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利用水蒸气吸附仪对石灰改性膨胀土进行水蒸气吸附试验,得出随着掺灰量的变化,膨胀土的吸水性先减小后增大,且在掺灰量为6%处取得最小值。为了研究引起膨胀土吸水性变化的主要原因,再对改性膨胀土进行氮气吸附试验,从而分析掺灰膨胀土孔隙结构的变化。研究发现,随着掺灰量的增加,BET微孔比表面积呈折线形变化,且在掺灰量为6%时取得最小值;中孔的累积容积随着掺灰量的增大而减小;随着掺灰量的增加,中孔孔径先增大后减小,且在掺灰量为6%处取得最大值。膨胀土的吸水性与中孔孔径的变化成负相关,且膨胀土的最佳掺灰量为6%。
The water vapor sorption meter was used to test the water vapor adsorption of lime-modified expansive soil. The results showed that the water absorption of expansive soil first decreased and then increased with the increase of ash content, and reached the minimum at 6% value. In order to study the main reason that caused the change of water absorption of expansive soil, nitrogen adsorption test was conducted on modified expansive soil to analyze the change of pore structure of expansive soil. The results showed that the BET specific surface area changed linearly with the increase of ash content, and the minimum value was obtained when the ash content was 6%. The cumulative volume of mesopores decreased with the increase of ash content ; With the increase of ash content, the mesopore diameter first increased and then decreased, and reached the maximum at 6% ash content. The water absorption of expansive soil is inversely related to the change of pore diameter of expansive soil, and the optimum amount of ash in expansive soil is 6%.