Study On Road Performance Of Modified Saline Soil With Polypropylene Fiber And Cement-rice Husk Ash

The western part of Jilin province is the largest carbonate saline soil distribution area in China,the soil in this area also has a certain degree of engineering properties of eolian sand soil.With the rapid development of the region's economy and road network improvement needs,more and more highways are under construction or have been built in this area.The improvement of saline soil in the area has become an urgent task.However,the engineering diseases such as expansion,high brittleness,water swelling of the modified saline soil produced by the traditional reinforcement method of adding cement in saline soil with a certain proportion limit the mechanical properties and road performance of the modified saline soil on a certain degree.In view of the disadvantages of the traditional improvement method and considering the composition characteristics of the saline soil in this area,a new reinforcement method of adding rice husk ash,cement and polypropylene fiber into the saline soil was put forward in this paper,and main works are as follow:The research status of saline soil reinforcement was systematically summarized and the properties of raw materials were experimentally analyzed;Three factors and three levels orthogonal test were designed with the contents of rice husk ash,cement and polypropylene fiber as variables;the mechanical properties and road performance of the modified saline soil were systematically studied on the basis of the optimum mixture ratio,and the reinforcement mechanism of the modified saline soil was analyzed by XRD test.Through the above work,the main conclusions are as follows:?1?The addition of polypropylene fiber and rice husk ash can greatly improve the mechanical properties and road performance of saline soil strengthened by cement.Both fiber-cement reinforced saline soil and rice husk-fiber-cement reinforced saline soil meet the requirements of unconfined compressive strength,cleavage strength,CBR and resilience modulus of all grades of highway subbase.?2?Adding rice husk ash can improve the mechanical properties and road performance of saline soil strengthened by fiber and cement.The mechanism isSiO₂in rice husk ash inhibits the chemical reaction between cement hydrate and chloride ions and sulfate ions in saline soil,and reduces the generation of low-strength Friedel's salt and ettringite and calcium silicate which lead to salt expansion.?3?The solidification scheme of rice husk ash 20%+cement 10%+polypropylene fiber 0.3%is recommended to solidify the carbonate subgrade soil in western Jilin province.The research results of this paper can be applied to the treatment of highway subgrade and disease prevention in the saline soil distribution area in the west of Jilin province,and can also provide technical reference for the treatment of highway foundation in other saline soil areas.