Lancellotti Isabella, Piccolo Federica, Nguyen Hoang, Mastali Mohammad, Alzeer Mohammad, Illikainen Mirja, Leonelli Cristina
Department of Engineering 'Enzo Ferrari', University of Modena and Reggio Emilia, Via Vivarelli 10, 41125 Modena, Italy.
Fibre and Particle Engineering Research Unit, University of Oulu, Pentti Kaiteran Katu 1, 90014 Oulu, Finland.
Polymers (Basel). 2021 Aug 10;13(16):2664. doi: 10.3390/polym13162664.
Alternative cementitious binders, based on industrial side streams, characterized by a low carbon footprint, are profitably proposed to partially replace Portland cement. Among these alternatives, alkali-activated materials have attracted attention as a promising cementitious binder. In this paper, the chemical stability of the matrix, in fiber-reinforced slag-based alkali-activated composites, was studied, in order to assess any possible effect of the presence of the reinforcement on the chemistry of polycondensation. For this purpose, organic fiber, cellulose, and an inorganic fiber, basalt, were chosen, showing a different behavior in the alkaline media that was used to activate the slag fine powders. The novelty of the paper is the study of consolidation by means of chemical measurements, more than from the mechanical point of view. The evaluation of the chemical behavior of the starting slag in NaOH, indeed, was preparatory to the understanding of the consolidation degree in the alkali-activated composites. The reactivity of alkali-activated composites was studied in water (integrity test, normed leaching test, pH and ionic conductivity), and acids (leaching in acetic acid and HCl attack). The presence of fibers does not favor nor hinder the geopolymerization process, even if an increase in the ionic conductivity in samples containing fibers leads to the hypothesis that samples with fibers are less consolidated, or that fiber dissolution contributes to the conductivity values. The amorphous fraction was enriched in silicon after HCl attack, but the structure was not completely dissolved, and the presence of an amorphous phase is confirmed (C-S-H gel). Basalt fibers partly dissolved in the alkaline environment, leading to the formation of a C-N-A-S-H gel surrounding the fibers. In contrast, cellulose fiber remained stable in both acidic and alkaline conditions.
基于工业副产品的具有低碳足迹特征的替代胶凝材料，被认为可部分替代波特兰水泥并具有经济效益。在这些替代材料中，碱激活材料作为一种有前景的胶凝材料已引起关注。本文研究了纤维增强矿渣基碱激活复合材料中基体的化学稳定性，以评估增强材料的存在对缩聚化学反应可能产生的任何影响。为此，选择了有机纤维（纤维素）和无机纤维（玄武岩），它们在用于激活矿渣细粉的碱性介质中表现出不同的行为。本文的新颖之处在于通过化学测量而非机械角度来研究固结情况。事实上，对起始矿渣在氢氧化钠中的化学行为进行评估是理解碱激活复合材料固结程度的前提。研究了碱激活复合材料在水中（完整性测试、标准化浸出测试、pH值和离子电导率）以及酸中（在乙酸中浸出和盐酸侵蚀）的反应活性。纤维的存在既不促进也不阻碍地质聚合过程，尽管含纤维样品中离子电导率的增加使人推测含纤维样品的固结程度较低，或者纤维溶解对电导率值有贡献。盐酸侵蚀后，无定形部分的硅含量增加，但结构并未完全溶解，且证实存在无定形相（C-S-H凝胶）。玄武岩纤维在碱性环境中部分溶解，导致在纤维周围形成C-N-A-S-H凝胶。相比之下，纤维素纤维在酸性和碱性条件下均保持稳定。
