| 摘要: | 3D列印混凝土技術是一種自動化建築技術，相較於傳統灌漿工法在建築過程可達到更高的幾何自由度及更低的材料消耗。本研究使用多種類型的永續材料並以高比例取代傳統材料、添加纖維改善性能，製作具永續性的3D列印纖維增強混凝土，對其進行新拌性質、硬固性質與乾燥收縮三方面的測試，探討永續材料與纖維應用於3D列印混凝土之適配性以及對工程性質的影響。
本研究分為「永續膠結材料對水泥漿體工程性質之影響」、「永續材料對3D列印混凝土工程性質之影響」及「纖維對3D列印混凝土工程性質之影響」三階段進行探討。第一階段旨在探討不同永續膠結材料（壓密矽灰(SFD)、未壓密矽灰(SFU)、飛灰(FA)、爐石粉(BF)、石灰石粉(LS)、偏高嶺土(MK)、紙漿污泥飛灰(PSFA)、超微細飛灰(RUFA)、牡蠣殼粉(OSP)及硫酸鈣晶鬚(CSW)）在新拌階段時靜置不同時長（0 min、10min及30 min）對水泥漿體的新拌性質及工程性質之影響；第二階段在研究較具潛力之永續膠結材料以不同比例（30 %、40 %、50 % 及60 %）取代水泥，以及使用永續粒料（機製砂(MS)及人工砂(AS)）應用於3D列印混凝土，對新拌性質、3D列印之可列印性、硬固性質及乾燥收縮的影響，並提出符合工程性質與永續效益之配比；第三階段使用纖維（聚甲醛纖維(POMF)、聚丙烯纖維(PPF)、碳纖維(CF)、CSW）添加於3D列印混凝土中，探討單一纖維對工程性質之影響，並根據不同纖維的特性設計複合纖維配比，探討複合纖維改善3D列印混凝土之效果與適配性。
第一階段研究結果顯示，使用SFD、SFU、FA、BF、MK及RUFA取代水泥(PC) 30 % 製作3D列印混凝土，不影響可列印性並具有足夠的水化能力保持混凝土強度。第二階段研究結果顯示，使用較具潛力之永續膠結材料（SFD、FA及BF）與永續粒料製作3D列印混凝土，在添加適量藥劑後皆可符合可列印性標準，唯流度值會因材料而有所不同，保型率則在85 % 以上。永續膠結材料取代PC時，考慮配比的永續性與強度，最佳取代比例為50 %，過多會造成強度下降，過少則永續性不足；乾燥收縮方面，不同永續膠結材料在適當的PC取代比例下皆可減少試體的收縮量，其中FA的效果最佳，其次為BF，SFD若添加過量 (≤ 60 %)則會使收縮量增加。永續粒料中，AS有良好的保型率，但強度過低且有嚴重的體積穩定性問題，MS在保型率與強度皆表現良好，較適合應用於3D列印混凝土中。第三階段研究結果顯示，不同纖維在力學性能方面，POMF與PPF可提升混凝土的韌性，但會使強度降低，CF與CSW可提升強度，但對韌性較無幫助；在乾燥收縮方面，適量添加POMF(≤ 1.5 % )與CF(≤ 1.0 %)可減緩收縮速率，PPF與CSW則會使收縮量隨添加量的增加而增長。整體研究結果顯示，3D列印工藝會使混凝土強度較傳統灌漿低並造成各向異性，抗壓強度方面無添加纖維時各向異性為X向 > Z向 > Y向，添加纖維時為X向 > Z向 ≒ Y向，抗彎強度方面各向異性皆為Y向 > X向，但整體變異係數皆接近0，表示不同方向上的強度差距不大。根據試驗結果提出可用於3D列印工藝的纖維增強混凝土配比設計，SFD與FA以1：1比例取代PC體積比共50 %，並添加總體積0.5 % 的PPF與1.0 % 的CSW，此配比取代PC比例達50 %，3D列印工藝下的28天抗壓與抗彎強度高達88.9 MPa及13.6 MPa且具有韌性，相較於其他研究，永續材料取代PC比例提升3 % ~ 38 %、抗壓強度提升14 % ~ 154 %、抗彎強度提升65 % ~ 185 %，可進一步降低混凝土的二氧化碳排放並提升強度，以更少量的材料達到結構強度要求，具有優異的永續性及力學性能。;3D printing concrete technology is an automated construction method that offers greater geometric freedom and lower material consumption compared to traditional casting methods. This study employs various types of sustainable materials to replace conventional materials at high ratios and incorporates fibers to enhance performance, creating sustainable 3D printed fiber-reinforced concrete. The fresh properties, hardened properties, and drying shrinkage of the concrete are tested to evaluate the compatibility and engineering properties of sustainable materials and fibers in 3D printing concrete.
This research is divided into three phases: "Effects of Sustainable Cementitious Materials on the Engineering Properties of Cement Paste," "Effects of Sustainable Materials on the Engineering Properties of 3D Printing Concrete," and "Effects of Fibers on the Engineering Properties of 3D Printing Concrete." The first phase investigates the impact of different sustainable cementitious materials (densified silica fume(SFD), undensified silica fume(SFU), fly ash(FA), ground granulated blast furnace slag(BF), limestone(LS), metakaolin(MK), paper sludge fly ash(PSFA), ultra-fine fly ash(RUFA), oyster shell powder(OSP), and calcium sulfate whisker(CSW)) on the fresh and engineering properties of cement paste at various resting times (0 min, 10 min, and 30 min). The second phase explores the effects of promising sustainable cementitious materials at different replacement ratios (30 %, 40 %, 50 %, and 60 %) for cement(PC), and the use of sustainable aggregates (manufactured sand(MS), and artificial sand(AS)) in 3D printing concrete, evaluating their impact on fresh properties, printability, hardened properties, and drying shrinkage, proposing mixtures that meet engineering properties and sustainability benefits. The third phase examines the impact of adding fibers (polyoxymethylene fiber (POMF), polypropylene fiber (PPF), carbon fiber (CF), and CSW) on the engineering properties of 3D printing concrete, designing composite fiber mixes based on different fibers characteristics, and evaluating the effectiveness and compatibility of composite fibers in improving 3D printing concrete.
The results of the first phase show that replacing 30 % of PC with SFD, SFU, FA, BF, MK, and RUFA does not affect printability and provides sufficient hydration capacity to maintain concrete strength. The second phase results indicate that using promising sustainable cementitious materials (SFD, FA, and BF) and sustainable aggregates in 3D printing concrete meets printability standards after adding appropriate admixtures, though flow values vary by material, with shape retention rates above 85 %. Considering the sustainability and strength of the mix, the optimal replacement ratio of sustainable cementitious materials for PC is 50 %; higher ratios decrease strength, while lower ratios lack sustainability. For drying shrinkage, suitable replacement ratios of different sustainable cementitious materials reduce specimen shrinkage, with FA performing best, followed by BF, while excessive SFD (> 60 %) increases shrinkage. Among the sustainable aggregates, AS has good shape retention but low strength and serious volume stability issues, MS performs well in both shape retention and strength, making it suitable for 3D printing concrete. The third phase results show that different fibers affect mechanical properties in various ways: POMF and PPF enhance concrete toughness but reduce strength, while CF and CSW increase strength but do not improve toughness. For drying shrinkage, adding up to 1.5 % POMF and 1.0 % CF reduces shrinkage rate, while PPF and CSW increase shrinkage with higher content. The 3D printing process results in lower concrete strength compared to traditional casting methods and introduces anisotropy. For compressive strength, the anisotropy without fiber addition is observed as X > Z > Y, and with fiber addition as X > Z ≒ Y. In terms of flexural strength, the anisotropy consistently shows Y > X. However, the overall coefficient of variation remains close to 0, indicating minimal strength differences across different directions. Based on the test results, the final proposed mix is a 1:1 volume ratio replacement of PC with SFD and FA, totaling 50 %, with the addition of 0.5 % PPF and 1.0 % CSW by volume. This mix achieves a 50 % replacement ratio of PC, with 28-day compressive and flexural strengths reaching 88.9 MPa and 13.6 MPa respectively, and improved toughness. Compared to other studies, the replacement ratio of sustainable materials increased by 3 % ~ 38 %, compressive strength improved by 14 % ~ 154 %, and flexural strength increased by 65 % ~ 185 %, further reducing CO2 emissions from concrete while enhancing mechanical properties. This mix achieves structural strength requirements with less material, offering excellent sustainability and mechanical properties. |
