| Because red clay has special engineering characteristics such as high water content,high plasticity and high void ratio,its plasticity index,liquid limit and CBR value can not meet the technical requirements of high-grade roads for roadbed filling,and need to be modified.Waste tires have light weight,good thermal insulation and water permeability.Foreign research on the use of used tires has started early and has achieved many results.However,there are few studies on the use in the roadbed,especially the modified clay soil needs further research.The paper takes the red clay in Huaxi District of Guiyang as the research object,and systematically studies the effects of different particle sizes and different rubber contents on the liquid,plastic limit and compaction characteristics of red clay through laboratory tests and theoretical analysis.The CBR characteristics of rubber red clay,the shear strength characteristics of rubber red clay under dry and wet cycles and the expansion law of cracks.The road performance of rubber red clay is clarified,revealing the improvement effect of rubber powder on red clay.The main findings are as follows:（1）The liquid limit and plasticity index of red clay slowly decrease with the increase of rubber powder content,and the plastic limit increases slowly with the increase of rubber powder content.The relationship between the maximum dry density,the optimum moisture content and the rubber content of rubber red clay accords with the quadratic parabolic formulay（28）Ax2（10）Bx（10）CA,B,C are Test parameter.（2）The expansion amount of rubber red clay increases with the increase of compaction degree,decreases with the increase of water content,decreases slowly with the increase of rubber powder content,and increases with the increase of rubber powder particle size.The CBR value increases with the increase of compaction degree.It increases first and then decreases with the increase of water content and gets the maximum at the optimum water content.The smaller the particle size of the rubber powder,the smaller the CBR value.As the rubber powder content increases,the CBR value decreases.（3）The cohesive force c of the rubber red clay increases with the increase of the compaction degree,and decreases slowly with the increase of the rubber content,and increases with the increase of the rubber particle size.The internal friction angleφincreases with the increase of the compaction degree,and decreases slightly with the increase of the rubber content,and increases slightly with the increase of the rubber particle size.（4）The cohesion c and the internal friction angleφdecrease with the increase of the number of dry and wet cycles,the first and second dry and wet cycles have larger attenuation,and the third,fourth and fifth attenuations are smaller..The internal friction angle decreases with the increase of the number of dry and wet cycles,and the attenuation amplitude is not as good as the attenuation of the cohesion.（5）As the number of dry and wet cycles increases,the number,width and length of surface cracks in the rubber red clay sample increase.As the number of dry and wet cycles increases,the fracture density increases.The first and second wet and dry cycles have a great influence on the fracture density,and the third,fourth and fifth dry and wet cycles have little effect on the fracture density.The fracture density decreases as the degree of compaction increases,and increases as the rubber content increases.（6）Under the dry-wet cycle conditions,the fracture density is polynomial with the cohesion and internal friction angles,which is consistent with the quadratic parabolic formula.y（28）Ax2（10）Bx（10）C,A,B,C are Test parameter.The greater the degree of compaction,the higher the degree of curve fit and the better the correlation.The cohesion correlation is better than the internal friction angle.In general,Red clay liquid limit,plasticity index,cohesion,internal friction angle and CBR value are reduced after adding rubber powder.The effect of rubber powder on the performance improvement of red clay road is not obvious.The research results provide a certain reference for red clay improvement technology. |
