Research On The Durability Of Geopolymer Under The Coupling Effect Of Multi-factor

Geopolymers are prepared from minerals or industrial wastes containing silicon and aluminum.The preparation method is low-carbon and environmentally friendly.It is currently the main research object of domestic and foreign scientific researchers.However,to apply geopolymers to actual projects,it is necessary to consider their performance in complex environments.Environmental factors in engineering applications mainly include acid,alkali,salt corrosion,freeze-thaw damage.Therefore,this paper studies the coupling effects of different types of salt solutions,freeze-thaw cycles,and loads.The ability of geopolymers to adapt to complex engineering environments is to solve Provide a basis for engineering application technical problems.Through the research on the mix ratio of geopolymer cementing materials,the mix ratio of geopolymer used for durability research is selected.The ratio of mineral powder is 7:3,the modulus of water glass is 1,the water-binder ratio is 0.2,and the mortar ratio is It is 1:3.Choose NaCl and Na₂SO₄ as the corrosive medium,the concentration of NaCl solution is 3%,the concentration of Na₂SO₄ solution is 2.5%,5%,and the coupling salt solution is 3%NaCl+2.5%Na₂SO₄ and 3%NaCl+5%Na₂SO₄.Solution dry-wet cycle and freeze-thaw cycle,and then apply 30%,50%,70%of the maximum load to the geopolymer,evaluate the performance of the geopolymer under the coupling effect of multiple factors,and establish the number of salt freezing cycles,mass loss,and relative dynamics.Mathematical model of elastic modulus.Under the corrosion of 3%NaCl solution,the quality,compressive strength and flexural strength of the geopolymer have no obvious changes.In the 3%NaCl solution,25 cycles of dry and wet cycles will not cause damage to the geopolymer.;Under the corrosion of 2.5%Na₂SO₄solution and 5%Na₂SO₄ solution,the quality of the geopolymer increases,but the compressive strength and flexural strength are reduced.After 25 wet and dry cycles,the concentration of2.5%and 5%Na₂SO₄ The solution will cause damage to the geopolymer.Under the coupling action of 3%NaCl solution,2.5%Na₂SO₄ solution and 5%Na₂SO₄ solution,respectively,the quality,compressive strength and flexural strength of the geopolymer increased slightly,and 25times of dry and wet cycles in the composite salt solution would not Cause damage to geopolymers.Under the coupling action of 3%NaCl solution and 2.5%Na₂SO₄ solution and 5%Na2SO4 solution respectively,the quality,compressive strength and flexural strength of the geopolymer increased,and the number of small pores from 0 to 100μm decreased,and the number of pores larger than 100μm was not obvious.Change,a small amount of corrosion products were observed.25 dry and wet cycles in the composite salt solution will not cause damage to the geopolymer.Under the action of salt solution corrosion and freeze-thaw cycles,the quality,compressive strength and relative dynamic elastic modulus of geopolymers are greatly reduced.After 25freeze-thaw cycles,the degree of degradation of geopolymers in NaCl solution is the highest,and the composite salt solution The degradation degree of geopolymers in Na₂SO₄ is the second,and the degradation degree of geopolymers in Na₂SO₄ solution is the least.From the analysis of pore structure and relative dynamic elastic modulus,the internal structure of geopolymer deteriorated most seriously under the coupling effect of composite salt solution and freeze-thaw cycle.Under the maximum load of 30%,50%,and 70%of the bending load,the mass and compressive strength of the geopolymer after freezing and thawing in the salt solution are reduced.Among them,the degradation and destruction of geopolymers is the most serious after freeze-thaw cycles in a 3%NaCl solution.After the salt solution and freeze-thaw cycle coupled erosion test,the geopolymer mass loss rate,relative dynamic elastic modulus and the number of freeze-thaw cycles are fitted to obtain a quadratic curve equation,and a good correlation is found.The regression analysis of the compressive strength loss rate of geopolymers and the relative dynamic elastic modulus shows that it is linearly correlated.The strength of geopolymers under the coupling action of salt solution and freeze-thaw cycles can be predicted and analyzed by measuring the dynamic elastic modulus.