| 摘要: | 3D 列印混凝土是利用增材製造技術逐堆疊成複雜的混凝土結構，對於材料與列印 工藝的要求極高。本研究主要以調整化學外加劑、砂膠比及纖維參數進行測試，分別透 過工作性、可列印性、力學行為及體積穩定性等方面加以探討，評估不同配比設計對 3D 列印混凝土的工程性質之影響。
本研究分為「化學外加劑對 3D 列印水泥基體工程性質之影響」、「砂膠比對 3D 列 印混凝土之工程性質之影響」及「纖維種類對 3D 列印纖維混凝土工程性質之影響」三 個階段進行探討，第一階段主要評估不同類型或型號之化學外加劑對 3D 列印水泥基體 之影響，並根據其測試結果提出適用於 3D 列印混凝土之化學外加劑及使用比例;第二 階段探討使用不同砂膠比(0.5 ~ 1.5)，對 3D 列印混凝土之工作性與可列印性之關係，並 探討砂膠比對 3D 列印混凝土硬固性質之影響;第三階段則透過纖維的類型(聚甲醛、聚 丙烯、碳及玄武岩纖維)、含量(0.5 % ~ 1.5 %)及長度(6 ~ 12 mm)變化對 3D 列印纖維混 凝土的工程性質影響，評估不同纖維應用於 3D 列印纖維混凝土之匹配性及適用性。
結果顯示，黏度改質劑可對 3D 列印混凝土之觸變性提供顯著改善，並以固含量與 減水率分別為 17.5 與 25 % 之複合型聚羧酸減水劑(SPD)搭配複合型黏度改質劑(CVMA) 較具適用性，且 CVMA 之添加量為膠結材料重量比之 0.5 % 時效果最佳。在 3D 列印混 凝土之新拌階段方面，砂膠比的變化將影響 3D 列印混凝土之可列印範圍，流度與保型 率需分別處於 50 % ~ 60 % 及 86.5 % ~ 91.5 % 範圍內時方可滿足其可列印性。在硬 固階段可發現，相較於傳統灌漿，以 3D 列印方式製作之混凝土試體存在強度損失並有 各向異性存在，其中，各面抗壓強度之關係為 X 面 > Y 面 ≈ Z 面，而抗彎強度之關 係則為 Y 面 ≈ Z 面 < X 面。在與砂膠比之關係方面，3D 列印混凝土之砂膠比在提升 至 1.5 時將對力學性質將造成負面影響，但其乾燥收縮量則隨砂膠比的提升而出現顯著 改善。同時發現，3D 列印混凝土會因纖維之性質不同而在強度發展趨勢上存在相異。其 中，碳纖維可有效改善強度損失，且強度表現隨摻量增加而提升，並可增加彈性階段之 位移量;聚丙烯纖維之強度表現僅次於碳纖維，且其同樣隨摻量增加而提升，並可有效
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提升混凝土在開裂後之韌性表現;聚甲醛纖維與玄武岩纖維則較不利於 3D 列印混凝土 之強度發展，其中，玄武岩纖維之強度表現則呈現先上升後下降之趨勢，且在列印過程 中極易在噴頭處堆積而造成擠出困難，而聚甲醛纖維造成之強度損失隨摻量增加而顯著， 但其在混凝土之體積穩定性方面可起正向作用。此外，不論纖維種類，增加纖維長度皆 可能造成 3D 列印混凝土之強度削減，並導致乾燥收縮提升。;3D printing concrete is a complex concrete structure that is stacked one by one using additive manufacturing technology, which has extremely high requirements for materials and printing technology. This study mainly tests the adjustment of chemical admixtures, cement ratio and fiber parameters, discusses the workability, printability, mechanical behavior and volume stability respectively, and evaluates the effect of different ratio designs on 3D printing concrete. The impact of the nature of the project.
This research is divided into "Effects of chemical admixtures on the engineering properties of 3D printing cement matrix", "Effects of sand-binder ratio on the engineering properties of 3D printing concrete" and "Effects of fiber types on the engineering properties of 3D printing fiber-reinforced concrete" The discussion will be carried out in three stages. The first stage mainly evaluates the impact of different types or types of chemical admixtures on the 3D printing cement matrix, and proposes the chemical admixtures and usage ratios suitable for 3D printing concrete based on the test results; the second stage in the first stage, different sand binder glue ratios (0.5 ~ 1.5) were used to propose the relationship between the workability and printability of 3D printing concrete, and to explore the impact of the sand binder ratio on the hardend properties of 3D printing concrete; the third stage was to use the effect of fiber type (polyoxymethylene, polypropylene, carbon and basalt fiber), content (0.5 % ~ 1.5 %) and length (6 ~ 12 mm) on the engineering properties of 3D printing fiber concrete, to evaluate the application of different fibers in compatibility and applicability of 3D printing fiber concrete.
The results show that the viscosity modifier can significantly improve the thixotropy of 3D printing concrete, and the composite polycarboxylate superplasticizer (SPD) with a solid content of 17.5% and a water reducing rate of 25% is combined with a composite
viscosity modifier Additive (CVMA) is more applicable, and the effect is best when the
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amount of CVMA added is 0.5% of the weight ratio of the cementitious material. In the fresh mixing stage of 3D printing concrete, the change of sand binder ratio will affect the printable range of 3D printing concrete, and the fluidity and shape retention rate should be in the range of 50% ~ 60% and 86.5% ~ 91.5% respectively only then can its printability be satisfied. In the hardening stage, it can be found that compared with traditional casting, the concrete specimen produced by 3D printing has strength loss and anisotropy. Among them, the relationship between the compressive strength of each surface is X-plane > Y- plane ≈ Z surface, and the relationship of flexural strength is Y surface ≈ Z surface < X surface. In terms of the relationship with the sand-binder ratio, when the sand-binder ratio of 3D printing concrete is increased to 1.5, the mechanical properties will be negatively affected, but its drying shrinkage will be significantly improved with the increase of the sand-binder ratio. At the same time, it was found that 3D printing concrete will have different strength development trends due to different properties of fibers. Among them, carbon fiber can effectively improve the strength loss, and the strength performance increases with the increase of the content, and can increase the displacement of the elastic stage; the strength performance of the polypropylene fiber is second only to the carbon fiber, and it also increases with the increase of the content. It can effectively improve the toughness of concrete after cracking; POM fiber and basalt fiber are not conducive to the strength development of 3D printing concrete. Among them, the strength performance of basalt fiber shows a trend of rising first and then falling, and during the printing process it is very easy to accumulate at the nozzle and cause extrusion difficulties, and the strength loss caused by polyoxymethylene fibers increases significantly with the increase of the content, but it can play a positive role in the volume stability of concrete. In addition, regardless of the fiber type, increasing the fiber length may reduce the strength of 3D printing concrete and lead to increased drying shrinkage. |
