Shrinkageis inherent to expansive soil

usually resulting in slope and foundationcracking

but there is little understanding about the influence of structure onshrinkage characteristics. Using an automatic shrinkage test device

comparisontests on shrinkage and scanning electron microscope (SEM) tests for undisturbedand remolded expansive soil were carried out under the same humidity andconstant temperature. The results show that compared with undisturbed soil

remolded soil has smaller evaporation rate in the water flow stage

slowershrinkage stability rate in the vapor evaporation stage and larger volumeshrinkage strain in the end. For the remolded soil

the linear section of thecurve of volume shrinkage versus water content is longer

the slope larger

andthe transition between the linear section and the stable section not obvious

while the undisturbed soil is on the contrary. The soil shrinkagecharacteristic curves (SSC) of remolded and undisturbed soil basically coincidein the section at higher water content; with the decrease of water content

theSSC of remolded soil decreases faster and the corresponding water content rangeis wider

and when entering the residual-zero shrinkage stage

the void ratiois obviously smaller. Chertkov shrinkage model is suitable for undisturbedexpansive soil

but not for remolded one. SEM test results show that theundisturbed expansive soil has stronger primary structure than remoldedexpansive soil. Under the same initial density and humidity

there existsobvious differences in microstructure

such as particle arrangement

contactmode

cementation state

pore size and distribution characteristics between theundisturbed and remolded expansive soil

resulting in smaller water migrationrate and larger matrix suction of remolded soil during evaporation

which isthe internal reason why remolded soil shrinks more violently than undisturbedsoil. The research results can provide a reference basis for the design ofslope engineering protection for expansive soil slopes.