改性粉煤灰材料固沙特性试验研究

Experimental study on sand fixation characteristics of modified fly ash materials

粉煤灰是火力发电的主要废弃物,在中国西部地区广泛存在,受交通影响,处置成本高,西部宁夏甘肃地区沙漠化问题严重,基于两者供需关系开展粉煤灰改性材料固沙应用研究。基于固沙效果制定参考固沙标准,针对改性粉煤灰固沙材料,通过单轴抗压强度试验、含水率试验、扫描电镜试验(SEM)、X射线衍射试验(XRD)、剪切试验等多种分析方法对改性粉煤灰材料的力学性质、水化产物和微观结构进行研究。结果表明,改性粉煤灰材料单轴抗压强度和胶结效果均得到显著提高,改性粉煤灰材料水化后形成的水化硅酸钙凝胶是解释保水性差异的关键;10%碱激发剂改性粉煤灰胶结体黏聚力提升为原来的3倍以上,30%镁渣改性粉煤灰胶结体抗剪强度显著提高。建议采用低剂量碱激发剂(2.5%左右)或高剂量(>30%)镁渣改性粉煤灰,并适当提高灰沙比,以获得更好的经济效益和固沙效果。

Fly ash is a byproduct of thermal power generation that requires proper disposal.While it is abundant in western China,transportation and disposal costs can be significant.Furthermore,the regions of western Ningxia and Gansu are facing a severe desertification problem.This research aims to explore the potential of fly ash modified materials for sand fixation,while considering the balance between supply and demand.To develop reference and fixation standards based on the effect of sand fixation,the mechanical properties,hydration products,and microstructure of modified fly ash sand fixation materials were studied through various analytical methods,including uniaxial compressive strength test,water content test,scanning electron microscope test(SEM),X-ray diffraction test(XRD),and shear test.The results suggest a noteworthy enhancement in the uniaxial compressive strength and cementation effect of the modified fly ash materials.The hydrated calcium silicate gel formed after the hydration of the modified fly ash materials appears to be the key factor in explaining the difference in water retention.Additionally,the cohesive force of the 10%alkali exciter-modified fly ash cement increased to more than three times the original,and the shear strength of the 30%magnesium slag-modified fly ash cement was significantly improved.The article suggests considering the use of a low-dose alkali exciter,approximately 2.5%,or a high-dose magnesium slag modified fly ash,greater than 30%,while adjusting the ash-to-sand ratio accordingly to optimize both economic benefits and sand fixation effects.