3D列印混凝土為一種新型自動化技術，藉由逐層堆疊混凝土達到提升施工效率與降低能源消耗的目的，然而鑑於其在施工過程對材料流變行為之要求，高膠結材料配比設計使其難以達成低碳化發展目的。本研究旨在使用石灰石粉製作3D列印混凝土，以能達到減碳目的。研究針對其新拌、硬固及耐久性質三方面進行測試，探討石灰石粉作為3D列印混凝土材料之適配性以及對工程性質的影響。 本研究區分評估「石灰石粉粒徑對3D列印混凝土流變行為及硬固性質影響」、探討「石灰石含量對3D列印混凝土工程性質影響」及討論「輔助膠結材料應用在石灰石3D列印混凝土對工程性質影響」等三個階段。第一階段，主要評估使用不同粒徑大小(CLP：43.7 μm、OLP：26.9 μm、ULP：4.2 μm、MLP：15.9 μm)非共磨石灰石粉取代水泥以及共磨石灰石水泥(ILPC)，在滿足列印行為要求下，對流變行為及工程性質影響，並根據測試結果篩選適用於3D列印之石灰石粉粒徑；第二階段，探討使用適用於3D列印的石灰石粉粒徑，分別取代水泥(0 %~60 %)和取代粒料(0 %~50 %)應用在3D列印混凝土時，其取代量對3D列印混凝土的工程性質影響，並提出符合可列印性質與工程性質的取代比例及配比建議；第三階段，額外加入不同輔助膠結材料(偏高嶺土(MK)、燃煤飛灰(FA)、水淬爐石粉混摻飛灰，「爐灰」(SA))用以取代水泥，評估輔助膠結材料與石灰石粉複合應用於3D列印混凝土之可行性。 第一階段研究顯示，僅使用粒徑<10 μm之ULP時可滿足3D列印對擠出性質之要求，但用於取代水泥時會產生較高強度折減，較適合用於取代粒料；而ILPC與26.9 μm粒徑大小之OLP在不考慮擠出性質下，具有適中的建造性質及優異之工程性質，均適合用於取代水泥。第二階段研究顯示，以ILPC作為膠結材料條件下，ULP取代粒料體積比例達15 %~30 %時可滿足列印性質要求，在此範圍內隨取代量增加會提升列印性質表現並維持抗硫酸鹽能力，但會降低強度及體積穩定性表現。而以OLP作為膠結材料條件時，OLP取代水泥重量比例在不超過30 %下可維持工程性能要求。第三階段研究顯示，使用MK搭配石灰石粉對混凝土之力學性質表現佳，但增加乾燥收縮量；使用FA搭配石灰石粉時，其混凝土之塑性黏度與力學性質表現較差，但在3D列印不同方向上的強度差異最小，並具有較佳的體積穩定性；使用SA搭配石灰石粉時，可在兼顧力學性能與體積穩定性前提下，提高水泥取代率。在製作工藝上，3D列印試體之抗壓強度較傳統灌漿試體約降低6 % ~ 27 %，但抗彎強度未呈現明顯折減，部分配比甚至更好，顯示本研究所建立之石灰石3D列印混凝土於列印成形後仍維持良好力學性能。綜合不同輔助膠結材料與石灰石粉之複合使用對工程性質之影響，SA在30 %取代水泥並搭配30 % OLP之配比，可滿足本研究對力學行為之最低要求，且能在維持力學性能下改善乾燥收縮狀況並提升減碳效益，展現作為低碳3D列印混凝土膠結材料之應用潛力。;3D concrete printing (3DCP) is an emerging automated construction technology that improves construction efficiency and reduces energy consumption through the layer-by-layer deposition of concrete. However， due to the stringent rheological requirements imposed on printable materials during construction， the high binder content commonly adopted in 3DCP mixtures presents a challenge to achieving low-carbon development. This study aims to develop 3D printable concrete incorporating limestone powder for carbon reduction. The fresh， hardened， and durability properties of the mixtures were investigated to evaluate the suitability of limestone powder for 3DCP and its effects on engineering properties. This study was divided into three stages: evaluating the effects of limestone powder particle size on the rheological behavior and hardened properties of 3DCP; investigating the effects of limestone content on the engineering properties of 3DCP; and examining the effects of supplementary cementitious materials (SCMs) on the engineering properties of limestone-based 3DCP. In the first stage， non-interground limestone powders with different particle sizes (CLP: 43.7 μm， OLP: 26.9 μm， ULP: 4.2 μm， and MLP: 15.9 μm) were used to replace cement， and interground limestone Portland cement (ILPC) was also investigated. Their effects on rheological behavior and engineering properties were evaluated under the requirements for printability， and suitable limestone powder particle sizes for 3DCP were selected based on the test results. In the second stage， limestone powders with particle sizes suitable for 3DCP were used to replace cement (0 %–60 %) and aggregate (0 %–50 %)， respectively. The effects of replacement level on the engineering properties of 3DCP were investigated， and suitable replacement ranges and mixture proportions satisfying both printability and engineering performance requirements were proposed. In the third stage， different SCMs， including metakaolin (MK)， fly ash (FA)， and a blend of ground granulated blast-furnace slag and fly ash， referred to as SA， were additionally used to replace cement to evaluate the feasibility of combining SCMs with limestone powder in 3DCP. The results of the first stage showed that only ULP with a particle size of <10 μm satisfied the extrusion requirements of 3DCP. However， ULP resulted in a greater strength reduction when used as a cement replacement and was therefore more suitable for aggregate replacement. In contrast， ILPC and OLP with a particle size of 26.9 μm exhibited moderate buildability and excellent engineering properties when extrusion performance was not considered， indicating that both were suitable for cement replacement. The results of the second stage showed that， when ILPC was used as the binder， replacing aggregate with ULP at a volume fraction of 15 %–30 % satisfied the printability requirements. Within this range， increasing the replacement level improved printability and maintained sulfate resistance， but reduced strength and volumetric stability. When OLP was used as a cement replacement， the required engineering performance could be maintained at OLP replacement levels of up to 30 % by mass. The results of the third stage showed that the combination of MK and limestone powder provided favorable mechanical properties but increased drying shrinkage. The combination of FA and limestone powder exhibited lower plastic viscosity and mechanical performance， but resulted in the smallest strength differences among different printing directions and better volumetric stability. The combination of SA and limestone powder allowed a higher cement replacement level while maintaining both mechanical performance and volumetric stability. Regarding the manufacturing process， the compressive strength of 3D-printed specimens was approximately 6 %–27 % lower than that of conventionally cast specimens， whereas no evident reduction in flexural strength was observed， and some mixtures even exhibited improved flexural performance. These results demonstrate that the limestone-based 3DCP developed in this study retained favorable mechanical performance after printing. Considering the overall effects of combining different SCMs with limestone powder on engineering properties， the mixture containing 30 % SA as a cement replacement together with 30 % OLP satisfied the minimum mechanical performance requirements established in this study. Furthermore， this mixture improved drying shrinkage behavior and enhanced carbon-reduction benefits while maintaining adequate mechanical performance， demonstrating its potential as a binder system for low-carbon 3D concrete printing.
