Cold joints, formed due to interruptions in the concrete placement process, significantly impact the mechanical behavior of concrete structures. This study comprehensively examines the detrimental effects of cold joints on the mechanical properties of concrete. Field and laboratory experiments were conducted to evaluate the compressive and flexural strength, modulus of elasticity, toughness, and fracture energy of concrete specimens containing cold joints. Compressive tests were performed at a loading rate of 0.5MPa/s, while flexural tests were conducted at a loading rate of 0.05MPa/s. The influence of cold joint orientation (vertical, horizontal, or angled) on crack formation, failure mechanisms and mechanical behavior was examined. Microstructural analysis was employed to understand the underlying mechanisms of strength reduction. Additionally, numerical modeling was utilized to simulate the behavior of concrete with cold joints. The test results indicated that if a cold joint is necessary in the compressive zone, it should be located at a position of 0.5 and at an angle of 90°. For the flexural zone, a cold joint location of 0.75 and an angle of 45° were determined to be optimal. The results of this study offer valuable insights into the effects of cold joints on concrete structures and contribute to the development of strategies to mitigate their adverse effects.

中文翻译：

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混凝土中冷接缝位置和角度影响的试验和数值研究


由于混凝土浇筑过程中断而形成的冷接缝会显著影响混凝土结构的机械性能。本研究全面研究了冷缝对混凝土力学性能的不利影响。进行了现场和实验室实验，以评估包含冷接缝的混凝土试件的抗压强度和弯曲强度、弹性模量、韧性和断裂能。压缩试验以 0.5MPa/s 的加载速率进行，弯曲试验以 0.05MPa/s 的加载速率进行。研究了冷接头方向（垂直、水平或倾斜）对裂纹形成、失效机制和机械行为的影响。采用微观结构分析来了解强度降低的潜在机制。此外，还利用数值建模来模拟具有冷接缝的混凝土的行为。试验结果表明，如果在压缩区需要冷接头，则应位于 0.5 的位置和 90° 的角度。对于弯曲区，确定 0.75 的冷接缝位置和 45° 的角度是最佳的。这项研究的结果为冷接缝对混凝土结构的影响提供了有价值的见解，并有助于制定减轻其不利影响的策略。