疏浚底泥固化改性与资源化利用技术

通过疏浚底泥固化改性使其作为路基回填土得以安全处置与资源化利用。复配CaO、Al2O3、聚合氯化铝(PAC)、CaSO4制备CAS型和MCAS型固化剂,当聚丙烯酰胺(PAM)、MCAS3/1/4(CaO、PAC、CaSO4复配摩尔比3:1:4)投加量分别占含水率90%底泥湿重的0.2%、1%时,室温养护7 d后,固化底泥无侧限抗压强度达209.56 kPa,液限小于50%,塑性指数为15.67,HJ/T299标准方法测定重金属浸出浓度低于《地表水环境质量标准》(GB3838-2002)Ⅱ类水体相关限值,符合路基回填用土性能要求。X射线衍射分析结果表明,MCAS固化剂固化底泥中有单硫型/多硫型铝酸三钙晶体3CaO·Al2O3·xCaSO4·xH2O生成,这种非水溶性晶体是促进固化底泥体系力学强度形成的关键影响因素。

Study on solidification/stabilization and reuse of dredged sediments

In order to reuse dredged sediments as road filling materials,CaO,Al2O3 aluminiumpolychlorid(PAC) and CaSO4 were screened and mixed to prepare CAS/MCAS solidifier.When the dosages of MCAS3/1/4(the compound ratio of CaO,PAC and CaSO4 is 3:1:4) and polyacrylamide(PAM) were 1 wt% and 0.2 wt%,respectively,the unconfined compressive strength of solidified sediment was 209.56 kPa,liquid limit was lower than 50%,and the plastic index of it was 15.67.According to the standard method of leaching,HJ/T299-2007,the leachable heavy metals of solidified dredged sediments were lower than the legal limits of level Ⅱ(GB3838-2002).It shows that solidified sediment meets with road filling material product standards.XRD indicated that 3CaO·Al2O3·xCaSO4·xH2O was generated in the dredged sediments solidified by MCAS and this kind of crystal is the key factor on the strength development of solidified dredged sediments.