石灰-粉煤灰改良膨胀土试验

探讨利用粉煤灰、石灰粉煤灰作为添加剂改良合肥膨胀土的可行性与改良效果.试验研究了粉煤灰、石灰粉煤灰掺合物对膨胀土的基本工程性质指标、击实特性、胀缩性以及无侧限抗压强度的影响特征.试验研究结果表明,随着掺灰率的增加,膨胀土的塑性指数、活性指数、自由膨胀率、膨胀量、膨胀力与线缩率呈减小趋势,这说明掺粉煤灰可有效降低膨胀土的胀缩性.经过一定龄期养护后的击实样的膨胀试验结果表明,随着养护龄期的增加,膨胀土的膨胀量与膨胀力都有一定降低.无侧限抗压强度试验结果表明:没有经过养护的土样,粉煤灰对无侧限抗压强度的影响不明显;经过7d龄期养护后,随着掺粉煤灰率的增加,土样的无侧限抗压强度具有一定程度的增长,并且无侧限抗压强度存在一个峰值点.

Experiment on improvement of expansive clays with lime-fly ash

The swelling,swelling pressure and moisture dependent shear strength of expansive soils pose serious problems to civil engineers.Disposal of large quantities of fly ash,which is an industrial waste,poses an environmental problem.In this study,the potential use and effectiveness of fly ash without or with lime as an additive in improving expansive soils are evaluated.The test results show that the plasticity index,activity,free swell index,swell potential,swelling pressure and axial shrinkage percent decrease with the increase of fly ash or fly ash-lime content.These indicate the effectiveness of fly ash in reducing the swell-shrinking potential of the soils.It is found that with the increase of the curing time,the swell potential and swelling pressure reduce.The unconfined compressive strength test results show that there is no remarkable change in the unconfined compressive strength of the soils immediately treated with fly ash alone.However,7 days curing brings a remarkable increase in the unconfined compressive strength.