In the recently published ‘Investigations on the foam concrete production techniques suitable for 3D printing with foam concrete,’ authors V. Markin, G. Sahmenko, V.N. Nerella, M. Nather, and V. Mechtcherine explore more about progressive materials for construction. Concrete has been studied in many research labs and by manufacturers around the world as they strive to use construction materials more efficiently with new technologies like 3D printing.
In this research, the authors studied foam concrete created with a mixed foaming method in turbulence, as well as a mixed foaming method created in a cavitation disintegrator. With the addition of 3D printing, industrials users are now able to look forward to better efficiency in production as well as affordability. As the researchers remind us though, 3D printing within the construction industry is still ‘in the early stages.’
Automation is now much more available with robotics, but with that comes new requirements for safety and compliance. Rheological requirements can be challenging too. There are other benefits, however, like a decrease in material weight, better thermal insulation, greater versatility, suitable mechanical properties, and more.
“The primary reason to regard foam concretes as economical and ecological materials is the presence of air cells up to 80% of their total volume,” state the researchers. “The large volume of air cells in foam concrete are often introduced by mechanical aeration of cement mortar using foaming agents.”
For pre-forming, foam and cement paste/mortar are combined to create concrete. With mixed foaming, the foaming agent is added into the matrix mixer, with all ingredients mixed there together. In this study, the team used mixed foaming with the intensive turbulence mixer and disintegrator.
“It is known that intensive mixing improves dispersion of agglomerated cement and micro-filler particles and promotes accelerated hydration processes in foam,” stated the researchers.
Different concepts of feeding system for continues foam concrete printing: (a) Concept 1: manual filling; (b) Concept 2: mixing and pumping; (c) Concept 3: pumping to integrated mixing system; (d) Concept 4: convening and fully integrated mixing system.
Type II Portland composite cement was used, with hard coal fly ash Steament H-4 as a secondary cementitious material.
Chemical composition of cement and fly ash.
Production of foam was successful following the mixed-foaming method using CD- and TM-Mixer. In analyzing the achieved densities, the researchers recognized the benefits of using the cement-based matrix but overall, methods and materials must be investigated further.
“Considering this fact, subsequent addition of the accelerator after foaming of a flowable cement-based matrix need to be explored to meet requirement on the consistency of printable foam concretes presented in [7]. Water absorption measurements revealed the influence of used mixers and corresponding different foaming techniques on microstructure and pore distribution of foam concretes.”
3D printing with concrete is of enormous interest to manufacturers around the world, as well as researchers. From foamed concrete panels to the use of geo-polymer concrete—to reinforcing such materials with 3D printed plastic, many industries can benefit from research and development with concrete.
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Overview of used mixers: (a) cavitation disintegrator (CD): 1. body; 2. conical lid; 3. toothed disks; 4. rectangular recess; 5. impeller; 6. shaft; 7. inlet branch pipe; 8. outlet branch pipe; 9. electric motor; 10. ferrule; 11. plug; 12. leakage opening, and (b) laboratory turbulence mixer (TM): 1. electrical engine; 2. bearing; 3. pressure compensated coupling; 4. vertical shaft.
Mechanical properties of the foam concrete.