Preliminary Investigation Into the Development of Cement-Free Composites Using Emerging Alternatives for 3d Printing

Cement production triggers adverse environmental issues primarily characterized by high carbon dioxide (CO2) emissions and resource depletion. While ample research has been conducted on cement-free binders for different applications in construction, very few studies considered developing such binders without complex activation techniques for 3D printing. This study aims to develop cement-free composites made of volcanic ash (VA) and calcium carbide residue (CCR) activated by only 1% NaOH for 3D printing applications. Different binder-to-aggregate (b/a) ratios and superplasticizer (SP) contents were considered. Additionally, natural fine aggregates (NFA) were partially replaced with desert dune sand (DDS) to promote sustainable practices further. The composites were tested for flow and compressive strength at 3 and 7 days. The experimental evaluation showed that performance applicable for 3D printing was obtained for mixes made with a b/a ratio of 1-1.5, SP content of 1% by binder mass, and DDS substitution rate by NFA of 25-50% by mass. The developed composites exhibited a 145-160 mm flow and compressive strength of 16.6-17.7 and 21.7-22.1 MPa at 3 and 7 days, respectively. The study offers a promising foundation for developing innovative cement-free composites using emerging alternative materials while avoiding costly and energy-intensive activation methods.