Exploring Low-Carbon Cementitious Materials for 3D Printing Applications : A Comparison Between Limestone Calcined Clay Cement (LC3) And One-Part Alkai-Activated Material (AAM)

The utilisation of low-carbon cement containing construction and dem-olition waste (CDW) in 3D printing has received significant attention as a suitable approach to conserve natural resources and reduce the carbon footprint of con-struction materials. This study introduces and compares the printability of two low-carbon systems, namely limestone calcined clay cement (LC3) and one-part alkali-activated materials (AAMs), containing excavated clay waste and end-of-life brick powder as binder materials, respectively. The developed systems’ flow-ability, open time, mechanical strength, shape retention and buildability were in-vestigated. The flowability of the mixtures was comparable and adequate for a smooth extrudability. The open time of the LC3 system was around four times higher than the one-part AAM. The study showed that one-part AAM has superior mechanical strength after 3 days, much higher than that of LC3 after 28 days. Both investigated systems of mix formulations had acceptable buildability, i.e., without rapture and tilting of the upper layers. Overall, the results present a promising application for using low-carbon cementitious materials as a feedstock for 3D printing applications. The culminated results suggest that LC3 formulation using excavated clay is best suited for medium to large-scale and one-part AAM using end-of-life brick for small to medium-scale objects. The outcome of this study can be crucial in decreasing the overdependence on limited resources and allowing construction automation.