Study On The Blocking Of Underground Pollution Source By Geopolymer Blocking Wall

Leakage of landfill leachate,discharge of three industrial wastes,leakage of underground storage tanks and oil pipelines at gas stations have caused serious groundwater pollution.Groundwater pollution is concealed and difficult to treat,which leads to the high cost of some existing remediation technologies and the unsatisfactory remediation effects.Therefore,it is necessary to develop a cost-effective method to control the spread of pollution sources.As an emerging environmentally friendly material,geopolymers have the advantages of good fluidity,acid and alkali resistance,high strength and low permeability,and low price.Based on this,this research proposes to inject geopolymer materials into the ground to form low permeability around pollution sources The vertical barrier prevents the migration of pollutants and controls the further spread of pollution sources.The paper selects high-territory territory and fly ash as a silicate raw material at a ratio of 4:1,and studies the Influence of setting time and flow of geopolymer slurry,viscosity,and permeability by changing the sodium silicate dosage?Na₂O as the mass percentage of the raw material?,the sodium silicate modulus and the water-raw material ratio.Based on the experimental results,a mixture of good fluidity,low viscosity,low permeability coefficient,and suitable setting time for grouting was selected for subsequent blocking adsorption experiments.The geopolymer was modified by adding nano-alumina The changes in the geopolymer's pan-alkali,strength,adsorption of heavy metals,and microstructure were studied.The specific results are as follows.?1?When the sodium silicate dosage is used as a variable,as the sodium silicate dosage is increased,the setting time is reduced,the viscosity is increased,the fluidity at 5 minutes is slightly increased,and the fluidity at 30 minutes is increased and then decreased,and the permeability coefficient is gradually Decrease.When the sodium silicate modulus is used as a variable,as the sodium silicate modulus increases,the setting time of the geopolymer gradually increases,the fluidity increases,the viscosity decreases,and the permeability coefficient decreases.Among them,the sodium silicate modulus is 0.8.It is difficult to measure the fluidity and viscosity of the sample because the coagulation speed is too fast.When the water-raw material ratio is used as a variable,as the water-raw material ratio increases,the setting time of the geopolymer increases,the fluidity increases,the viscosity decreases,and the permeability coefficient increases.?2?Through studying the setting time,viscosity,fluidity,and permeability coefficient of geopolymers with different proportions,comprehensively analyze four parameters to evaluate the performance of geopolymers,and select No.2,No 3,No.8,and No.10 These four are suitable as the proportion of grouting material.?3?By adding an appropriate amount of nano-Al₂O₃,the pan-alkali performance of high-territory and fly ash composite-based geopolymers can be improved,and the optimal addition amount is 2wt%.Nano-Al₂O₃ can also improve the compressive strength of geopolymers.The compressive strength of the sample first increased rapidly with the increase of nano-Al₂O₃,and then gradually decreased,and this value was the largest when the dose of nano-Al₂O₃ was 2.0 wt%.Nano-Al₂O₃ can enhance the compactness of the geopolymer structure.When the addition amount is 2wt%,the microstructure of the geopolymer is the most dense.The addition amount of nano-Al₂O₃ has no effect on the final Cu²⁺adsorption amount.?4?The geopolymer has good alkali and salt resistance and compatibility with organic pollutants,but when it is immersed in an acidic solution,the surface foams and falls off,indicating that the acidic solution will destroy the geopolymer.The structure caused the layers of geopolymers to decompose.