Dhandapani Yuvaraj, Machner Alisa, Wilson William, Kunther Wolfgang, Afroz Sumaiya, Kim Taehwan, Zunino Franco, Joseph Shiju, Kanavaris Fragkoulis, Castel Arnaud, Thienel Karl-Christian, Irassar Edgardo F, Bishnoi Shashank, Martirena Fernando, Santhanam Manu
School of Civil Engineering, University of Leeds, Leeds, UK.
Technical University of Munich, TUM School of Engineering and Design, Department of Materials Engineering, Professorship for Mineral Construction Materials, Munich, Germany.
Mater Struct. 2024;57(7):154. doi: 10.1617/s11527-024-02426-7. Epub 2024 Jul 23.
In this review by TC- 282 CCL, a comprehensive examination of various facets of chloride ingress in calcined clay-based concrete in aggressive chloride-rich environments is presented due to its significance in making reinforced concrete structures susceptible to chloride-induced corrosion damages. The review presents a summary of available literature focusing on materials characteristics influencing the chloride resistance of calcined clay-based concrete, such as different clay purity, kaolinite content and other clay minerals, underscoring the significance of pore refinement, pore solution composition, and chloride binding mechanisms. Further, the studies dealing with the performance at the concrete scale, with a particular emphasis on transport properties, curing methods, and mix design, are highlighted. Benchmarking calcined clay mixes with fly ash or slag-based concrete mixes that are widely used in aggressive chloride conditions instead of OPC is recommended. Such comparison could extend the usage of calcined clay as a performance-enhancing mineral admixture in the form of calcined clay or LC2 (limestone-calcined clay). The chloride diffusion coefficient in calcined clay concrete is reported to be significantly lower (about 5-10 times in most literature available so far) compared to OPC, and even lower compared to fly ash and slag-based concrete at early curing ages reported across recent literature made with different types of cements and concrete mixes. Limited studies dealing with reinforcement corrosion point out that calcined clay delays corrosion initiation and reduces corrosion rates despite the reduction in critical chloride threshold. Most of these results on corrosion performance are mainly from laboratory studies and warrant field evaluation in future. Finally, two case studies demonstrating the application of calcined clay-based concrete in real-world marine exposure conditions are discussed to showcase the promising potential of employing low-purity calcined clay-based concrete for reducing carbon footprint and improving durability performance in chloride exposure.
在TC - 282 CCL的这篇综述中，鉴于氯化物侵入对使钢筋混凝土结构易受氯化物诱导的腐蚀破坏具有重要意义，对富含侵蚀性氯化物环境中煅烧粘土基混凝土中氯化物侵入的各个方面进行了全面研究。该综述总结了现有文献，重点关注影响煅烧粘土基混凝土抗氯化物性能的材料特性，如不同的粘土纯度、高岭土含量和其他粘土矿物，强调了孔隙细化、孔隙溶液组成和氯化物结合机制的重要性。此外，还突出了在混凝土尺度上研究其性能的相关研究，特别强调了传输性能、养护方法和配合比设计。建议将煅烧粘土混合料与广泛用于侵蚀性氯化物条件下的粉煤灰或矿渣基混凝土混合料进行对比，而不是与普通硅酸盐水泥（OPC）对比。这样的比较可以扩大煅烧粘土作为性能增强矿物掺合料的使用范围，其形式可以是煅烧粘土或LC2（石灰石 - 煅烧粘土）。据报道，与OPC相比，煅烧粘土混凝土中的氯化物扩散系数显著更低（在目前大多数文献中约低5 - 10倍），与近期不同类型水泥和混凝土混合料的文献报道的早期养护龄期的粉煤灰和矿渣基混凝土相比甚至更低。关于钢筋腐蚀的有限研究指出，尽管临界氯化物阈值降低，但煅烧粘土会延迟腐蚀起始并降低腐蚀速率。这些关于腐蚀性能的大多数结果主要来自实验室研究，未来需要进行现场评估。最后，讨论了两个案例研究，展示了煅烧粘土基混凝土在实际海洋暴露条件下的应用情况，以说明使用低纯度煅烧粘土基混凝土在减少碳足迹和提高氯化物暴露环境下耐久性方面的潜在前景。
