加气硅化黄土的微结构研究

Study on microstructure of CO_2-silicification grouted loess

采用扫描电镜、数字图像方法和表面积孔隙分析仪研究了天然黄土和固化龄期13,19,24 a加气硅化黄土的微结构和孔隙特征。结果表明:天然黄土和加气硅化黄土的微结构均以粒状架空结构为主;加气硅化黄土架空孔隙内充填有少量凝胶;这些凝胶附着在骨架颗粒表面,增大了颗粒间的接触面积。与天然黄土相比,硅化黄土孔径分布基本无变化,平均孔径、面积比和孔隙体积没有降低,但孔隙表面积从17.810 4 m2/g增加到27.473 5 m2/g。加气硅化黄土的机制是保持黄土架空孔隙基本不变,通过凝胶薄膜强化了黄土微结构中胶结物的强度,将骨架颗粒黏结成为一个空间网状整体,消除了黄土的湿陷性,并提高了其工程力学性能。

The microstructure and pore characteristics of natural loess and CO2-silicification loess are qualitatively and quantitatively studied based on the test results from scanning electron microscope and digital image analysis and accelerated surface area-porosimetry system.The silicified loess samples have been curing for 13 years,19 years and 24 years respectively.It is found that the main structure type of CO2-silicification remains the same as that for the natural loess.the silicate gel and calcium（magnesium） silicate gel have only filled in the pores and adsorbed the surface of frame grains resulting in increase of contact area of frame particle.Being compared with natural loess,CO2-silicification loess isn’t reduced in pore size distribution and average pore diameter and area porosity and pore volume;the pore surface area of CO2-silicification loess has been increased from 17.8104 m^2/g to 27.4735 m^2/g.CO2-silicification loess mechanism is that the open structure in silicification loess remains,but a film of gels reinforces the bond strength of cement in microstructure and forms three dimensional networks of frame grains resulting in the collapsibility of silicification loess disappearing;and mechanical properties of silicification loess are improved.