Coastal events like the tragic collapse of the Champlain Towers condominium complex in Florida are increasing the spotlight on structure safety. According to researchers in the Department of Ocean Engineering at Texas A&M University (College Station, Texas, USA), saline-rich and humid environments are hazardous to building materials and can cause them to corrode and break down over time. As waters rise, coastal structures are put at greater risk.
Assistant professor Marcelo Paredes wants to bridge the gap between ocean engineering and materials science with his research developing corrosion-resistant high entropy alloys (HEAs) and materials modeling. “Until we find or discover new materials that are able to withstand these very aggressive environments, structural engineers are going to have to continue to face the possibility of the types of accidents seen in Miami,” he says.
One possible solution, according to the university, is Paredes’ corrosion-resistant high entropy alloys. While not ready for commercialization, these alloys offer a glimpse into the future of coastal engineering as they combine five or more elements in near equal parts to create a material with enhanced qualities.
“The idea is that you have a super material,” Paredes says. “Lightweight, durable, and resistant, not only regarding mechanical loads but also against environmental stressors. Now, we must make these materials affordable to manufacture.” Paredes notes that little is currently known about the corrosion-resistance properties of HEAs, and researchers are aiming to quantify the desired mechanical and chemical properties.
By developing these materials and investigating the factors affecting material performance, researchers are providing engineers with tools to better understand the physical and mechanical processes that building materials undergo, as well as how it impacts the health of coastal structures.
When buildings are constructed, their frames are often made out of reinforced concrete and steel, Paredes explains. This is usually achieved by embedding steel bars inside the concrete to give it extra strength. But along the coast, cracks and spalling (chipping and flaking) eventually expose the steel to the saline and humid air, causing it to corrode and rust. This not only weakens it but also increases its volume, which causes further cracking of the concrete and degradation of the overall structural integrity. If left unfixed, it could lead to a collapse.
This means two things for engineers. First, regular evaluations—and the implementation of structural recommendations from those evaluations—are vital. Second, structures in critical condition need to be decommissioned, according to the university. Ocean engineers are crucial, Paredes says, as they research how materials are affected by those environments. This includes researching how metals are impacted by water; what chemical reactions take place on the surface of materials exposed to salt water; and how much oxide is released.
“The potential impact directly influences people’s lives and safety,” Paredes says. “It isn’t just advancing research, but it’s results that industry will use in policies, structure construction, and other future applications.”
Currently, Paredes is helping lead a multidisciplinary effort to better understand the corrosion process and to design two distinct corrosion-resistant HEAs in FeAlNiCu-Cr and FeAlNiCu-Ti. Via an international collaboration with the Indian Institute of Technology Madras (Chennai, India), the researchers are aiming to understand how corrosion influences the various mechanisms of deformation at different acidity levels and loading modes.
The materials’ mechanical behavior are being analyzed at Texas A&M, while the materials’ phase formation, stability, and evolution are analyzed—down to near-atomic resolutions—in India.
Source: Texas A&M University, www.tamu.edu.