Abstract：Weak and medium expansive soils are widely distributed in the area of the Huanghuai Plain，China. The soil must be stabilized when it is used as the filling of the expressway embankment to improve its strength and reduce its expansion and shrinkage. The two-stage lime adding method，the suitable mixing process and the combination of rolling machine are the key aspects for the construction of lime-stabilized soil. The test results show that the two-stage lime adding method is good for soil pulverizing and compacting. The California bearing ratio(CBR) of stabilized soil is very high although the CBR of the compacted natural soil is such low that it could not satisfy the requirement of the construction code. The free expansive ratio and the expansion of the stabilized soil are very low. The microstructure of the stabilized soil has significant difference to the natural soil. The connection of the particles of stabilized soil is strong and single particles almost could not be found in the stabilized soil.
