Research On Engineering Characteristics Of Lime And Fly Ash Stabilized Salt Rock As Pavement Base

As the industrial development in the salt lake area,which puts forward higher requirements for the development of local transportation infrastructure,and the environmental changes have caused more and more salt rock roadbed diseases in the salt lake area.To solve these key issues,the paper proposed that using inorganic binders such as lime and fly ash to improve the mechanical strength and corrosion resistance of salt rock and form the lime-fly ash stabilized salt rock mixture as a pavement base material.In this paper,a constrained uniform formulation design method was used to study the regression relationship between a large range of lime and fly ash content and the 7d unconfined compressive strength(UCS),temperature shrinkage coefficient and dry shrinkage coefficient of the mixture,the results indicate that a proper dosage of lime and fly ash could increase the UCS of salt rock in an acceptable shrinkage performance.Combined with the study of the typical mixture microscopic structure and chemical analysis,it was found that the strength of lime-fly ash stabilized salt rock is mainly derived from the embedded structure and self-healing structure of the salt rock itself and the hydration reaction products of the lime and fly ash,meanwhile,the shrinkage performance of the mixture is related to its pore structure and moisture content,after comprehensively considered the engineering properties and social economic benefits of the mixture,the recommended lime and fly ash dosage of the mixture was decided finally.The paper also conducted a comparative experimental study on the mechanical and shrinkage properties of lime-fly ash stabilized salt rock mixed with aeolian sand,the results showed that aeolian sand has obvious negative effects on the mechanical and shrinkage properties of lime-fly ash stabilized salt rock,which is caused by the fragile connection between the sand and other components in the mixture from the microscopic perspective,as a consequence,the aeolian sand should not be used as a partial replacement of the salt rock in the mixture as the stabilized materials.The dissolution test of remolded salt rock,lime-fly ash stabilized salt rock,and lime-fly ash stabilized salt rock with aeolian sand showed that the lime and fly ash can improve the corrosion resistance of salt rock,and the severity of the mixture’s corrosion is not only related to the mixture itself,but also related to the solution concentration,temperature and time.In generally,the lime-fly ash stabilized salt rock with 8%lime and 32%fly ash without aeolian sand has an excellent performance on UCS,temperature shrinkage,dry shrinkage and anti-corrosion,which is the recommended material in salt lake area.