温度改性水玻璃固化黄土机制研究

Mechanism of temperature-modification silicification grouted loess

硅化法是湿陷性黄土地基处理的主要化学方法之一,为了提高固化效果需要对水玻璃溶液进行改性。对温度改性水玻璃溶液固化黄土进行了试验研究,并通过化学组成和矿物成分分析、微观结构分析探讨了温度改性水玻璃固化黄土的机制。试验结果表明:在20～80℃范围内,随着温度的升高,水玻璃固化黄土的强度有明显提高;X射线衍射图谱中部分矿物衍射强度降低并出现密集低矮的非晶质物相峰群;SEM图像显示随着温度的升高凝胶薄膜增多;MIP(压汞试验)数据显示,随着温度的升高,孔隙表面积增大。水玻璃溶液固化黄土的强度随温度增加的机制在于:生成的非晶质物相和凝胶薄膜随着温度的升高而增加,促使最可几孔径的减小和小孔隙的增多,强化了骨架颗粒的连接强度,并将骨架颗粒黏结成为一个空间网状整体,从而改善了土体的强度。

Silicifrcation is one of the chemical methods of collapsible loess treatment. For better silicification effect, sodium silicate is modified by various methods. The mechanism of loess reinforced by temperature modified sodium silicate is studied. The physical component such as chemical composition and mineral composition, microstructure are tested and analyzed by carrying out X-ray diffraction （XRD）, scanning electron microscope（SEM） and mercury intrusion porosimetry （MIP）. The results show that the mechanical strength of loess is improved obviously with the temperature of sodium silicate increasing in the temperature range of 20-80~C. Diffraction intensity of parts of the mineral is reducing in the X-ray diffraction patterns; and low density amorphous phase peak groups appeared. The SEM images show that the gel films increased with the temperature of sodium silicate increasing. MIP data show that surface area of pores increased with the temperature increasing. The findings indicate that the increased amorphous phase and the gel films caused to decreased most probable pore size and increased small pores. The mechanism of loess reinforced by temperature modified sodium silicate is due to reinforcement of the bond strength of cement in microstructure and formation of three-dimensional networks of frame.