In the quest for sustainable construction materials, researchers have turned to an unlikely ally: rice husks. A recent study led by Jihye Jhun from the Singapore Centre for 3D Printing at Nanyang Technological University has explored the potential of rice husk biochar (RHB) as a partial cement replacement in 3D concrete printing (3DCP). The findings, published in the journal Virtual and Physical Prototyping (which translates to “Virtual and Physical Prototyping”), offer promising insights into enhancing the sustainability of construction practices.
The study investigated the effects of incorporating RHB at varying dosages (2.5–15 vol.%) on the extrudability, buildability, rheology, mechanical strength, and carbon sequestration of 3D-printed concrete. The results revealed a delicate balance between performance and sustainability. “We found that buildability increased with the dosage of RHB and peaked at 10 vol.%, but higher dosages led to failures during initial deposition,” Jhun explained. This suggests that while RHB can enhance certain properties, careful optimization is crucial to avoid compromising structural integrity.
Mechanical strength was another critical factor examined in the study. At 2.5 vol.%, RHB showed a slight improvement in compressive strength compared to the control mix, but higher dosages resulted in a decrease. Flexural strength was more sensitive to microstructural continuity, with higher dosages retaining deficits. “The microstructural analysis indicated a denser interfacial transition zone at lower dosages, but pore discontinuities became apparent at higher levels,” Jhun noted. This highlights the importance of finding the right balance to maintain structural performance while reducing carbon emissions.
One of the most significant findings was the enhanced CO₂ uptake of RHB mixes. All RHB mixes showed higher CO₂ uptake than the control, with a maximum at 5 vol.%. Additionally, incorporating 10 vol.% RHB reduced total CO₂ emissions by 6.7%. “This study advances sustainable 3D-printed materials toward low-carbon and potentially carbon-negative construction,” Jhun stated. The practical operating window identified (2.5–5 vol.%) balances print performance, strength retention, and carbon uptake, offering a viable path forward for sustainable construction.
The implications of this research are far-reaching, particularly for the energy sector. As the demand for sustainable and energy-efficient construction materials grows, the use of RHB in 3DCP could significantly reduce the carbon footprint of buildings. This innovation not only aligns with global efforts to combat climate change but also opens new avenues for waste utilization and circular economy practices.
The study by Jhun and her team represents a significant step towards achieving low-carbon and potentially carbon-negative construction. As the construction industry continues to evolve, the integration of sustainable materials like RHB could play a pivotal role in shaping the future of building practices. The findings published in Virtual and Physical Prototyping provide a solid foundation for further research and development in this exciting field.