Logistics and Manufacturing Under Attack: Future Pathways Proceedings of a Workshop (2022) / Chapter Skim
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2 Additive Manufacturing of Large Structures
2 Additive Manufacturing of Large Structures
Pages 5-21
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From page 5... ...
The potential to use indigenous or waste materials, for example, could enable rapid, adaptive construction of large structures in remote locations, which has important implications for supply logistics as well as for failure prediction, testing, and qualification. To explore opportunities and challenges in this space, workshop participants examined recent advances in large-scale 3D printing, alternative methods for producing cement, and other cutting-edge construction materials and techniques.
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From page 6... ...
COBOD began with a grant from the Danish government to conduct a 3-year study of state-of-the-art global construction methods. Observing that the industry was ripe for improvement and innovation, the organization refined the technology to dramatically reduce printing time -- from weeks to days -- and d evelop e quipment that does not require highly specialized expertise to deploy.
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From page 7... ...
SkyBAAM: PORTABLE INFRASTRUCTURE-SCALE 3D PRINTING Brian Post, ORNL ORNL developed SkyBAAM in an effort to modernize the construction industry and replace wasteful, dangerous, and heavily mechanized practices with largescale concrete additive manufacturing (AM) solutions.
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From page 8... ...
As to whether a digital twin could be recorded for inspection, Post answered that this approach works well with metal printing, but said that it will require additional work to develop accurate models and gain the trust of standards com mittees for using digital twins in concrete construction. One challenge with model validation, for example, is that if the concrete cures too quickly, structural integrity could be affected.
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From page 9... ...
Marks underscored the need to digitize all aspects of a company's product workflow to create a platform of automated, interconnected, and optimized processes. Marks outlined several essential elements for enabling industrialized construction: building information modeling; data for manufacturing and assembly; generative design tools; and data informed assemblies that enable robotics, automation, and other advanced building and manufacturing methodologies.
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From page 10... ...
Following their remarks, Kurfess moderated an open discussion. REMOTE 3D PRINTING AND DEPLOYMENT Peter Stynoski, ERDC Stynoski is the materials subject matter expert on the ERDC Additive Con struction team, whose goal is to build capability to print customized structures in a forward environment on demand, with locally available materials and minimal loss of life.
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From page 11... ...
A better understanding of how material changes on a microstructural level affect material performance, which in turn affects structural performance, can be used to create tools to simulate or predict 3D-printed materials' structural performance. In addition, Jones noted that combining data from multiple tests such as electrical conductivity and other tests that are nondestructive can help to eliminate the need for destructive testing.
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From page 12... ...
Other advantages include lower labor needs, shorter construction time, lower transportation costs, and safer practices.2 There are also challenges. Key barriers include the cost of the printers; the availability of printing materials; a limited skilled workforce; and a lack of univer sal standards, structural codes, and finishing requirements.
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From page 13... ...
Morán-del Pozo, 2021, Mechanical and microstructural properties of recycled concretes mixed with ceramic recycled cement and secondary recycled aggregates: A viable option for future concrete, Construction and Building Materials 270:121455, https://doi. org/10.1016/j.conbuildmat.2020.121455.
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From page 14... ...
Stynoski added that new clauses in the Unified Facilities Criteria and Unified Facilities Guide Specifications, compatible with existing codes, could help printed structures meet performance-based criteria, but stressed that inspectors and professional engi neers will need the right data to validate a structure properly. Jones added that it is crucial to understand how in situ measurements relate to material properties, processing procedures, and the resulting structural performance that is being
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From page 15... ...
A typical ERDC workflow starts with site reconnaissance, sampling local materials, and slowly enlarging trials until the right mix of both buildable and pumpable concrete is identified for onsite mixing and printing. The goal, where service members run projects themselves via low logistics within the local economy, is close to reality, he said, but requires more industry-academic efforts.
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From page 16... ...
BioLITH tile is created from a single microorganism that is cultured to build a biofilm that is then combined with nutrients and a sand-based aggregate to create a solid block. These blocks are manufactured using equipment and facilities simi lar to those used in traditional concrete production, and the tiles are installed via standard construction methods.
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From page 17... ...
In another DARPA project, BioMASON is creating lighter-weight concrete landing strips out of local materials in forward-operating bases where soil conditions and dust impact landing ability. While it currently requires scientific expertise to implement this process in the field, Dosier said that the company is working toward a streamlined process that would allow military personnel to build the landing strips with available military hardware and without specialized expertise.
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From page 18... ...
Using industrial by-products or recycled materials, such as fly ash or silica fume, in Portland cement is already standard worldwide practice. However, this practice is harder in remote areas because of the higher level of grinding and blending required, which makes quality control difficult.
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From page 19... ...
Unfortunately, there could be availability constraints to some clinker substitutes, such as fly ash, and Hun said that more alternatives are needed.12 Worldwide approaches to reduce carbon in concrete include using alternative binders, adding CO2 during concrete mixing, using CO2 in concrete curing, and sequestering CO2 while producing aggregate. Combining these approaches could attain carbon-negative concrete, Hun said.
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From page 20... ...
In addition, Tomonori Saito, also a collaborator, said that the team was researching which polymer binder was the most promising to be readily adopted by the concrete industry. GENERAL DISCUSSION In the day's final discussion session, attendees covered issues related to sustain ability, lifespan, workforce, and scaling up for novel concrete alternatives in 3D printing and beyond.
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From page 21... ...
John Koszewnik, Achates Power, reflected that all of the projects hold tremendous opportunity for many commercial and military applications. Not only do these novel approaches to concrete production and use bring benefits in terms of emissions reductions and sustainability, but they also bring improvements in terms of mechanical properties.
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