Investigation On The Performance And Microscopic Characteristics Of Complex Cementitious-sodium Silicate Two-shot Grouting Materials

Traditional cement-sodium silicate two-shot grouting material was widelyapplied to strengthening and plugging in underground watery strata due to itsadvantages of shot gel time and high early compressive strength.However,its structurestability and anti-corrosion of groundwater is poor owing to erosion damage of watercomposed of acids,salts and other substances. Based on the traditional cement-sodiumsilicate two-shot grouting material and comprehensive using industrial waste(flyash,slag),this paper presents a new cmmplex cementitious-sodium silicate two-shotgrouting material. Besides, the performance and micro-properties of grouting materialis investigated.According to the short gel time of cement-sodium silicate and alkali-activatedsalic cementitious material, The liquid A was produced by cement combined with flyash,slag,and mixed with sodium silicate, formed complex cementitious-sodiumsilicate two-shot grouting material.The main research results are listed as follows:(1) The influence of factors such as dosage of sodium bentonite and naphthalenesuperplasticizer, modulus and dosage of sodium silicate,power proportion on workperformance and gelling properties was systematically studied. The results showed:grout has good stability and fluidity when the dosage of sodium bentonite andnaphthalene superplasticizer are3%,1%. Its gel time can be adjusted between severaldozens seconds and several minutes by changing the dosage and modulus of sodiumsilicate,powder proportion.The compressive strength of stone body is the largest whenthe dosage of sodium silicate is controlled in20%. Increasing modulus of sodiumsilicate or cement,fly ash,slag which are mixed can improve the compressive strengthof stone body.(2) The anti-chemical corrosion of complex cementitious-sodium silicatetwo-shot grouting material is better than that of traditional cement-sodium silicatetwo-shot grouting material through analyzing the strength loss under the condition ofacidic medium, carbonates,sulfates corrosion.(3)The microstructure of grout were researched by XRD,SEM microscopic testing methods. The results showed: after adding fly ash,slag, Ca(OH)2content ofliquid product in complex cementitious-sodium silicate two-shot grouting materialdecreases. During early hydration, the microstructure becomes loosend. As thehadened age increases, the microstructure is improved significantly and becomesgradually dense. Compared with standard curing condition, under the condition ofcorrosion curing, Ca(OH)2content in traditional cement-sodium silicate two-shotgrouting material is reduced significantly, and the microstructure becomes loosend,but the Ca(OH)2content of complex cementitious-sodium silicate two-shot groutingmaterial changes small, and the microstructure is still dense.