干湿循环条件下CFG固化膨胀土强度特性研究

Strength characteristics of CFG-cured expansive soil under dry and wet cycle conditions

为研究水泥-粉煤灰-脱硫石膏(CFG)复合材料改良膨胀土的强度及干湿循环耐久性,制备CFG改良土进行强度试验及干湿循环试验。测试分析不同龄期CFG改良土的无侧限抗压强度及不同干湿循环次数下的表观状况、质量损失率和强度并与水泥改良土进行对比。结果表明:粉煤灰和脱硫石膏均可提高水泥固化土的强度,脱硫石膏能够增强早期强度而粉煤灰对长期强度的增强效果更明显,固化土的强度随龄期的增加而增加;干湿循环后,水泥固化土的强度随循环次数的增加而降低,其质量先增加后降低且表观破坏程度逐渐增大;CFG复合固化土的强度随循环次数的增大先增加后降低,其质量减小缓慢;与水泥固化土相比,CFG复合固化土的抗干湿循环能力更好。

In order to study the strength and wetting-drying cycle durability of the expansive soil improved by cement-fly ash-desulfurized gypsum(CFG)composite,the strength test and wetting-drying cycle test of the improved soil were carried out in the laboratory.The unconfined compressive strength of different age CFG improved soil under standard curing was tested.The apparent state,mass loss rate and unconfined compressive strength of the CFG improved soil under different wetting-drying cycles were studied and compared with that of the cement improved soil.The results show that fly ash and desulfurized gypsum can improve the strength of cement stabilized soil.Desulfurized gypsum can enhance the early strength,while fly ash can enhance the long-term strength more obviously.The strength of solidified soil increases with the increase of curing age.After the drying and wetting cycles,the strength of cement stabilized soil decreases with the increase of cycles,and its quality increases first and then decreases.The strength of the CFG composite solidified soil increases first and then decreases relatively with the increase of the cycle number,while the mass decreases slowly with the increase of the cycle number.Compared with cement stabilized soil,CFG composite stabilized soil has better ability of wetting-drying cycle resistance.