碱激发地聚物固化盐渍土微观结构研究

Microstructure of Saline Soil Solidified with Alkali-activated Geopolymer

碱激发地聚物胶凝材料能够有效固化硫酸盐渍土的根本机理在于改善固化土的微观结构。通过对比试验研究水玻璃、石灰粉煤灰和水玻璃石灰粉煤灰固化盐渍土的无侧限抗压强度和微观结构,阐述了水玻璃碱激发粉煤灰地聚物固化盐渍土微观结构效应。试验结果表明:石灰粉煤灰能够改善盐渍土颗粒级配,缩小孔径范围,降低孔隙体积,进而提高抗压强度;水玻璃能够胶结土颗粒成为团聚体,减小孔隙率和孔隙体积,其抗压强度受浓度影响较大;水玻璃石灰粉煤灰的孔隙特征不是最佳,但由于碱激发地聚物生成的水化凝胶物质填充了粒间孔隙,改善了颗粒胶结状况,抗压强度最高;碱激发地聚物固化盐渍土效果受碱激发反应程度的影响,反应程度越高,固化效果越好。

The fundamental mechanism by which alkali-excited geopolymer gelling material can effectively cure the sulfated soil lies in the improvement of the microstructure of the solidified soil.By comparing the unconfined compressive strength and microstructure of saline soil specimens solidified by water glass,lime-fly ash and water glass-lime fly ash,we examined the microstructure of saline soil solidified by water-glass alkali-activated fly ash geopolymer.Test results evinced that lime and fly ash together improved the particle gradation of saline soil,cut the pore size range,reduced the pore volume,and thus enhanced the compressive strength;water glass cemented the soil particles into agglomerates,reduced porosity and pore volume,and its compressive strength was markedly affected by concentration.The pore characteristics of saline soil solidified by water glass-lime fly ash were not optimal;but the compressive strength was the highest because hydration gel material formed by alkali-excited geopolymer filled the intergranular pores and improved the particle cementation condition.The solidification effect of alkali-excited geopolymer is affected by the degree of alkali-induced reaction.The higher the degree of reaction,the better the curing effect.