碳化条件下电石渣-氧化镁固化淤泥土的试验研究

Experimental Study of Carbide Slag-MgO Stabilized Mud under Carbonation Condition

软土是一种分布广泛的工程性质差的土类,使用水泥对其进行固化处理已不再符合当今社会发展要求。采用电石渣-活性MgO复合固化剂及CO_(2)气体对淤泥质土进行碳化固化处理,设置固化剂掺量(单掺电石渣)及固化剂掺和比(电石渣:MgO)两组变量,从物理力学和化学等方面分析碳化固化土的工程性质。结果表明:(1)当单掺电石渣含量为20%时,碳化土体强度最高;掺入混合固化剂时,碳化后试样强度随电石渣掺入比的升高呈先上升后下降趋势;(2)碳化后试样密度较碳化前有显著增长,单掺电石渣时,碳化后试样密度随电石渣掺量的增加而增加;掺入混合固化剂时,碳化试样密度的变化规律与强度变化一致;(3)碳化土的pH较碳化前有显著下降,单掺电石渣时,碳化土的pH随电石渣掺量的增加而增加,掺入电石渣∶MgO=4∶3的混合固化剂时,碳化土pH明显减小;(4)碳化土样的粗颗粒(>75μm)含量显著提高,碳化土样的粗颗粒比例随固化剂掺量增加而降低,但掺入混合固化剂时,碳化土样的粗颗粒比例与电石渣和MgO比例无显著相关性。研究结果有利于提高电石渣固废的资源化利用,拓展电石渣-MgO碳化固化技术在软土处理中的工程应用。

Soft soil is a kind of widely-distributed soil with poor engineering properties,and its stabilization using cement does not meet the requirements of modern social development.The composite binder of carbide slag-reactive MgO and CO_(2) were used to carbonize and stabilize silty soil,and two variables of the binder dosage(single carbide slag)and the carbide slag-MgO ratio were set.The engineering properties of the carbonated/stabilized soil were analyzed from the physical mechanics and chemistry aspects.The results showed that:①when the content of only carbide slag was 20%,the soil strength was the highest after carbonation.With the addition of a mixing binder,the strength of the carbonated sample increased first and then decreased with increasing the incorporation ratio of carbide slag.②The density of the carbonated samples increased significantly compared with that before carbonation.When calcium carbide slag was only added,the density of the carbonated samples increased with the increasing content of carbide slag.With the addition of a mixed binder,the variation in the density of the carbonated samples was consistent with the strength.③The pH of the carbonated samples decreased significantly compared with that before carbonation.With the addition of carbide slag,the pH increased with the increase of carbide slag content after carbonation.With the addition of a mixing binder,the pH decreased obviously after carbonization when the carbide slag-MgO ratio was 4∶3.④the proportion of coarse particles(>75μm)in the carbonated samples significantly increases,and it decreased with increasing the content of carbide slag.However,there is no significant correlation between the proportion of coarse particles and the carbide slag-MgO ratio when the mixing binder is added.The results would be beneficial to improving the utilization of solid waste resources and expanding the engineering application of carbide slag-MgO carbonation technology in the treatment of soft soils.