3D列印纖維永續混凝土材料之開發及減碳效益評估;Development of 3D Printed Fiber Sustainable Concrete Materials and Evaluation of Carbon Reduction Benefits

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题名:	3D列印纖維永續混凝土材料之開發及減碳效益評估;Development of 3D Printed Fiber Sustainable Concrete Materials and Evaluation of Carbon Reduction Benefits
作者:	薛家晨;Xue, Jia-Chen
贡献者:	土木工程學系
关键词:	3D列印工藝;化學摻料;纖維;纖維永續混凝土;減碳效益評估;3D printing technology;Chemical admixtures;fibers;fiber-reinforced sustainable concrete;3D printing technology, Chemical admixtures, Fibers, Fiber-reinforced sustainable concrete, Carbon reduction benefit assessment
日期:	2025-03-31
上传时间:	2025-04-09 15:56:35 (UTC+8)
出版者:	國立中央大學
摘要:	為實現2050年淨零碳排放目標，土木領域需逐步減少碳排放。混凝土3D列印作為高智能化之「綠色工法」，可降低施工過程中之溫室氣體排放。但為滿足材料流變性能要求，目前可列印混凝土在配比設計方面與淨零排放理念相悖。本研究旨在開發適用於3D列印之「3D列印纖維永續混凝土(3DFPC)」，並進行全面的生命週期評估。通過3D列印測試，探討不同永續材料對3D列印混凝土之性能影響，提出適用於3DFPC之推薦配比，並根據生命週期評估結果提供應用建議。研究首先通過對9種永續材料（包括天然礦物、工業及農業副產物）及不同化學摻料對3D列印混凝土基體在新拌及硬固階段之性能測試，可發現矽灰(SF)、燃煤飛灰(FA)和水淬爐石粉(BFS)在高比例取代水泥(PC)時具有較高之應用潛力。同時發現，高性能減水劑D (SPD)搭配複合型黏度改質劑(CVMA)作為最佳之化學摻料組合方案，以維持材料在新拌階段之特性。在進一步對混凝土進行測試時，根據測試結果可發現，在新拌階段，保型率相較於流度值更能有效對混凝土材料之可列印性進行初步評估，建議保型率至少達到87 % 以上以確保材料可具備較高之可列印潛力。在硬固階段，在粒料參數之影響中，機製砂(MS)之性能由於粒形優勢可略優於石英砂(QS)，而砂膠比增加可有效改善材料之乾燥收縮，但提升至1.5對3D列印混凝土之抗壓及抗彎強度均造成明顯之負面影響。膠結材料方面，SF在二元系統中可憑藉粒徑及水化活性優勢而實現較高之強度發展，但過高取代量將導致乾燥收縮明顯提升。而FA及BFS則在高取代量時導致強度削弱，但此現象在三元系統中可得到改善。綜合考慮，採用MS並選擇砂膠比1.25為適用於3D列印混凝土的最佳顆粒設計方案，而膠結材料以二元或三元系統取代50 % 之PC體積可兼顧材料之力學性能與永續性。同時，本研究導入纖維增強技術，測試不同纖維類型（如聚甲醛纖維(POMF)、聚丙烯纖維(PPF)、碳纖維(CF)、玄武岩纖維(BF)及硫酸鈣晶鬚(CSW)）之適用性，分析纖維長度及用量對材料可列印性及硬固階段性質之影響。結果可發現，除BF在新拌階段存在堵塞噴頭橫向而不適用於3D列印工藝外，POMF與PPF隨添加量增加可明顯提升混凝土韌性，但會導致強度降低；CF及CSW隨添加量增加可提升強度，但對韌性則沒有貢獻。通過多種纖維之性能對比與協同優化，確定以0.5 % 之PPF使材料在韌性方面有所提升，並同時搭配1.0 % 之CSW，實現高強度與韌性之結合。綜上述所，在3DFPC配比設計中，建議採用MS以砂膠比1.25進行粒料設計，而在膠結材料則採用三元系統，以SF搭配FA以取代50 % 之PC體積，並以上述之複合纖維設計方案進行纖維增強，以此同時兼顧工程性質及減碳效益。本研究所提出之3DFPC建議配比之抗壓及抗彎強度分別可高達88.9及13.6 MPa，韌性在3D列印之Y軸方向最高可達6,174 J，在強度表現方面可具備明顯優勢，其抗壓及抗彎強度相較於其他研究中所使用之混凝土材料而言可達約50.4 % 及38.1 % 之平均強度提升。同時發現，3D列印工藝所導致之強度損失主要源於結構體內大孔隙之數量增加，此外，列印設備之局限性及列印層尺寸變化等因素皆可能削弱其力學性質。而此工藝所造成之力學各向異性則主要受不同方向上之層間界面數量及形式差異影響，在抗壓強度方面，荷載方向平行於列印方向時之強度可高於垂直方向，但在抗彎強度方面則情況相反。此外，纖維之特殊排列將加劇抗彎強度之各向異性特性。至於壓彎比，荷載平行於列印方向之表現在3DPC中高於垂直方向，而在3DFPC中則沒有明顯差異。在環境效益方面，研究通過碳排放量化分析與生命週期評估，全面探討3DFPC在原材料使用及結構建造過程中之環境影響。基於碳係數法之計算結果表明，與傳統3D列印混凝土配比相比，所提出之3DFPC建議配比設計可在原材料層面平均減少約40 % 之碳排放。同時，在建造相同功能構件時，以此材料搭配3D列印工藝使用可較傳統灌漿減少約6.6 % 之碳排放。此外，生命週期評估結果顯示，在系統邊界設定為「從搖籃到現場」之前提下，在3D列印工藝中採用本研究之建議3DFPC配比設計分別可在建案材料生產、運輸及施工階段較傳統灌漿工藝實現約22 %、41 % 及11 % 之碳排放減量，整體可達之減排效益約為26 %，且若基於此材料之性能而進行結構優化設計可具有進一步減少碳排之潛力。綜上所述，本研究提出之3DFPC可同時兼顧力學性能與環境效益，為3D列印技術在土木工程領域之推廣提供理論支持，為實現2050年淨零碳排目標提供有效方案。 ;To achieve the 2050 net-zero carbon emission target, the civil engineering sector must gradually reduce its carbon emissions. As a highly intelligent "green construction method," 3D-printed concrete can reduce greenhouse gas emissions during the construction process. However, to meet rheological performance requirements, current printable concrete mix designs often conflict with net-zero emission principles. This study aims to develop "fiber-reinforced 3D-printed sustainable concrete (3DFPC)" tailored for 3D printing and to conduct a comprehensive life cycle assessment (LCA). Through 3D printing tests, the effects of various sustainable materials on the performance of 3D-printed concrete are explored, a recommended mix design for 3DFPC is proposed, and application recommendations are provided based on the LCA results. The study first evaluates the fresh and hardened properties of 3D-printed concrete matrices using nine sustainable materials (including natural minerals, industrial by-products, and agricultural residues) and various chemical admixtures. It is found that silica fume (SF), fly ash (FA), and ground granulated blast furnace slag (BFS) exhibit significant potential when used to replace a high proportion of Portland cement (PC). Additionally, superplasticizer D (SPD) combined with a composite viscosity-modifying admixture (CVMA) is identified as the optimal chemical admixture combination for maintaining fresh properties. Further testing reveals that during the fresh state, shape retention is more effective than flowability in assessing the printability of concrete materials. A minimum shape retention of 87% is recommended to ensure high printability potential. In the hardening stage, among the influences of aggregate parameters, the performance of manufactured sand (MS) can be slightly better than quartz sand (QS) due to its particle shape advantage. An increase in the sand-to-binder ratio can effectively improve the drying shrinkage of the material, but raising it to 1.5 has a significant negative impact on both the compressive and flexural strength of 3D-printed concrete. Among binders, SF achieves higher strength development in binary systems due to its particle size and pozzolanic activity but leads to significant drying shrinkage at high replacement levels. FA and BFS result in strength reduction at high replacement levels, which is mitigated in ternary systems. Overall, using MS with an A/B ratio of 1.25 and replacing 50% of PC volume with a binary or ternary binder system balances mechanical performance and sustainability. The study also introduces fiber reinforcement techniques to test the applicability of various fibers (e.g., polyoxymethylene fibers (POMF), polypropylene fibers (PPF), carbon fibers (CF), basalt fibers (BF), and calcium sulfate whiskers (CSW)). The impact of fiber length and dosage on printability and hardened properties is analyzed. Results indicate that BF causes nozzle blockage in the fresh state and is unsuitable for 3D printing. POMF and PPF enhance toughness with increased dosage but reduce strength. Conversely, CF and CSW improve strength but do not enhance toughness. Through optimization, a combination of 0.5% PPF for toughness improvement and 1.0% CSW for strength enhancement is identified, achieving a balance of high strength and toughness. Based on these findings, the recommended mix design for 3DFPC includes MS with an A/B ratio of 1.25 for aggregate design, a ternary binder system with SF and FA replacing 50% of PC volume, and the aforementioned composite fiber reinforcement strategy. This design achieves compressive and flexural strengths of up to 88.9 MPa and 13.6 MPa, respectively, with a toughness modulus in the Y-axis direction of 6,174 J for 3D printing. Compared to other 3D-printed concrete materials, the compressive and flexural strengths show average improvements of approximately 50.4% and 38.1%, respectively. Strength loss in 3D-printed structures is attributed primarily to increased macroporosity, as well as limitations of printing equipment and layer size variations. The anisotropy of mechanical properties is influenced by the number and type of interlayer interfaces, with compressive strength higher in the loading direction parallel to the printing direction, while flexural strength is higher in the perpendicular direction. The unique fiber alignment exacerbates flexural strength anisotropy. Regarding the compression-to-bending ratio, 3DPC shows higher performance in the parallel loading direction, whereas no significant difference is observed in 3DFPC. From an environmental perspective, the study employs carbon emission quantification and LCA to examine the environmental impact of 3DFPC in raw material usage and construction processes. Results calculated using the carbon coefficient method indicate that the proposed 3DFPC mix design reduces raw material carbon emissions by approximately 40% compared to conventional 3D-printed concrete. For constructing equivalent functional components, this material combined with 3D printing reduces carbon emissions by approximately 6.6% compared to traditional casting methods. LCA results show that adopting the proposed 3DFPC mix design in 3D printing achieves carbon emission reductions of approximately 22%, 41%, and 11% during material production, transportation, and construction stages, respectively, compared to traditional casting methods. The overall reduction in emissions is about 26%, with further potential for optimization through structural design. In conclusion, the proposed 3DFPC integrates mechanical performance and environmental benefits, providing theoretical support for promoting 3D printing technology in civil engineering and offering an effective solution for achieving the 2050 net-zero carbon emission target.
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