Experimental Research On Comprehensive Utilization Of Lime And Expanded Polystyrene Beads To Improve Expansive Soil

Expansive soil is widely distributed,and its expansibility does great harm to the project,which is easy to lead to slope damage,deep overall landslide,deformation and destruction of the project body,road damage and other engineering disasters,causing economic losses of tens of billions of yuan every year.On the other hand,with the development of packaging industry and express industry,a large number of waste polystyrene(EPS)are produced,and China alone has 1.8 million tons of waste polystyrene every year.In this paper,EPS beads and lime are used to improve the expansive soil,and the improvement effect of expansion and shrinkage and the mechanical properties of the improved expansive soil are measured by laboratory tests,and the technical parameters are optimized.The main conclusions of this paper are as follows:(1)When the lime content was 4%,the improvement benefit was the best,and the expansion rate did not decrease obviously when the lime content was increased.Among the samples with 4% lime,the moisture content of the sample with the lowest free expansion rate is 21.04%.(2)With the increase of EPS beads content,the free expansion rate decreases linearly,and the no-load expansion rate,load expansion rate and expansion force decrease nonlinearly.The addition of lime and EPS beads can reduce the shrinkage coefficient of expansive soil.Incorporating 4% lime and 15% EPS beads,the shrinkage coefficient are 56% of that of plain expansive soil.This shows that lime and EPS beads have a better effect on reducing the shrinkage of expansive soil.When the content of EPS beads are 5%,the improvement benefit is the best,and then increasing the content of EPS beads does not significantly improve the effect of improving the expansion performance.(3)4% lime can improve the cohesion,unconfined compressive strength,shear strength,compression modulus and other mechanical indexes,in which the unconfined compressive strength is increased by 1.46 times and the shear strength is increased by 2.92 times compared with the plain soil.The unconfined compressive strength,shear strength,cohesion,porosity ratio and compression modulus decrease with the increase of EPS beads.The above results show that the combination of lime and EPS beads as the improvement material is reasonable,and the effectiveness of using this material to improve the expansive soil,which provides a theoretical guidance for the application of the combination of lime and EPS beads to improve the expansive soil in engineering.