3D列印技術已廣泛應用於建築與土木工程領域，所需列印材料除仍兼顧工程性能，亦逐漸朝向資源再利用與永續發展邁進。本研究主要欲提高廢棄砂砱之去化比例，探討其應用於鹼激發爐石作為3D列印材料可行性。配比設計中採用不同爐石與砂砱比例介於 1：2.25 至 1：2.75之範圍，搭配不同粗細砂砱混合比例，探討對其所製成材料於3D列印製程下可列印性、抗壓強度、抗彎強度、長度變化率，以及沿不同列印方向所造成之非均向性等影響。
3D列印實作結果顯示，此配比範圍內，所有配比設計皆可維持穩定擠出與成形表現，亦即皆具可列印性。同時，各配比設計之列印材料試體28天齡期抗壓強度可達30至56 MPa，28天抗彎強度則介於4.2至11.3 MPa之範圍。此外，3D列印材料不同主軸方向之力學性質存在非均向性特質，其中，以沿列印之X方向最佳，條間Y與層間Z兩方向次之，且條間與層間數據無顯著差異，而抗彎強度之非均向性較抗壓強度更加明顯。最後，各配比設計試體於7天齡期呈現微幅收縮或膨脹行為，隨齡期增加所有配比皆逐漸轉換為收縮行為，至28天齡期時之變化率達-0.121至-0.586 %之間。綜合上述各試驗結果顯示，砂砱應用於製作鹼激發3D列印材料，確具可行性與開發潛力。

With the rapid development of three-dimensional printing in the fields of architecture and civil engineering, increasing attention has been paid not only to engineering performance but also to the resource reutilization and sustainability of printable materials. This study investigates the feasibility of reusing waste coral gravel as aggregate in alkali-activated slag–based materials for 3D printing, with the objective of increasing the utilization of discarded coral gravel. Mixture proportions were designed with slag-to-coral gravel ratios ranging from 1:2.25 to 1:2.75, combined with varying proportions of coarse and fine coral gravel. The printability, mechanical properties, dimensional stability, and printing-induced anisotropy of the materials were systematically evaluated.
The experimental results demonstrate that all mixtures within the investigated range achieved stable extrusion and maintained adequate buildability during the 3D printing process, indicating satisfactory printability. At 28 days, the compressive strength of the printed specimens ranged from 30 to 56 MPa, while the bending strength ranged from 4.2 to 11.3 MPa. Mechanical properties exhibited clear anisotropic behavior depending on the printing direction. Specimens loaded along the printing direction (X-direction) showed the highest strength, whereas those tested along the inter-filament (Y-direction) and inter-layer (Z-direction) directions exhibited relatively lower but comparable performance. The anisotropy was more pronounced in bending strength than in compressive strength. In terms of dimensional stability, slight expansion or shrinkage was observed at early ages, followed by gradual shrinkage with increasing curing time. The length change at 28 days ranged between −0.121% and −0.586%.
Based on the overall results, the reuse of waste coral gravel in alkali-activated 3D printing materials is technically feasible and shows promising potential for sustainable construction applications.

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