干湿循环条件下碱渣-钢渣-电石渣固化疏浚淤泥的强度性质

Strength Properties of Dredged Soil Treated with Soda Residue,Steel Slag and Carbide Slag Subjected to Drying-wetting Cycle

为扩展固体废弃物的资源化利用途径,以碱渣和钢渣作为固化剂、电石渣作为激发剂,对高含水率疏浚淤泥固化处理,研究固化淤泥在干湿循环条件下的强度性质。正交试验表明,碱渣对固化淤泥强度的影响随养护龄期的增加而增强,固化污泥养护28 d时,碱渣对强度的影响显著,而钢渣和电石渣对强度的影响不显著。在干湿循环条件下,固化剂掺量较少的试样在第3次浸水时破坏;其他试样经5次干湿循环整体仍完整,1次干湿循环使固化淤泥的强度降低约1/2,后续干湿循环对强度的影响不大;增加固化剂掺量有助于提高固化淤泥的干湿循环耐久性。固化淤泥的水化产物主要有水钙沸石和钙钒石,钙钒石随养护龄期和固化剂掺量的增加而减少。与碱渣-矿渣-电石渣固化淤泥相比,碱渣-钢渣-电石渣固化淤泥中胶结力较强的水化产物偏少,而钙钒石具有膨胀性,使试样端部破损形成薄弱带,故后者的强度较低和干湿循环耐久性较差,但仍能满足对强度要求较低的一般填土工程的需要。

In order to expand resource utilization of solid waste,dredged soil at high water content was stabilized with soda residue(SR),steel slag(SS),and carbide slag(CS).Unconfined compressive tests of stabilized soil subjected to drying-wetting cycle were conducted.The influence of SR on strength increases gradually with the increase in curing time,based on orthogonal test analysis.After the sample being cured for 28 days,the influence of SR on strength is significant and the influences of SS and CS are insignificant.During drying-wetting cycle tests,the sample with lower stabilizer content is destroyed in the third immersion,while the others are almost intact after 5 cycles except some defects and looseness at the ends.The strength of stabilized soil after 1 cycle is only half of the value before cycle,and the subsequent cycles have little effect on strength.Increase of stabilizer content improves dry-wet durability of stabilized soil.Hydration products in stabilized soil include gismondine and ettringite,and the latter decreases with the increase of curing time and stabilizer content.Lack of hydration products with strong cementation,expansibility of ettringite,and weak zone from the defects at the ends of the specimen contribute to worse drying-wetting durability of soil stabilized with steel slag than that stabilized with blast furnace slag.Nevertheless,SR-SS-CS solidified dredged soil can meet the needs of fill engineering with low strength requirements.