LSU Engineering Researchers Seek Advancements in Underwater Construction

A large orange robot arm used for 3D printing concreteNovember 15, 2023

BATON ROUGE, LA – In 2022, the average global sea level reached a record high at 101.2 millimeters—four inches above 1993 levels. That same year, the National Weather Service recorded an all-time high of 13 “significant weather events.” Both of these statistics signal a greater challenge when it comes to the resiliency of coastal communities and their infrastructure, but it’s one a pair of LSU Engineering researchers are taking on through a nearly $500,000 National Science Foundation Future Manufacturing Award.

LSU Civil and Environmental Engineering Assistant Professor Yen-Fang Su and LSU Chemical Engineering Assistant Professor Yaxin An are exploring the potential of additive manufacturing as an autonomous, advanced construction method to overcome the challenges of underwater construction—such as severe working conditions, restricted access, and potential ecological damage. Specifically, the pair will utilize artificial intelligence-driven material modeling to help them select and determine the best bio-based construction materials for use in underwater construction through a novel-sensing approach.

“To successfully implement underwater additive manufacturing, three key aspects must be considered—materials, manufacturing procedures, and instrumentation,” Su said. “Building upon our current work on additive manufacturing and sensing, Dr. An’s team is using molecular dynamics simulations to calculate the important thermodynamic properties in admixture/cement systems that can provide insight for us to select/design the admixtures that have better compatibility between admixture and cement.

“Our team will quantify various properties of the materials using the AI-assisted sensing method developed in our lab, which is supported by an LSU Provost’s Emerging Research Grant, based on the metrics we provided for Dr. An’s group to validate and calibrate the material models. We will further develop a physics-guided, machine-learning model that takes environmental conditions, material composition, and additive-manufacturing process factors into consideration.”

Traditionally, building underwater structural components is complicated and requires pumping or placing concrete using a tremie pipe, a long tube that extends to the seabed and ensures accurate placement while minimizing disturbance to the surrounding water. Repairing those structures once they’re built requires highly-skilled divers equipped with specialized gear and techniques to carry out the process. Neither approach is ideal for various reasons.

“These traditional methods pose numerous challenges in the hazardous conditions which impact both workers and the environment, including harsh working conditions such as low visibility, strong currents, and high pressure,” Su said. “Equipment and technology limitations in underwater environments also present challenges. Although advances in remotely operated vehicles and autonomous underwater vehicles have enabled the inspection and surveying of underwater environments, they have yet to fully address the challenges of underwater construction. Balancing environmental concerns is also crucial for sustainable development in underwater construction. Preserving marine ecosystems and reducing pollution by using biocompatible materials is essential for protecting the environment and ensuring long-term sustainability.”

LSU logo printed in concreteIf their project is successful, both Su and An believe it will not only address those aforementioned challenges, but it will also have far-reaching benefits for the construction industry and coastal communities.

“It will improve our fundamental understanding of the interaction between organic (admixtures) and inorganic materials (cements), providing guidance into the optimization of materials formulation for underwater construction,” An said. “This is the first key step to successfully implementing underwater 3D printing.”

“This will mean we will have sufficient preparation—models, knowledge, technology, workforce—to face future unpredictable challenges in the engineering of future habitats and infrastructure under extreme environments,” Su added. “It will also provide the insight to tackle the extraterrestrial inhospitable environments in the future. The energy sector, defense sector, and underwater robotics will experience innovation from the insights derived from this project.”

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Contact: Joshua Duplechain
Director of Communications