Strength and drying shrinkage of slag paste activated by sodium carbonate and reactive MgO
Strength and drying shrinkage of slag paste activated by sodium carbonate and reactive MgO
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DOI：
10.1016/j.conbuildmat.2015.01.082
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发表时间：
2015-04-15
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;Al-Tabbaa, Abir
本文研究了Na2CO3和活性氧化镁复合作为高炉矿渣粉磨矿渣可持续激发剂的潜力。两种反应性不同的氧化镁的加入量为5-10%，Na2CO3的加入量为4%-8%。对活性矿渣浆体的强度和干燥收缩进行了90d的测试，发现活性氧化镁的最佳掺量为5%，而不考虑氧化镁的种类和碳酸钠的含量。活性较高的氧化镁显著提高了浆体的早期强度，但对90d的强度几乎没有影响，而活性较低的氧化镁对后期强度的影响在后期和低Na2CO3用量下更为明显。在干燥收缩方面，Na2CO3含量从4%增加到6%，干燥收缩显著降低，而从6%增加到8%，对干燥收缩的影响不大。X射线衍射和热重分析表明，水化产物主要为水化硅酸钙凝胶和类水滑石相，与常规碱激发矿渣水泥的水化产物相似。此外，由于碱化作用，在8%的Na2CO3糊中还形成了大量的方解石。结果表明，活性氧化镁和碳酸氢钠复配可以作为一种潜在的矿渣永续激发剂。(C)2015爱思唯尔有限公司。保留所有权利。
This paper investigates the potential of combining Na2CO3 and reactive MgO as a sustainable activator for ground granulated blastfurnace slag. Two very different reactivity MgOs were added at 5-10 % and the Na2CO3 content varied from 4% to 8% by the weight of slag. The strength and drying shrinkage of the activated slag pastes were tested up to 90 d. It was found that the optimum reactive MgO addition was 5% regardless of the MgO type and Na2CO3 content. MgO with the higher reactivity significantly increased the early strength of the paste but had almost no effect on the strength at 90 d. On the other hand, the effect of the lower reactivity MgO on the strength was more profound at later ages and low Na2CO3 dosage. In terms of drying shrinkage, increasing the Na2CO3 content from 4% to 6% caused a remarkable decrease of drying shrinkage while increasing it from 6% to 8% had negligible effect. X-ray diffraction and thermogravimetric analysis revealed that the major hydration products were calcium silicate hydrate gel and hydrotalcite-like phases, similar to those in conventional alkali-activated slag cements. There was also a large quantity of calcite formed especially in the 8% Na2CO3 pastes due to causticisation. It was concluded that the combination of reactive MgO and Na2CO3 could serve as a potential sustainable activator for slags. (c) 2015 Elsevier Ltd. All rights reserved.