Study On Road Performance And Microscopic Mechanism Of Magnesium Oxychloride Cement Stabilized Clayed Soil

Inorganic binder stabilized materials are widely used in highway pavement base and subbase in China because of their advantages of good stability,high cost performance and self-made structure.However,traditional cementitious materials such as Portland cement and lime have high carbon emissions,high energy consumption and non-renewable raw materials in their production process.The shortcomings of non-renewable materials have brought severe challenges to the realization of the current national “carbon peak” and “carbon neutrality” strategic goals.Therefore,it has become a subject with practical application value to introduce green magnesium oxychloride cement into the field of pavement base and subbase,and to explore the feasibility of applying magnesium oxychloride cement stabilized soil to pavement base and subbase.The paper relies on the science and technology research project of Jilin Provincial Department of Education “Research on Road Performance and Micro-mechanism of Modified Magnesium Oxychloride Cement Stabilized Soil”(JJKH20220291KJ).The clayed soil of a road project in Erdao District of Changchun City is used as the stabilized object,and fly ash is used as the modifier.Firstly,on the basis of determining the basic physical properties of raw materials and the range of influencing factors,the three-factor and three-level Box-Behnken Design is carried out according to the response surface methodology.Through heavy compaction test,unconfined compressive strength test and water stability test,the response index value of the design mixture ratio is obtained.The response surface model and fitting equation of compressive strength and softening coefficient were established.The influence of various factors on different response indexes was analyzed,and the optimal mixture ratio of magnesium oxychloride cement stabilized clayed soil was determined.Then,through the unconfined compressive strength test,indirect tensile strength test and compressive rebound modulus test,the variation of the basic mechanical properties such as unconfined compressive strength,indirect tensile strength and compressive rebound modulus of magnesium oxychloride cement stabilized clayed soil with curing age was obtained.Based on the water stability test,freeze-thaw test and temperature shrinkage test,the effects of immersion,freeze-thaw cycle and temperature change on the road performance of magnesium oxychloride cement stabilized clayed soil were studied,and the softening coefficient,water absorption,freeze-thaw cycle compressive strength loss and temperature shrinkage coefficient were obtained.Finally,the microstructure and material composition of magnesium oxychloride cement stabilized clayed soil were studied by scanning electron microscopy and X-ray diffraction,and the microscopic mechanism of its macroscopic performance evolution was discussed.The research results of the paper can provide basis and reference for the application of magnesium oxychloride cement stabilized soil in pavement base and subbase.It has important scientific value and practical significance for promoting the application of new cementitious materials in road engineering,accelerating the promotion of energy conservation and emission reduction in the field of transportation infrastructure construction,and assisting the implementation of the national “double carbon” strategy.