碱激发秸秆灰渣改良膨胀土试验研究

通过室内试验,探讨利用碱激发秸秆灰渣改良膨胀土的可行性及改良效果。试验研究了秸秆灰渣、碱激发秸秆灰渣改良膨胀土的基本工程性质指标、击实特性、胀缩特性及无侧限抗压强度的影响特征。试验研究结果表明,随着秸秆灰渣的增加或者碱溶液浓度的增加,膨胀土的塑性指数、自由膨胀率、膨胀量与膨胀力逐渐减小,这说明掺秸秆灰渣可有效降低膨胀土的胀缩性。击实样经养护后的膨胀试验结果表明,随着养护龄期的增加,膨胀土的膨胀力明显减小。无侧限抗压强度试验结果表明:没有经过养护的土样,碱激发秸秆灰渣对无侧限抗压强度的影响不够明显;经过7 d养护后,随着掺秸秆灰渣的增加,土样的无侧限抗压强度具有一定程度的提高,并且无侧限抗压强度存在一个峰值点。

Experimental on improvement of expansive soils with alkali activated straw ash

In this paper, the feasibility and improvement effect of alkali activated straw ash on expansive soil was studied in the laboratory test. In this test, the basic engineering properties, compaction characteristics, swelling shrinkage characteristics and the influence of unconfined compressive strength of expansive soil with straw ash and alkali activated were studied. The test results show that the plasticity index, free swell index, swell potential, swelling pressure and axial shrinkage percent decrease with the increase of straw ash or alkali activated straw ash content. These indicate the effectiveness of straw ash in reducing the swell-shrinking potential of the soils. It is found that with the increase of the curing time, the 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 straw ash alone or alkali activated. However, 7 days curing brings a remarkable increase in the unconfined compressive strength.