Abstract Concrete 3D printing is an application of 3D printing technology for the construction of concrete structural and non-structural elements. It is a rapid method of construction without the use of formwork, with minimum labor involvement and reduced material wastage. Curved walls and complex structures can be constructed by modifying the print path and controlling the rheological properties of concrete. The fusion of this technology with waste materials is necessary to reduce the problems associated with the recycling of wastes and to minimize CO2 emissions associated with the production of cement. In this study, two different municipal solid waste (MSW) incineration ashes (fly ash and bottom ash) were used to develop a concrete having rheological and hardened requirements of concrete used in 3D printing. Waste incinerator ashes were added as a substitute of ordinary Portland cement in concrete mix proportions. Flow table test and Gilmore needle test were used to measure the flow and setting time of concrete, respectively. Yield stress was measured by shear vane test. The buildability of ash containing printable concrete was simulated by comparing the vertical stresses due to the printing of concrete layers with the increase in the strength of the first stacked layer. Workability, open time, and buildability of the mix proportions were related to yield stress. The effect of adding waste incinerator ash upon the compressive strength was measured. The bond strength between layers at different printing time gaps was evaluated using bi-surface direct shear test. Experimental results showed that setting time promoting effect and initial yield stress enhancement by incinerated fly ash allows for a rapid construction speed with concrete 3D printing. This study concludes that incinerated fly ash can be successfully recycled in 3D printable concrete due to its favorable effects on rheology which are favorable for printing concrete.

中文翻译：

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在 3D 打印混凝土中使用城市固体废物焚烧灰

摘要 混凝土3D打印是3D打印技术在混凝土结构和非结构构件施工中的应用。这是一种无需使用模板的快速施工方法，劳动力参与最少，材料浪费减少。弯曲的墙壁和复杂的结构可以通过修改打印路径和控制混凝土的流变特性来构建。这项技术与废物材料的融合对于减少与废物回收相关的问题和最大限度地减少与水泥生产相关的二氧化碳排放是必要的。在这项研究中，使用两种不同的城市固体废物 (MSW) 焚烧灰（飞灰和底灰）来开发具有流变学和硬化要求的混凝土，用于 3D 打印。在混凝土配合比中加入垃圾焚烧炉灰作为普通硅酸盐水泥的替代品。分别采用流动表试验和吉尔摩针试验测量混凝土的流动性和凝结时间。通过剪切叶片试验测量屈服应力。通过比较由于混凝土层印刷引起的垂直应力与第一堆叠层强度的增加，模拟了含灰可印刷混凝土的可建造性。混合比例的可加工性、开放时间和可建造性与屈服应力有关。测量了添加垃圾焚烧炉灰对抗压强度的影响。使用双表面直接剪切试验评估不同印刷时间间隙下层间的粘合强度。实验结果表明，焚烧飞灰的凝结时间促进作用和初始屈服应力增强允许混凝土 3D 打印的快速施工速度。该研究得出的结论是，焚烧飞灰可以在 3D 可打印混凝土中成功回收，因为它对流变学有有利影响，有利于打印混凝土。