Diffusivity and micro-hardness of blended cement materials exposed to external sulfate attack
Diffusivity and micro-hardness of blended cement materials exposed to external sulfate attack
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DOI：
10.1016/j.cemconcomp.2011.08.016
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发表时间：
2012
影响因子：
10.5
通讯作者：
A. Bonakdar;B. Mobasher;N. Chawla
中科院分区：
文献类型：
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作者：
A. Bonakdar;B. Mobasher;N. Chawla
水泥基材料中的许多降解过程包括一种或多种化学物质扩散到混凝土中以及随后改变微观结构的化学和物理性质的化学反应。外部硫酸盐侵蚀主要通过耦合扩散反应机制来描述，该机制导致硬化水泥成分分解和浆体开裂。本文讨论了混合水泥基复合材料中扩散特性和外部硫酸盐侵蚀中的化学变化的重要性。开发了一种基于粒子诱导 X 射线发射 (PIXE) 的方法来测量无损测试方法中的扩散特性。定量能量色散光谱（EDS）和显微硬度技术也被用来研究硫酸盐侵蚀造成的化学和机械变化。测定了浆料和砂浆混合物的扩散系数和反应速率，结果表明与对照混合物的浆料相比，砂浆中的扩散速率更高，硬度值更低。用粉煤灰部分替代水泥改善了运输性能并降低了暴露于硫酸盐侵蚀时的损坏程度。
Many degradation processes in cement based materials include the diffusion of one or more chemical species into concrete and consequent chemical reactions which alter the chemical and physical nature of the microstructure. External sulfate attack is mostly described by a coupled diffusion–reaction mechanism which leads to the decomposition of hardened cement constituents and cracking of the paste. This paper discusses the significance of diffusion properties and chemical changes in external sulfate attack in blended cement based composites. A method based on Particle Induced X-ray Emission (PIXE) was developed to measure the diffusion properties in a non-destructive test method. Quantitative Energy Dispersive Spectrometry (EDS) and micro-hardness technique were also used to study the chemical and mechanical changes from sulfate attack. Diffusion coefficients and rates of reaction were determined for paste and mortar mixtures, showing higher diffusion rates and lower hardness values in mortar compared to paste for control mixtures. Partial replacement of cement with fly ash improved the transport properties and reduced the level of damage in exposure to sulfate attack.