This technology introduces the first method for 3D printing concrete that both captures and stores carbon while forming self-supporting structures. By replacing part of the cement with natural biominerals and using triply periodic minimal surface (TPMS) designs, the process achieves high CO₂ absorption, strong mechanical performance, and significant material savings. The result is a scalable, sustainable alternative to conventional concrete that addresses one of the largest sources of global greenhouse gas emissions without compromising strength or durability.

Longer Description:

Concrete, the world’s second most utilized material (~30 Gt annually) after water, accounts for 8% of global greenhouse gas emissions. Therefore, replacing conventional concrete with carbon-capturing and storage (CCS) alternatives could sequester carbon at the billion-tonne scale, positioning the built environment as a viable contributor to global decarbonization efforts. However, the current state of CCS concrete remains limited by inefficient carbonation kinetics, high energy requirements, and material constraints. A widely adopted approach to mitigating CO2 emissions is to partially replace cement with supplementary cementitious materials (SCMs) such as fly ash, silica fume, and alkaline earth minerals. However, the degree of carbonation is typically limited to the surface layers, leading to inhomogeneous mechanical properties. Porous materials have been widely explored to increase CO2 uptake. However, excessive porosity compromises mechanical strength, undermining the core function of concrete as a durable construction material. Further, many porous materials are not scalable or cost-effective for construction purposes.

3D concrete printing offers a transformative pathway by enabling precise geometric control, eliminating the need for formwork, and significantly reducing construction waste. However, concrete has a density twice that of plastics, making it difficult to print concrete of complex structures that have large curvatures. Traditionally, concrete mixtures have no shapes before drying; their manufacturing relies on cast-in-place using a removable framework. Therefore, control of the rheology of the concrete ink, where water is needed, vs. the differential drying from the bottom layer to the top, and even CO2 absorption across the prints inside out, has been very challenging. As a niche manufacturing process, concrete 3D printing has been limited to the use of conventional concrete materials. No group has reported 3D printing of CCS concrete let alone reporting 3D printing of them in complex structures such as the self-supporting, triply periodic minimum surface (TPMS).

TPMS structures, as manifested in sea stars, plants, and human bones, have emerged as promising architectures that offer heightened structural stability, maximal surface areas, and superior energy absorption. Working with Masoud Akbarzadeh’s group at Penn Design, the Yang lab at Penn Engineering reported the first example of 3D printed CCS concrete in self-supporting diamond TPMS structures with 78% reduction in material usage. Through design optimization of the print geometry and the intelligent choice of porous materials, we show high print fidelity (more than 100 layer), high CO2 capturing efficiency, and high mechanical strength. Specifically, we replace cement with 30 wt% highly accessible biominerals, diatomaceous earth (DE), achieving a maximum absorption of 488.7 gCO2 kgcement-1 in 7 days, approaching the theoretical CO2 uptake maximum and a 142% increase over conventional concrete, without scarifying the compressive strength of the concrete. The TPMS geometry offers 30% higher CO2 uptake rate vs. a concrete cube, and the carbonation is found evenly distributed across the print depth.

The reported 3D printing of CCS concrete offers a pathway toward scalable and sustainable solutions to a real-world problem without undermining concrete’s structural functions. The insights from our work will inspire the creation of new materials, new designs, and new concrete manufacturing methods that are not possible today.

Read more in this article in Advanced Functional Materials

The Yang lab is interested in developing novel materials synthesis, assembly and eco-manufacturing of complex, multi-functional, nano- to macrostructured soft, sustainable materials and composites. By coupling chemistry, fabrication, and external stimuli, the Yang lab addresses the fundamental questions at the surface-interface in precisely controlled and sometimes extreme environments, and studies environmental responsiveness and the related structure-property relationship. Special interests involve novel design, synthesis and engineering of well-defined polymers, gels, colloidal particles, liquid crystals, and composites with controlled size, shape, and morphology over multiple length scales, and investigate dynamic responses, mechanical instabilities, and structural evolution in soft and geometric substrates. By directed patterning and assembly of nano- and micro-objects in solutions and on patterned surfaces, they explore unique surface, optical, and mechanical properties and their dynamic tuning for relevant and societally impactful applications, including coatings, dry and wet and reversible adhesives, smart windows, displays, (bio)sensors, soft robotics, biomedical devices, wearables, dehumidifiers, and carbon capture and storage concrete for a better and more sustainable future.