Performance And Dissolution Characteristics Of Modified C-S Double Liquid Grouting Material

Based on the current concept of green transportation and sustainable development,tunnel construction puts forward higher requirements for environmental protection.The water-rich tunnel has abundant groundwater,so cement-water glass（C-S）double liquid grouting material is often used for waterproofing and plugging construction.During the construction of grouting and after the formation of the stone body,the underground seepage water dissolves the stone body.Current researches mainly focus on the technical properties,mechanical properties,waterproof properties and durability of grouting materials.However,after dissolution,the dissolved species,content,safety and other aspects of diffusion in underground water have not been fully studied.Therefore,the dissolution status of double liquid slurry in underground seepage water and the determination and analysis of the dissolved ions have important reference value for the protection of groundwater and the impact of the construction of the road on the environment.The protection of the road and the impact of the construction on the environment have important reference value.This paper mainly studies the groundwater dissolution of C-S double-liquid grouting materials.As the main raw materials are cement and sodium silicate,the products after reaction are alkaline products such as calcium silicate hydrate,Ca（OH）₂and calcium aluminate hydrate,the p H value of underground seepage water rises,which may be accompanied by the diffusion of Na⁺,Ca²⁺,SO₄^2-and Si O₃^2-.Cause the impact on the underground water body.To this end,a simulated dissolution test will be carried out to test the p H value of the dissolved water sample of the stone body of C-S double liquid grouting material.In addition,the dissolution water sample will be mainly tested for these four types of ions.Furthermore,hexagonal boron nitride nanomaterials were used to modify the grouting materials to reduce the influence of traditional C-S double-liquid grouting materials in groundwater environment and surrounding ecological environment.According to relevant literature and field investigation,collected water velocity and other relevant data,designed and built a set of simulated seepage water dissolution test equipment in water-rich tunnel,and carried out research on the traditional C-S double liquid slurry dissolution,and then adopted hexagonal boron nitride nanomaterials to modify the traditional C-S double liquid slurry.Finally,through sampling analysis,The environmental protection of modified C-S double liquid grouting material was evaluated by comparing the apparent characteristics of dissolved water sample,p H value and the change trend of main dissolved ion concentration.The main research results of this paper are as follows:（1）h-BNNSs was prepared by ball milling method.In order to simulate the dispersion performance of H-BNNSS in slurry,saturated Ca（OH）₂solution was selected,and OP-10 was selected as the dispersant through the dispersion test.The optimal dosage of the dispersant was determined by UV-visible spectrophotometry as 30%.（2）The test shows that the dosage of h-BNNSs,the water-cement ratio W/C,the volume ratio of C-S grout and the dosage of retarder Na₂HPO₄all have an effect on the gel time of grouting materials,among which the dosage of retarder Na₂HPO₄and the dosage of modified h-BNNSs are more significant.In terms of fluidity,with the increase of W/C,the decrease of the volume ratio of C-S grout,the increase of disodium hydrogen phosphate and the increase of h-BNNSs,the fluidity of C-S double-liquid grouting materials increased.In terms of water dissolution rate,it is directly proportional to W/C,the dosage of retarder and the dosage of nanomaterials.With the increase of W/C,the stone rate will also increase.With the decrease of the volume ratio of C-S serous fluid,the stone rate also decreased slowly,but the effect was not obvious.Similarly,the dosage of retarder has little effect on the stone rate.When adding 0.02%retarder,the stone rate can reach 100%.（3）The optimal ratio was determined by orthogonal test as follows:W/C 0.8,C-S slurry volume ratio 1:1,retarder Na₂HPO₄content 3%and h-BNNSs content 0.06%.（4）Through the leaching ion test,the main leaching ions of modified C-S double liquid grouting material are less than those of traditional C-S double liquid grouting material.In particular,the concentration of calcium ion and sulfate ion changed significantly.The experimental study of the paper shows that the modified C-S double slurry grouting material is modified by hexagonal boron nitride h-BNNSs,and the modified double slurry has better compacty and better resistance to main leaching ions,which is helpful to reduce the influence of grouting construction of water-rich tunnel on the surrounding water body and ecological environment,and meets the requirements of green construction and sustainable development.