Abstract
This work examines the development of an environmentally friendly one-part geopolymer concrete suitable for extrusion-based 3D printing. A total of 27 mixtures were analyzed by systematically varying precursor blends (ground granulated blast-furnace slag (GGBS) and fly ash), aggregate-to-binder ratios, and powdered activator contents. A qualitative "bucket test" was evaluated as a potentially site-friendly consistency-screening technique and showed good agreement with flow-table observations. Within the investigated material and printing conditions, a candidate printability window was associated with zero slump and a slump-flow diameter of 140–180 mm. To balance pumpability with structural build-up, the reduction in slump flow after a 10 min rest period was typically 10–15 mm for the Type-II candidate mixtures. Among the six Type-II candidates, CM-12 (50% GGBS, aggregate-to-binder ratio 1.5, and 10% activator) showed the best overall extrusion and shape-retention response and was used to print a continuous 12-layer object. Printing reduced density by 3.48–8.01% relative to mold casting, while the printed specimens showed a direction-dependent compressive response; no claim of statistically significant anisotropy is made from the available replicate set. The mold-cast mixtures developed 28-day compressive strengths of 32.7–41.29 MPa. The findings support the bucket test as a rapid preliminary screening method rather than a stand-alone predictor of successful printing. Further validation across materials, environmental conditions, and printer configurations is required before the numerical limits can be used as general site-control criteria.
Keywords
Geopolymer Concrete, 3D Printing, Printability, Mix Consistency, Flow Assessment, Compressive Strength,Downloads
References
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