To explore the improvement effect of adding silt onexpansive soil

the swelling-shrinkage characteristics

road performance andmicrostructure of expansive soil with different proportions of silt weretested. The results show that the incorporation of silt changes the compositionand structure of soil particles

and inhibits the expansion and contraction potentialof expansive soil. With the increase of silt particles

the compactness andunconfined compressive strength of expansive soil increase first and thendecrease. The maximum dry density reaches 1.889 g/cm when theproportion of silt is 40%

and the unconfined compressive strength reaches themaximum when the proportion of silt is 10%. The California bearing ratio (CBR)value continues to increase significantly

and the rebound modulus shows a downwardtrend. All of these indexes meet the requirements of the specification. Thefeasibility of using silt to improve expansive soil is verified

and theoptimum dosingratio of silt is determined to be 40%. In order to facilitate onsiteconstruction and consider the uniformity of onsite mixing

3% low-dosage limeis first added to causes the performance of expansive soil to tend towardsthose of sandy soil so as to reduce the viscosity of the expansive soil andbreak it. On this basis

the expansive soil is applied to highway embankmentfilling after improved with 40% silt content

and onsite compaction degree

CBRvalue

deflection and other tests are carried out. The field test results showthat the overall compaction quality of the experimental section improved bysilt and lime and the control section treated by the single lime are controlledwell

but the compaction degree of the test section is reduced due to the influence of theuniformity of the silt. The CBR value and subgrade deflection of the testsection are comparable to those of the control section

and the siltimprovement effectively compensates for the strength provided by the 2% limereduced relative to the control section.