养护龄期对改良膨胀土无侧限抗压强度试验的影响

以湖北省宜昌市某公路膨胀土为研究对象,分别采用不同掺量的石灰、水泥、粉煤灰、风化砂对膨胀土进行改良。在经过7,14和28d标准条件养生后,进行无侧限抗压强度试验。试验结果表明,上述4种材料均能有效地提高改良膨胀土的无侧限抗压强度,在最初的14d内,水泥改良膨胀土的强度增长较为明显,后期随着养护龄期的增长,无侧限抗压强度增长速率较缓慢;石灰改良膨胀土的无侧限抗压强度值随着养护龄期的增加,一直保持近似直线形的增长趋势;粉煤灰改良膨胀土的无侧限抗压强度亦随着养护龄期的增长而呈直线增长,但其值小于石灰改良膨胀土;养护龄期对风化砂改良膨胀土的无侧限抗压强度影响很小。

Experiment on Impact of Curing Period on Unconfined Compressive Strength of Improved Expansive Soils

The expansive soil is studied as the object of the research in Yichang City, Hubei Province. Different content of lime, cement, coal fly ash and weathered sand are put into the expansive soil to modify it, then the unconfined compressive strength is tested under standard conditions with the days of 7, 14, 28 d. The research shows that the unconfined compressive strength can be improved in an effective way with the above four materials, the strength of expansive soil with cement grows obviously in the first 14 days, then the growth rate slows down with the curing age goes up; the unconfined compressive strength of expansive soil with lime is nearly in a linear growth trend with the curing age goes up; the unconfined compressive strength of expansive soil with coal fly ash is also in a linear growth trend, but the unconfined compressive strength is smaller than that of expansive soil with lime; the curing age has little effect on the unconfined compressive strength of expansive soil with weathered sand.