3D-Printed Carbon Absorbing High-Performance Building Structure
Authors
Dr. Masoud Akbarzadeh (PI), Assistant Professor, Architecture, University of Pennsylvania
Dr. Dorit Aviv (co-PI), Assistant Professor, Architecture, University of Pennsylvania
Dr. Damon Bolhassani (co-PI), Assistant Professor, Architecture, The City College of New York
Billie Faircloth, Adjunct Professor, Architecture, University of Pennsylvania
Dr. Zheng O’Neil (co-PI), Associate Professor, Mechanical Engineering, Texas A&M University
Dr. Peter Psarras (co-PI), Assistant Professor, Chemical and Biomolecular Engineering, University of Pennsylvania
Ryan Welch (co-PI), Principal and Research Director, KieranTimberlake
Dr. Shu Yang (co-PI), Joseph Bordogna Professor, Materials Science and Engineering, University of Pennsylvania
Polyhedral Structures Laboratory, Architecture, University of Pennsylvania: Dr. Maximilian E. Ororbia (Postdoctoral Fellow), Hua Chai, Yefan Zhi, Teng Teng (PhD Student), Pouria Vakhshouri (Design Researcher)
Shu Yang Group, Materials Science and Engineering, University of Pennsylvania: Dr. Kun-Hao Yu (Postdoctoral Fellow), Sohee Nah (PhD student)
Thermal Architecture Lab, Architecture, University of Pennsylvania: Dr. Xiang (Jason) Zhang (Postdoctoral Fellow), Zherui Wang (Ph.D. student)
Advanced Building Construction Lab, Architecture, City College of New York: Dr. Fahimeh Yavartanoo (Postdoctoral Fellow), Javier Tapia (Undergraduate researcher)
Building Energy and HVAC&R Research Group, Mechanical Engineering, Texas A&M University: Youngsik Choi (PhD student)
Project Date
2022-
Acknowledgements
This research is funded by the Advanced Research Projects Agency – Energy (ARPA-E) of U.S. Department of Energy (DE-FOA-0002625 2625-1538).
Technology Summary
Innovative carbon-absorbing building structure
- High-performance, prefabricated funicular floor structural system with minimized mass and reinforcement, as well as maximized surface area for enhanced carbonation.
- Novel carbon-absorbing concrete mixture.
- Reduced construction materials and waste and enhanced structural performance using prefabricated modular system with concrete 3D-printing and post-tensioning technologies.
- Reduced operational energy over building’s life cycle by exploiting thermal mass and optimizing heat pumps for electrified building systems.
The combined strategies ensure significant greenhouse gas emission reduction on a cradle-to-gate and cradle-to-grave basis.
Efficient Structural Design
Post-tensioned funicular floor structure.
- Prefabricated, 3D-printed modular floor structure with minimized concrete mass, ~60% less compared to conventional reinforced slabs, and maximized surface area for carbonation.
- Funicular beams with embedded periodic anticlastic surfaces framing a compression only arch in a post-tensioned (PT) dual-banded scheme reduces amount of concrete and PT reinforcement, ~15% and ~80% less than conventional PT floors, respectively, and increases overall floor system efficiency.
- Comprehensive design and fabrication strategy:
- Form-finding approach, Polyhedral Graphic Statics, optimizes force flow and identifies post-tensioning placement and force magnitude.
- Embedded periodic anticlastic surfaces reduce mass, maximize surface area, and provide geometric stiffness.
- Integrated void spaces for PT cables ensure precise alignment with constant stress in cables.
- Geometric materialization generates volume while accounting for 3D-printability and fabrication considerations.
Carbon-Absorbing Concrete
Strong and printable carbon capture mixture.
- Concrete mixture replaces 30% cement with naturally abundant silica biominerals with hierarchical pores, reducing CO2 emissions and enhancing carbon sequestration efficiency; resulting in ~60% less net carbon emissions per kg of concrete.
- 3D-printable and lightweight concrete mixture, achieving a compressive strength of ~ 40 MPa and a tensile strength of ~3 MPa, ideal for printing complex geometries.
- Concrete mixture achieves a carbon absorption efficiency of 489 g CO2/kg of cement, 142% higher than conventional concrete.
- 3D-printed cube with embedded triply periodic minimal surfaces (TPMS) has a 175% greater CO2 uptake rate efficiency than a cube made from a standard concrete mix, demonstrating effectiveness of both the carbon absorbing concrete mixture and the increased geometric surface area-to-volume ratio.
- Developed a material design strategy to print the floor structure prototype using a commercial 2K robotic printing system.
3D-Printed Prefabrication
Minimized materials and maximized surface area.
- Combined use of 3D-printing and post-tensioning technologies reduces amount of construction materials required and waste produced.
- Developed concrete 3D-printing algorithms capable of slicing complex geometries, identifying overhang locations, and generating printing toolpaths with minimal start and stops, overall optimizing designs to be self-supporting and ensuring quality.
- Efficient and effective assembly, construction, and post-tensioning protocols.
Experimental and Numerical Testing
Test and model structural and material performance.
- Flexural test performed on prototype informed failure mode, ultimate load-bearing capacity, construction and post-tensioning protocal improvements, and overall design enhancement.
- Calibrated finite element (FE) model developed for post-tensioned, modular structural system, calibrated with different printable concrete mixtures.
- Material testing prototocals developed to evaluate strength of 3D-printed samples, different carbon-absorbing mix and calibrate FE model.
- Experimental tests and calibrated numerical model further inform design strategy of the floor system.
Thermal Mass Performance
Thermal efficiency gains and energy savings.
- Coupled with natural ventilation, structural floor design acts as internal thermal mass, dampening outdoor air temperature fluctuations, resulting in indoor air and radiant temperatures within comfort zone; in turn, reducing building’s heating and cooling energy load.
- Expanded surface area of TPMS geometry in comparison with a flat slab, can increase the heat transfer rate between the air and the mass, without increasing the embodied carbon of the structure.
- The proposed HVAC system, including a ground-source heat pump and radiant system, along with TPMS structure can reduce aggregated carbon emissions by ~40% to 70% from 2030 to 2090 in regions near New York City area.
- Possible to achieve carbon-free building HVAC operation by adopting proposed system, before 2060 in some regions, underscoring importance of electrifying building HVAC systems to reduce carbon emissions.
- The optimal control of radiant water temperature can reduce ~19-37% energy savings by taking advantage of TPMS structure’s larger thermal mass, compared to typical rule-based controls (RBC).
Life Cycle Assessment
Life cycle stage assessment of structural system.
- Flow of materials, energy, and labor costs for manufacturing and installation processes of incumbent and proposed structural systems determined using an integrated LCA.
- Preliminary TEA analysis points to cost savings over incumbent systems on materials, energy, and labor for manufacturing and installation from 25% to 35%, before taking into account carbon incentives.
- Comparative LCA screening studies show that the proposed system will likely achieve between 70% and 80% upfront- and lifecycle- GWP reductions over the incumbent system.
- Additional savings are likely to be identified in end-of-life scenario modeling of modular system recovery, recycling, and reuse.
- Hotspot analysis reveals concrete mix ingredients as the largest contributor to GWP, although benchtop tests of CO2 absorption suggest much of this can be offset upfront.
- Steel sourcing identified as the second most signficant factor for upfront GWP.
- Electricity consumption for concrete extruding, assembly, and tensioning have also been identified as key contributors to GWP, suggesting further opportunities for optimization through electricity procurement and scale-up efficiency.
Tech-to-Market
Structural system prefabrication and construction.
- Prefabrication using concrete 3D-printing.
- Dual-banded post-tensioned funicular beam framing.
- Compression only, ribbed floor arch.
