Effect Of Incorporation Of Red Mud On Properties Of Cemented Soil

In order to solve the problem of stockpiling red mud,that is a kind of industrial waste,this paper mainly used red mud as a new soil hardening agent to solidify the loess,so the problem of polluting environment can be solved and the purpose of recycling industrial waste can be achieved.To achieve this research,the major technical indicators of unconfined compressive strength,permeability coefficient and resistivity were tested by unconfined compressive strength test,penetration test,and resistivity test.Those technical indicators were used to analyze the solidification mechanism and curing effect of red mud as solidifying agent.In this thesis,different amounts of red mud and the same amount of cement were selected to solidify the loess.And the resistivity of cemented soil was measured under the condition of different current frequency.The influence of red mud on the microstructure of cemented soil was analyzed by the resistivity of cemented soil.At the same time,unconfined compressive strength tests were carried out on cemented soil.The effects of incorporation of red mud on the strength of cemented soil were analyzed by the change of unconfined compressive strength.The relationship between the incorporation of red mudand the unconfined compressive strength of solidified soil were put forward.In addition,the permeability coefficient of cemented soil was measured under the condition of different osmotic pressure.The influence of red mud on the permeability coefficient of cemented soil was analyzed by the change of permeability coefficient.The relationship between resistivity,unconfined compressive strength and permeability coefficient were established to reflect the curing process and curing effect of red mud and to confirm the possibility of red mud as a soil curing agent.After a series of systematic analysis,the final results show that:(1)With the increase of current frequency,the resistivity of cemented soil decreases rapidly and then gradually becomes stable.When the current frequency is higher than 50 kHz,the effect of current frequency on resistivity is relatively small.The current frequency range should be selected from 50 kHz to1 MHz.(2)With the increase of the incorporation of red mud,the resistivity of immediately molding cemented soil firstly increases,and then decreases.The resistivity of cemented soil after standing shows a decreasing trend.Different molding times can change the relationship between resistivity of cemented soil and the incorporation of red mud.In general,the incorporation of red mud would decrease the resistivity of cemented soil,but the curing effect of red mud on the loess can weaken this trend.(3)When the incorporation of red mud is few,the resistivity of cemented soil increase gradually with the increase of curing time,however,when the amount of red mud is numerous,the conductive ions attached to the red mud will directly dominate the resistivity of the cemented soil,so that the resistivity of the cemented soil are no longer changed obviously with the curing age.(4)With the increase of incorporation of red mud,the unconfined compressive strength of cemented soil gradually increased,and then decreased gradually after reaching the peak.When cemented soil at different molding times achieves the peak of unconfined compressive strength,the incorporation of red mud is different.(5)With the increase of curing time,the unconfined compressive strength of cemented soil increase gradually.And the growth rate of unconfined compressive strength of cemented soil at the early stage is much higher than the later stage.(6)The incorporation of red mud will greatly reduce the permeability coefficient of cemented soil.However,with the amount of red mud increase,the permeability coefficient of cemented soil no longer reduced.Especially,when the amount of red mud is more than 20 g and less than or equal to 30 g,the permeability coefficient of cemented soil will increase.(7)The permeability coefficient of cemented soil(7 d)increases with the osmotic pressure,and then decrease.When the osmotic pressure was more than100 kPa and less than or equal to 150 kPa,the permeability coefficient ofcemented soil(7 d)reaches the maximum.When the curing age was longer than7 days,the permeability coefficient of cemented soil increases with the increase of osmotic pressure,and the change was not obvious.(8)The relationship between cemented soil resistivity and its unconfined compressive strength was linear relationship,and the permeability coefficient and resistivity of the cemented soil were positively correlated.When the resistivity increases,the corresponding permeability coefficient increases.When the resistivity decreases,the corresponding permeability coefficient also decreases.(9)Through the analysis of the test results,it is proved that red mud can be used as a powdery soil curing agent.The strength of the immediately forming cemented soil meet the strength of the basement of the road,and the permeability coefficient also is higher than the requirements of road ditch impermeability.