SYNTHESIS OF ORGANIC-INORGANIC COMPOSITE CURING AGENT AND ITS SOLIDIFICATION EFFECT ON HEAVY METAL CONTAMINATED DREDGED SILT
Dredged silt has the characteristics of high moisture content and low strength,resulting in the inability to be applied directly as an engineering material.It can also pose risk to the environment.In this study,an organic-inorganic composite curing agent was developed,consisting of a synthetic copolymer of acrylic acid and styrenesulphonic acid(AA-SSS),cement,and nano-hydrated calcium silicate(early strength agent).The effect of organic-inorganic composite curing agents on the compressive strength of substrate curing and stabilization of heavy metal ions was investigated and the mechanism was analyzed.The results showed that the organic-inorganic composite curing agent was effective in enhancing the strength of the cured substrate.With the addition of 10％cement,1％AA-SSS,and 2％early strength agent,the compressive strength of the substrate cured for 1 day was 0.85 MPa,increased by 467％compared to that without the addition of curing agent.Under these conditions,the leaching concentrations of Pb2+,Ni2+,Cd2+,and Cr3+in the sediment decreased from 7.05,8.32,4.40 and 7.12 mg/L to 2.68,2.61,0.68 and 2.05 mg/L,respectively.The concentrations of heavy metals in the acid leachate of the solidified and stabilized substrate were all below the hazardous waste identification standard values.The cement hydration products enhance the cementation between the silt particles and encapsulate the immobilized metal ions,while AA-SSS and nano-hydrated calcium silicate disperse and promote cement hydration and immobilize the metal ions by electrostatic action and adsorption.The results show that the organic-inorganic composite curing agent has great potential to improve the compressive strength of silt and the stabilization of heavy metal ions.
heavy metalscontaminated sedimentcuring agentunconfined compression strengthstabilization
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