Interlayer strength loss in 3D printed concrete due to time-gap-induced macroporosity

IF 8 1区工程技术 Q1 CONSTRUCTION & BUILDING TECHNOLOGY

Construction and Building Materials Pub Date : 2025-10-07 DOI:10.1016/j.conbuildmat.2025.143924

Rui Luo , Bin Sun , Xiangpeng Fei , Hongjian Du

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引用次数: 0

Abstract

Interlayer bond integrity governs the structural reliability of 3D printed concrete and is degraded by pauses between layers. This study used X-ray computed tomography to quantify interlayer pore morphology and conducted mechanical tests in splitting, shear, and flexure to measure interlayer strength. Pore statistics were used to parameterize a random pore reconstruction model that resolves stress fields and predicts strength, and its predictions agreed with measurements within 15%. The results showed that a 10 min gap transformed isolated pores into a 3 mm thick interlayer macro void band, which accelerated crack initiation and coalescence and caused pronounced strength loss. Longer gaps from 30 to 120 min promoted lateral proliferation and clustering of macro voids, after which shear and flexural strengths decreased approximately linearly with interlayer porosity, while splitting strength approached a plateau. For this concrete system, maintaining the time gap below 10 min or the interlayer macroporosity below 2% is advisable to preserve interlayer strength. Simulations also indicate a size effect driven by dense macro void clustering, with a fourfold increase in specimen size reducing predicted flexural strength by up to 14.2%.

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三维打印混凝土中由时间间隙引起的大孔隙导致的层间强度损失

层间粘结完整性决定了3D打印混凝土的结构可靠性，并因层间的停顿而降低。本研究使用x射线计算机断层扫描来量化层间孔隙形态，并进行劈裂、剪切和弯曲力学测试来测量层间强度。孔隙统计数据用于参数化随机孔隙重建模型，该模型可以解析应力场并预测强度，其预测结果与测量结果的一致性在15%以内。结果表明：10 min的间隙将孤立孔隙转变为3 mm厚的层间宏观空隙带，加速了裂纹的萌生和合并，造成了明显的强度损失；在30 ~ 120 min范围内，较长的空隙促进了宏观空隙的横向扩散和聚集，之后剪切和抗弯强度随层间孔隙度近似线性下降，而劈裂强度趋于平稳。对于该混凝土体系，为保持层间强度，宜将时间间隔控制在10 min以下或层间宏观孔隙率控制在2%以下。模拟还表明，由密集的宏观孔隙聚集驱动的尺寸效应，试件尺寸增加四倍，预测抗弯强度降低高达14.2%。

本文章由计算机程序翻译，如有差异，请以英文原文为准。

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来源期刊

Construction and Building Materials 工程技术-材料科学：综合

CiteScore

13.80

自引率

21.60%

发文量

3632

审稿时长

82 days

期刊介绍： Construction and Building Materials offers an international platform for sharing innovative and original research and development in the realm of construction and building materials, along with their practical applications in new projects and repair practices. The journal publishes a diverse array of pioneering research and application papers, detailing laboratory investigations and, to a limited extent, numerical analyses or reports on full-scale projects. Multi-part papers are discouraged. Additionally, Construction and Building Materials features comprehensive case studies and insightful review articles that contribute to new insights in the field. Our focus is on papers related to construction materials, excluding those on structural engineering, geotechnics, and unbound highway layers. Covered materials and technologies encompass cement, concrete reinforcement, bricks and mortars, additives, corrosion technology, ceramics, timber, steel, polymers, glass fibers, recycled materials, bamboo, rammed earth, non-conventional building materials, bituminous materials, and applications in railway materials.