Booth 346 at ARPA-E Summit 2025

Academic-industry collaborative, supported by the U.S. Department of Energy, developed innovative design strategy that results in prefabricated carbon absorbing building structures:

• High-performance, 3D concrete printed (3DCP), funicular floor structure with minimized mass and maximized surface area for carbon absorption;
• Floor is printed using a novel carbon absorbing concrete mixture;

High-Performing Building Structure

Concrete printed prefabricated funicular floor structure addresses the challenge that embodied carbon accounts for 26-57% of the total life cycle emissions from low energy buildings.

• Proposed floor solution can reduce building life cycle emissions by 60% through:
  1. light and resilient structure requiring less cement and steel reinforcement producing less CO₂;
  2. carbon absorbing concrete formulation;
  3. reduction of construction waste and formwork;
  4. enhanced CO₂ uptake, both in curing and over the building use phase.
• Prefabricated, 3D-printed modular floor structure has 15% less concrete volume, at least 65% more surface area, and 83% less PT reinforcement compared to a conventional post-tensioned (PT) slab (~9″ thick) – incumbent based on using the Post-Tensioning Institute Manual.

Carbon Absorbing Concrete

• The 3D-printable concrete mixture replaces 30% of cement with porous biominerals, reducing CO₂ emissions from raw materials in the mix design, enhancing carbonation activity, and achieving an approximate 70% reduction in total carbon emissions.
• When cured in water, the 2K carbon-absorbing formulation reached 32.4 MPa in 28 days and is projected to reach 40 MPa in 60 days. Its compressive strength is expected to improve further after CO₂ curing. The 2K formulation achieved a 10.7 wt% CO₂ uptake after 24 hours of prehydration and 7 days of CO₂ curing.
• The concrete with porous biominerals demonstrates superior CO₂ sequestration, storing up to 488.7 g of CO₂ per kg of cement—a 142% increase compared to concrete without porous biominerals after seven days of carbonation.

Resilient Prefabricated Structural Design

Comprehensive design and fabrication strategy:

1. Form-finding approach, Polyhedral Graphic Statics, optimizes force flow and identifies post-tensioning placement and force magnitude.
2. Embedded periodic anticlastic surfaces, specifically triply periodic minimal surfaces (TPMS), reduce mass, maximize surface area, and provides structural stiffness and efficient distribution of stress.
3. Integrated void spaces for PT cables ensure precise alignment with constant stress in cables.
4. Geometric materialization generates volume while accounting for 3D-printability and fabrication considerations.

Minimized materials and maximized surface area achieved through 3DCP:

• 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.

Thermal Mass Performance

• item The thermal properties of multiple concrete recipes, including conductivity and specific heat capacity, characterized through Transient Plane Source method tests.
• A comparison of the thermal mass performance between a standard flat and the proposed TPMS slab design was conducted experimentally in climate-controlled chamber. The TPMS floor slab improves indoor temperature damping by 14%, reducing the need of mechanical heating and cooling and therefore reducing the operational carbon emissions.
• Coupled with natural ventilation, the 3D-printed concrete slab design acts as internal thermal mass, dampening the outdoor air temperature fluctuations, and resulting in indoor air and mean radiant temperatures within the thermal comfort zone. This in turn reduces the building heating and cooling energy load.

Life Cycle Assessment

• Proposed 3DCP structural system reduces 67% of GHG emissions compared to an incumbent PT concrete system.
• Emission reductions are due primarily to concrete and steel weight reduction and OPC substitution. Economy of material use also contributes to an estimated 12% operational cost savings over an incumbent PT system, with additional soft-cost and owner-cost savings made possible through shorter construction schedule.

Project Credits

Principal Investigators
Dr. Masoud Akbarzadeh (PI), Associate Professor Architecture, University of Pennsylvania
Dr. Shu Yang (co-PI), Joseph Bordogna Professor Materials Science and Engineering, University of Pennsylvania
Ryan Welch (co-PI), Principal, Research Director KieranTimberlake
Dr. Dorit Aviv (co-PI), Assistant Professor Architecture, University of Pennsylvania
Dr. Zheng O’Neill (co-PI), Professor Mechanical Engineering, Texas A&M University
Dr. Damon Bolhassani (co-PI), Assistant Professor, City College of New York
Dr. Peter Psarras (co-PI), Assistant Professor Chemical and Biomolecular Engineering, University of Pennsylvania