Strength and drying shrinkage of reactive MgO modified alkali-activated slag paste
Strength and drying shrinkage of reactive MgO modified alkali-activated slag paste
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DOI：
10.1016/j.conbuildmat.2013.10.081
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发表时间：
2014-01-31
影响因子：
7.4
通讯作者：
Al-Tabbaa, Abir
中科院分区：
文献类型：
--
作者：
Jin, Fei;Gu, Kai;Al-Tabbaa, Abir
传统的碱矿渣（AAS）水泥具有显著的干燥收缩，这阻碍了其广泛应用。本文研究了使用工业活性MgO来降低MS的干燥收缩的潜力。两种不同的活性MgO以2.5- 7.5wt%的含量被添加到矿渣中，其被氢氧化钠和水玻璃活化。测定了这些活性MgO改性MS（MAAS）浆体的强度和干燥收缩，直至90天。结果表明，高活性MgO对AAS的早期水化有促进作用，而中等活性MgO对AAS的早期水化作用不大。高活性MgO能显著降低混凝土的干燥收缩，但在干燥条件下也会产生严重的开裂。中活性MgO仅在一个月后表现出明显的减缩效果，但水泥安定性得到改善。通过X射线衍射、热重分析和扫描电子显微镜技术对水化产物进行分析，结果表明Mg主要以类水滑石相形式存在。它的结论是，固化条件和类水滑石相的形成时间和它们的数量是至关重要的开发强度和收缩减少性能的MAAS，这是高度依赖于反应性和含量的活性氧化镁。皇冠版权所有（C）2013由爱思唯尔有限公司出版。保留所有权利。
Conventional alkali-activated slag (AAS) cements suffer from significant drying shrinkage which hinders their widespread application. This paper investigates the potential of using commercial reactive MgO to reduce the drying shrinkage of MS. Two different reactive MgOs were added at a content of 2.5-7.5 wt% of the slag, which was activated by sodium hydroxide and water-glass. The strength and the drying shrinkage of those reactive MgO modified MS (MAAS) pastes were measured up to 90 days. It is found that MgO with high reactivity accelerated the early hydration of AAS, while MgO with medium reactivity had little effect. The drying shrinkage was significantly reduced by highly reactive MgO but it also generated severe cracking under the dry condition. On the other hand, medium-reactive MgO only showed observable shrinkage-reducing effect after one month, but the cement soundness was improved. The hydration products, analysed by X-ray diffraction, thermogravimetric analysis and scanning electron microscopy techniques, showed that Mg was mainly incorporated in the hydrotalcite-like phases. It is concluded that the curing conditions and the time of hydrotalcite-like phases formation and their quantity are crucial to the developed strength and shrinkage reduction properties of MAAS, which are highly dependent on the reactivity and content of reactive MgO. Crown Copyright (C) 2013 Published by Elsevier Ltd. All rights reserved.