Influence of Drying-wetting Cycles on Dynamic Characteristics and Microstructure of Geopolymer Solidified Sludge
In order to promote the application of geopolymer solidified sludge in the field of roadbed,the dynamic characteristics of geopolymer solidified sludge under drying-wetting cycle conditions are studied.The fly ash based geopolymer was activated by sodium hydroxide(NaOH)to solidify Guizhou sludge as roadbed filler.The evolution of dynamic stress-strain relationship,failure dynamic stress(σdf),dynamic elastic modulus(Ed)and cumulative plastic strain(εp)of geopolymer solidified sludge under drying-wetting cycle conditions were studied,and the microscopic mechanism was analyzed by scanning electron microscopy(SEM)test.The results show that with the increase of drying-wetting cycles,σdf and Ed of geopolymer solidified sludge show a trend of increasing first and then decreasing,whileεpdecreases first and then increases.Increasing the concentration of NaOH can effectively improve the dynamic characteristics of solidified sludge.The SEM results confirmed that the promoted formation of C(N)-A-S-H gel in the early stage of the cycle to improve the cementation between particles,and the weakening of the structure in the later stage caused the attenuation of the dynamic characteristics.The empirical model of cumulative plastic strain of geopolymer solidified soil under drying-wetting cycles is established,in order to provide reference for similar projects and research.
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