Study On The Chemical Corrosion Mechanical Properties And Mechanism Of Gangue-carbide Slag Geopolyme

The Nansha region is adjacent to the South China Sea and has abundant silty clay soil layers.Cement materials are often used to reinforce the silty clay soil foundation.However,a large number of foundation structures are subjected to erosion and attack from chemical ions such as Cl^-,SO₄^2-,H⁺,and Mg²⁺from the ocean,industrial wastewater,and acid rain,ultimately resulting in structural erosion,cracking,and even failure.Introducing green and environmentally friendly,chemically corrosion-resistant geopolymer materials to replace cement mortar has become one of the current research hotspots.However,there is currently limited research on the chemical corrosion resistance and durability of coal gangue-electrolytic slag geopolymer materials.Based on the above problems,this paper simulates the actual mechanical degradation process of geopolymer mortar materials and solidified soil samples with different liquid-to-solid ratios of coal gangue-electrolytic slag geopolymer mortar and immersed in salt solutions of different types and fixed concentrations to simulate the harsh chemical environment encountered by soil reinforcement.Meanwhile,ordinary Portland cement mortar with a water-to-cement ratio of 0.5 and geopolymer mortar with a liquid-to-solid ratio of 0.5 were selected for comparative experiments.Through microscopic experiments,the internal reaction mechanism of the sample under chemical ion erosion was explored,which has certain guiding significance for the promotion of coal gangue-electrolytic slag binary system geopolymer cementitious materials and the practical engineering application of solidifying soft soil foundation.The specific research contents and results are as follows:（1）By observing the changes in appearance,quality loss,and strength loss of mortar specimens soaked in different salt solutions for 12 months,the chemical corrosion resistance of coal gangue-electrolytic slag polymer mortar materials was characterized.The test results show that in sodium sulfate solution and sodium chloride solution,the chemical corrosion resistance of geopolymer materials is better than that of cement mortar,and the appearance of geopolymer specimens remains basically unchanged,and the strength is improved compared with before soaking.However,in sulfuric acid solution and magnesium sulfate solution,the chemical corrosion resistance of geopolymer mortar is worse than that of cement mortar.Among them,in magnesium sulfate solution,geopolymer specimens appeared to collapse after soaking for 3 months,while in sulfuric acid solution,the strength of specimens continued to decrease in the first 6 months and was completely lost at the 12th month.（2）The chemical corrosion resistance of geopolymer mortar specimens with different water-cement ratios was analyzed by fully immersing them in salt solutions of the same concentration.The results show that reducing the water-cement ratio can improve the chemical corrosion resistance of the specimens.After soaking in sulfuric acid solution for 6months,the compressive strength of geopolymer mortar specimens with water-cement ratios of 0.45,0.5,0.55,and 0.6 were 35.94 MPa,24.01 MPa,8.75 MPa,and 5.03 MPa,respectively,and low water-cement ratio specimens showed better chemical corrosion resistance.At the same time,geopolymer specimens soaked in other salt solutions also showed the same mechanical attenuation law.（3）Microscopic experiments were conducted on geopolymer mortar materials after soaking in salt solution,including a series of X-ray powder diffraction,Fourier transform infrared spectroscopy,thermogravimetric curve analysis,mercury porosity distribution pattern,and scanning electron microscopy experiments.The results showed that chemical ions first attacked the surface area of the sample,and penetrated into the core area of the sample through cracks,further attacking the sample.At the same time,there are significant differences in the mechanism of erosion of different types of chemical ions in the geopolymer mortar sample in salt solution.The ranking of the erosion ability of chemical ions on the coal gangue-electrolytic slag geopolymer sample is:Mg²⁺>H⁺>Cl^->SO₄^2-.（4）Based on the experiment of solidifying soft soil with geopolymer under the condition of full immersion in salt solution,coal gangue-electric slag geopolymer mortar with a water-cement ratio of 0.5 was selected to explore its mechanical properties and degradation damage.Under the conditions of an initial water content of 1.00LL,a geopolymer content of 20%,and a fixed confining pressure of 200k Pa,a small triaxial consolidation undrained test was carried out.The results show that the peak deviatoric stress of the solidified soil sample increased significantly in the early stage of immersion in salt solution,but as the immersion time increased,the peak deviatoric stress of the solidified soil sample gradually decreased.At the same time,the erosion effect of chemical ions in salt solution on solidified soil samples caused the phenomenon of strain softening and brittle failure characteristics to become more prominent.