This study revealed the relationship among early-age thixotropic behavior, air-phase microstructure, and fracture properties of the interlayer region in additively manufactured (AM) cementitious materials. Cementitious materials were designed and characterized to possess distinctive rheological properties and were additively manufactured into cementitious specimens. The effects of thixotropy and printing time interval on the volume, size and aspect ratios of air-phase clusters and on their statistical distributions were analyzed comprehensively through three-dimensional micro-computed tomography. Also determined were the effects of thixotropy and printing time interval on the fracture properties of the interlayer regions. Based on the experimental evidence, the underlying mechanisms of how the time-dependent thixotropic behavior of AM cementitious materials impacts interlayer microstructure and fracture properties were discussed. The results shed light on material design strategies, through tailoring the fresh-state thixotropy of AM cementitious materials, to mitigate the sensitivity of their hardened-state properties to printing parameters.

中文翻译：

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触变性在增材制造胶凝材料层间微观结构和性能中的作用

这项研究揭示了增材制造（AM）胶凝材料的早期触变行为、气相微观结构和层间区域断裂性能之间的关系。水泥材料经过设计和表征，具有独特的流变特性，并增材制造成水泥样本。通过三维微计算机断层扫描综合分析了触变性和打印时间间隔对气相团簇体积、尺寸、长宽比及其统计分布的影响。还确定了触变性和打印时间间隔对层间区域断裂性能的影响。基于实验证据，讨论了AM胶凝材料随时间变化的触变行为如何影响层间微观结构和断裂性能的潜在机制。研究结果揭示了材料设计策略，通过调整增材制造水泥材料的新鲜状态触变性，以减轻其硬化状态特性对打印参数的敏感性。