The Research On The Stability Of Freeze-thaw Of Super Wet Soil Treated With Quicklime Tests

After the quicklime is mixed into the subgrade of wet soil,the intermixing of wet and dry materials,the hydration of quicklime and the evaporation of moisture from the mixing process will reduce the moisture content of the soil.However,when the roadbed is formed,its external humidity increases,causing its internal water content to increase.After undergoing a freeze-thaw cycle again,it will cause some damage to the roadbed,changing the original plasticity,swelling and water absorption,and destroying its strength,stability and durability,thereby reducing the project quality and service life.In this paper,we studied the physics,mechanics,and indicators of the soil treated with quicklime in order to treat the lime-slurry roadbed in Jilin Province.The following results were obtained:(1)Quick lime treatment of wet earth liquid plastic limit,the proportion of value with the increase of dosage of lime on the rise,maximum dry density,optimum water content increases,the amount of adding in lime is 5~8% range change is small,the lime soil physical and chemical reaction to generate new "colloid granule".In the same condition,with the increase of the time of the soaking time,the change in the first five days was smaller.(2)With the increase of lime content,the shear strength of lime-treated over-wet soil increased significantly,and the rate of increase in the range of 3 to 5% of ash content was relatively slow.After the ash content exceeded 5%,the strength increased significantly.Considering the physical and mechanical indicators comprehensively,the best ash content of this soil sample is 5%.(3)Comprehensive analysis of the law of change in shear strength and compaction at increasing water content with plain soil and the best ash content results in the conclusion that the test piece cannot be formed whether the plain soil or the lime soil is increased by 4 percentage points.Through freeze-thaw cycles,it was found that the more freeze-thaw cycles,the lower the shear strength;the greater the moisture content,the worse the antifreeze effect.The less the freezing and thawing times of the same conditions,and the closer the water content in the soil is to the optimum moisture content,the better the shear strength effect.(4)Comparing the shear strength test before and after the freeze-thaw cycle at the quicklime treatment soil,it was found that the shear strength after the health effect was better,and the strength after the health decreased linearly with the increase of freeze-thaw cycles,but the intensity of the unrest decreased first,and then rise(peaked 3 to 4 times),and finally fell to a steady state trend,indicating that the strength increased rapidly before the 4th day of health.It was concluded that even if the duration is tight,the time for lime to cure soil should not be less than 4 days.At the same time,it was found that the shear strength of the freeze-thaw cycles stabilized after 7 to 9 freeze-thaw cycles.(5)According to the "EDTA titration method",when the same ash content is used,the lime soil reaction uniformity is better as the ash content increases.After several times of ashing scheme test,it is the best to choose "secondary" ash-blending scheme.Based on comprehensive analysis of strength,reaction uniformity and economic performance,the optimal water content of treated lime at the increase of 2% is the optimum upper limit of water content for construction.At the same time,the CBR freeze-thaw cycle test verifies that the "secondary" ash-blending scheme has the best homogeneity,and the CBR value tends to be stable after 9 freeze-thaw cycles.