Study On Road Performance And Curing Mechanism Of Caofeidian Saline Dredger Fill Solidified By Mineral Powder Composite Curing Agent

The dredger soil in coastal area is characterized by large water content,large void ratio,small bearing capacity of natural foundation and high salt content.If the foundation of the dredger soil is not handled properly,uneven settlement will occur easily,which will cause great harm to the structure.This paper takes shallow dredger soil in Caofeidian Industrial Park as the research object,analyzes the basic physical and mechanical properties of dredger soil in this area through geotechnical tests,and and clarifies the soil properties of the dredger soil in this region;on this basis,it is proposed to use the mineral powder composite solidified agent to solidify Caofeidian dredger fill,and the optimal ratio of each material of mineral powder composite curing agent was determined by single factor variable method and orthogonal test method;Based on the optimal proportion,the composite solidified agent of mineral powder is obtained.The long-term road performance of the composite solidified agent of mineral powder is studied through the mixing amount test,settlement test,water stability test,dry wet cycle test and freeze-thaw cycle test.Finally,combining the SEM and XRD experiments,we proposed the action mechanism of mineral powder composite curing agent for curing Caofeidian dredger soil.The main conclusions of this paper are as follows:(1)Caofeidian dredger fill has high moisture content,uneven particle grading,and more fine particles.It is silty clay,and the content of soluble salt in the soil is high,which belongs to the saline soil in chlorine.(2)The solidification effect of the mineral powder composite curing agent is remarkable,of which quicklime has the greatest influence on the solidification effect of the mineral powder solidified salted dredger fill,10% mineral powder,1.0% quicklime,0.8% sodium silicate,1.5% Gypsum powder is the optimal ratio of mineral powder composite curing agent.(3)Both the mineral powder composite curing agent and the cement curing agent can improve the sagging of the saline dredger fill;at the same mixing ratio,the initial improvement effect of the mineral powder composite curing agent and the cement curing agent is not much different.With the increase of curing time,the improvement effect of mineral powder composite curing agent is obviously better than cement curing agent.(4)Both the mineral powder composite curing agent and the cement curing agent can improve the water stability of the saline dredger fill;at the same mixing ratio,the cement curing agent has a better initial improvement effect,but as the curing time increases,The improvement effect of mineral powder composite curing agent is obviously better than cement curing agent.(5)The mineral powder composite curing agent has a very good improvement on the dry and wet resistance of the salted dredger fill.Under the same mixing ratio,the mineral powder composite curing agent improves the anti-dry and wet resistance of the salted dredger fill It is better than cement curing agent.(6)The SEM results show that the pore distribution of the dredger soil decreases after the composite powder is solidified,the soil structure is more closely arranged,and the compactness of the dredger soil increases.The mineral powder curing agent greatly improves the space filling capacity of the Caofeidian dredger soil.(7)The curing mechanism of the mineral powder composite curing agent can be divided into a three-stage curing process.During the primary curing process,the mineral powder hydrates to form hydrated calcium silicate colloid and hydrated calcium aluminate colloid;the secondary curing process is,Calcium aluminate hydrate is combined with gypsum powder and sulfate ions in saline soil to form ettringite;the threestage solidification process is that calcium hydrate aluminate reacts with Na Cl in the soil to produce hydrated calcium chloroaluminate,hydrated Under the action of sulfate ion,calcium chloroaluminate produces the final product hydrated calcium aluminum chlorosulfate.The research results can provide a certain guidance and theoretical basis for the foundation solidification project in coastal saline dredger area.