淤泥的有机质中含氧官能团易与水泥水化产生的铝和钙相结合,延缓水泥水化的进程,阻碍水泥发生硬化,影响水泥固化淤泥强度的形成。为消除有机质对水泥水化的不利影响,选择高铁酸钾作为外掺剂对淤泥进行预处理,通过无侧限抗压试验和直剪试验,研究高铁酸钾对水泥固化淤泥强度的影响规律,并利用扫描电子显微镜分析水泥固化淤泥的微观结构。研究结果表明:高铁酸钾预处理可有效提高水泥固化淤泥的无侧限抗压强度和抗剪强度,其原因在于淤泥中的有机质被高铁酸钾氧化分解,保证了水泥水化反应和火山灰反应的充分进行,利于水泥水化产物的生成。同时,高铁酸钾被有机质还原,游离的Fe(III)吸附在黏土颗粒表面上,减薄了扩散层厚度,引起了黏土颗粒的絮凝。高铁酸钾预处理,通过改变水泥固化淤泥的微观结构,从而提高水泥固化淤泥强度。
Abstract
The oxygen-containing functional group in organic matters of sludge is prone to combine with the aluminum and calcium produced by the hydration of cement, thus delaying the hydration process and hindering the hardening of cement. To eliminate the adverse impact of organic matters on cement hydration, we select potassium ferrate as an admixture for the pretreatment of sludge, and examine the changes in the strength of cement-stabilized sludge via unconfined compressive strength and direct shear strength tests; furthermore we look into the microstructure of cement-stabilized sludge using scanning electron microscope. Research findings suggest that pretreating by adding potassium ferrate could effectively improve the unconfined compressive strength and shear strength of cement-stabilized sludge because the organic matters in sludge are oxidized by potassium ferrate, which ensures the full progress of cement hydration reaction and volcanic ash reaction.Besides, potassium ferrate is reduced by organic matters. The adsorption of free Fe(III) onto clay particles surface thins the diffusion layer and gives rise to the flocculation of clay particles.In conclusion, potassium ferrate pretreatment improves the strength of cement-stabilized sludge by changing the microstructure of cement-stabilized sludge.
关键词
水泥固化淤泥 /
有机质 /
高铁酸钾 /
无侧限抗压强度 /
抗剪强度 /
扫描电子显微镜
Key words
cement-stabilized sludge /
organic matters /
potassium ferrate /
unconfined compressive strength /
shear strength /
scanning electron microscope
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基金
国家自然科学基金项目(4167020615);
国家自然科学基金青年基金项目(41602319)
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