{"title":"Enhancing the rate-dependent cracking resistance of UHPC under mixed tensile-shear mode by calcined bauxite aggregate","authors":"Shaohua Li , Ole Mejlhede Jensen , Qingliang Yu","doi":"10.1016/j.cemconcomp.2025.105993","DOIUrl":null,"url":null,"abstract":"<div><div>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.</div></div>","PeriodicalId":9865,"journal":{"name":"Cement & concrete composites","volume":"159 ","pages":"Article 105993"},"PeriodicalIF":10.8000,"publicationDate":"2025-02-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"Cement & concrete composites","FirstCategoryId":"5","ListUrlMain":"https://www.sciencedirect.com/science/article/pii/S0958946525000757","RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q1","JCRName":"CONSTRUCTION & BUILDING TECHNOLOGY","Score":null,"Total":0}
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.
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.