Development of sustainable strain-hardening cementitious composites containing diatomite for 3D printing
Fei Teng, Fengming Xu, Minxin Yang, Jie Yu, Dong Zhang, Yiwei Weng
Abstract
3D concrete printing (3DCP) faces challenges in the automated integration of reinforcement. The use of strain-hardening cementitious composites (SHCCs) with high ductility offers a promising solution to this issue. However, the high cement content in printable SHCC increases the carbon footprint, contributing to heavy environmental burden. This study investigates using diatomite (DE), a natural sedimentary rock, to develop sustainable SHCC for 3DCP. Diatomite partially replaces ordinary Portland cement, and the effects of various DE replacement ratios (10 %, 20 %, 30 %) on fresh properties, mechanical properties, hydration, and microstructure are experimentally examined. Sustainability analysis is conducted using life cycle assessment (LCA). Results show that a 30 % DE replacement ratio increases the dynamic yield stress, static yield stress, and plastic viscosity by 31.7 %, 79.7 %, and 239.5 %, respectively. A 10 % DE replacement achieves the highest mechanical properties, with tensile, compressive, and flexural strengths increased by 54.6 %, 14.0 %, and 27.4 %, respectively, compared to the reference group. A 10 % DE replacement ratio enhances the hydration process with increased calcium silicate hydrate gels formation and refines the microstructure. DE replacement ratio above 20 % negatively impacts hydration due to insufficient portlandite, while the porous structure of unhydrated DE increases the total porosity by 18.4 %. LCA results show a 25.8 % reduction in global warming potential can be achieved. The findings reveal that the developed DE-SHCC has the potential to facilitate sustainability and enhance the mechanical properties in construction 3D printing. • Diatomite (DE) is used to develop sustainable SHCC for 3D concrete printing (3DCP). • The fresh properties of the materials satisfies the requirements for 3DCP. • DE replacement ratio of 10 % achieves the highest mechanical performance. • A 10 % DE replacement ratio promotes the hydration and refines the microstructure. • A 30 % DE replacement ratio can reduce global warming potential (GWP) by 28 %.