Enhancing the rate-dependent cracking resistance of UHPC under mixed tensile-shear mode by calcined bauxite aggregate

IF 10.8 1区 工程技术 Q1 CONSTRUCTION & BUILDING TECHNOLOGY
Shaohua Li , Ole Mejlhede Jensen , Qingliang Yu
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引用次数: 0

Abstract

Calcined bauxite (CB) aggregate, characterized by porous microstructure and strong micromechanical property, has potential to mitigate macroscopic mechanical degradation of Ultra-high Performance Concrete (UHPC) from autogenous shrinkage microcracks. However, the rate-dependent cracking resistance of UHPC containing CB (UHPC-CB) under mixed-mode loading condition is not clear. Herein, the enhancing mechanism of CB upon rate-dependent cracking resistance of UHPC under mixed-mode loading is clarified from a multi-scale perspective. The results indicate that, at the microscale, CB not only leads to shorter microcracks due to physical constraint effects, but also results in a stronger ITZ compared to UHPC containing basalt aggregate (UHPC-BA), due to an internal curing effect thanks to its porous microstructure. At the mesoscale, the denser ITZ results in a higher fracture percentage of CB and more obviously an interlock effect in the case of shear stress condition. Consequently, at the macroscale, CB not only results in higher cracking resistance, especially in the case of shear loading, but also a higher dynamic increase factor value, attributed to the heterogenous micromechanical characteristics and stronger phases in CB.
煅烧铝土矿骨料增强超高性能混凝土拉剪混合模式下速率相关抗裂性能
煅烧铝土矿(CB)骨料具有多孔的微观结构和较强的微观力学性能,具有减缓超高性能混凝土(UHPC)自收缩微裂缝引起的宏观力学退化的潜力。然而,含CB的UHPC (UHPC-CB)在混合加载条件下的抗裂速率关系并不明确。本文从多尺度角度阐明了炭黑对混合模式加载下UHPC速率相关抗裂性能的增强机理。结果表明,在微观尺度上,与含玄武岩骨料的UHPC (UHPC- ba)相比,CB不仅由于物理约束作用导致微裂纹缩短,而且由于其多孔结构的内部固化效应,导致其具有更强的ITZ。在中尺度上,在剪切应力条件下,ITZ越致密,CB的破裂率越高,联锁效应越明显。因此,在宏观尺度上,黑炭黑不仅具有更高的抗裂性,特别是在剪切载荷下,而且由于黑炭黑的非均质细观力学特性和更强的相,其动态增加因子值也更高。
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
Cement & concrete composites
Cement & concrete composites 工程技术-材料科学:复合
CiteScore
18.70
自引率
11.40%
发文量
459
审稿时长
65 days
期刊介绍: Cement & concrete composites focuses on advancements in cement-concrete composite technology and the production, use, and performance of cement-based construction materials. It covers a wide range of materials, including fiber-reinforced composites, polymer composites, ferrocement, and those incorporating special aggregates or waste materials. Major themes include microstructure, material properties, testing, durability, mechanics, modeling, design, fabrication, and practical applications. The journal welcomes papers on structural behavior, field studies, repair and maintenance, serviceability, and sustainability. It aims to enhance understanding, provide a platform for unconventional materials, promote low-cost energy-saving materials, and bridge the gap between materials science, engineering, and construction. Special issues on emerging topics are also published to encourage collaboration between materials scientists, engineers, designers, and fabricators.
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