materials are compatible is key to avoiding harmful chemical, electrochemical, or environmental reactions that can weaken them and affect their functionality. This concept is particularly important in settings where moisture, chemicals, or temperature changes are common, as these factors can heighten corrosion risks. 

Selecting the right materials is vital for ensuring structural strength, minimizing maintenance, and prolonging the lifespan of the system. In critical areas like building facades, drainage systems, and fasteners, even slight mismatches in materials can lead to serious long-term complications. By focusing on material compatibility during the design and construction stages, professionals can develop systems that operate reliably and sustainably over time.

A material compatibility chart can be used to determine how different materials interact when exposed to specific environmental conditions. There are a variety of material compatibility charts available online that focus on different materials and chemical processes.

To effectively reduce the risk of corrosion in built environments, it’s essential to adopt design strategies that surpass basic compliance with standards and regulations. While the Australian Standards and the National Construction Code offer vital guidance, merely meeting the minimum criteria won’t yield the best long-term results. By going beyond these benchmarks, we can significantly enhance durability and performance over time. 

Choosing materials that are suited to specific environmental conditions is critical. In challenging settings, such as marine environments, it’s important to use corrosion-resistant materials like stainless steel, aluminum, or coated metals. Components and fasteners should be made from the same or compatible materials to reduce the risk of galvanic corrosion; it’s advisable to avoid pairing highly dissimilar metals, like copper with aluminum or steel. 

Off-the-shelf solutions may not always meet the needs; thus, materials should be selected with a focus on environmental resilience and purpose. Effective protective coatings—such as paint, galvanization, or powder coating—act as barriers against corrosive elements. Additionally, designs must emphasize moisture control by implementing features like proper drainage systems and avoiding crevices or tight spaces where water might accumulate. It’s crucial to prevent direct contact between metals and porous materials, such as wood or plaster, without suitable protective measures since these can hold moisture and worsen corrosion. 

Implementing efficient drainage and waterproofing systems is key to preventing standing water, a primary cause of corrosion. This may involve creating sloped surfaces, designated drainage routes, and waterproof seals in areas prone to moisture. Moreover, ensuring that structures are designed for easy access—with features like removable panels or inspection ports—facilitates regular maintenance and cleaning.