超细粉煤灰水泥改良膨胀土试验研究

Experimental study on expansive soil modified by ultrafine fly ash cement

通过超细粉煤灰水泥对膨胀土进行改良,研究了不同掺量超细粉煤灰水泥对膨胀土击实性能、自由膨胀率和力学性能的影响。研究结果表明:激发剂NaOH一定时,随着超细粉煤掺量的增加,膨胀土的最大干密度及最优含水量逐渐降低;超细粉煤灰水泥的掺入可以有效改善膨胀土的自由膨胀率,当超细粉煤灰水泥掺量为12%时,与素膨胀土相比,其自由膨胀率降低了83.06%,而养护龄期对自由膨胀率几乎没有影响。当超细粉煤灰水泥掺量为12%时,其膨胀土无侧限抗压强度最大,掺量超过12%之后,其抗压强度有所降低。随着超细粉煤灰水泥掺量的增加,膨胀土的三轴抗剪强度先增大后减小,建议超细粉煤灰水泥合理掺量为12%。试验研究成果可为改良膨胀土工程性质的研究人员提供参考。

Ultrafine fly ash was used to improve expansive soil.The effects of ultrafine fly ash with different contents on compaction,free expansion and mechanical properties of expansive soil were studied.The results show that the maximum dry density and optimal water content of expansive soil decrease gradually with the increase of the content of ultrafine pulverized coal when the initiator sodium hydroxide is constant.The incorporation of ultrafine fly ash can effectively improve the free expansion rate of expansive soil.When the content of ultrafine fly ash is 12%,the free expansion rate is 83.06%lower than that of the normal expansive soil,and the curing age has almost no effect on the free expansion rate.When the content of ultrafine fly ash is 12%,the unconfined compressive strength of the expansive soil is the largest,and the compressive strength decreases after the content of ultrafine fly ash exceeds 12%.With the increase of ultrafine fly ash content,the triaxial shear strength of expansive soil first increases and then decreases.It is suggested that the reasonable content of ultrafine fly ash is 12%.The experimental results can be used as a reference for the researchers to improve the engineering properties of expansive soils.