Mechanisms of efflorescence of alkali-activated slag

IF 10.8 1区工程技术 Q1 CONSTRUCTION & BUILDING TECHNOLOGY

Cement & concrete composites Pub Date : 2024-10-23 DOI:10.1016/j.cemconcomp.2024.105811

Chen Liu , Zhenming Li , Guang Ye

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引用次数: 0

Abstract

Efflorescence presents not only as a cosmetic concern but also as a structural issue, which impacts the performance of alkali-activated materials (AAMs). In this study, the mechanisms of efflorescence of alkali-activated slag (AAS) pastes are investigated. First, the efflorescence of AAS pastes with different alkali dosages (3 %, 5 % and 7 %), activator types (sodium hydroxide (NH) and sodium silicate (NS)), exposure atmospheres (ambient, N₂ and 0.2 vol% CO₂), and relative humidities (40 %, 60 % and 80 %) was observed. Subsequently, leaching tests were performed and the impacts of efflorescence on AAS pastes at different heights were studied. It was found that a lower relative humidity facilitated more rapid and severe efflorescence. The positioning of efflorescence products was dependent on the porosity of the matrix. Compared to NH pastes, NS pastes subjected to semi-contact water conditions were more vulnerable to cracking problems, which turned out to be exacerbated by the formation of efflorescence products. A new method to quantify efflorescence was developed and it corresponded well with both efflorescence observations and leaching experiments. Furthermore, a competitive reaction between Ca and Na in the presence of carbonate ions was identified. CaCO₃, a representative product of natural carbonation, was rarely found in the regions where efflorescence products (sodium carbonate) formed. Regarding compressive strength, NS pastes were more adversely affected by efflorescence than NH pastes.

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碱激活炉渣的风化机理

风化不仅是一个外观问题，也是一个结构问题，会影响碱活性材料（AAM）的性能。本研究探讨了碱活性矿渣（AAS）浆料的风化机理。首先，观察了不同碱用量（3%、5% 和 7%）、活化剂类型（氢氧化钠 (NH) 和硅酸钠 (NS)）、暴露气氛（环境、N2 和 0.2 vol.% CO2）和相对湿度（40%、60% 和 80%）下 AAS 浆料的风化现象。随后，进行了沥滤试验，并研究了不同高度的渗出对 AAS 浆料的影响。结果发现，相对湿度越低，风化越快、越严重。风化产物的位置取决于基质的孔隙率。与 NH 浆料相比，在半接触水条件下的 NS 浆料更容易出现开裂问题，而这些问题又会因风化产物的形成而加剧。研究人员开发了一种量化风化的新方法，该方法与风化观察和浸出实验结果十分吻合。此外，还确定了 Ca 和 Na 在碳酸根离子存在下的竞争反应。在形成风化产物（碳酸钠）的区域很少发现 CaCO3，而 CaCO3 是自然碳化的代表性产物。在抗压强度方面，NS 浆料比 NH 浆料更容易受到风化的不利影响。

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 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.