One of the key problems must be solved during the construction of the Ninghuai Expressway is how to use the modified expansive soils to construct the embankment. There are three main problems that should be solved for the proper use of the modified expansive soils: the first is how to mix lime into soil homogenously and how to detect lime contents; the second is how to compact the lime-modified soils effectively and what is the proper optimum Proctor density; the last is whether the characteristics of the filling of lime- modified soils is with satisfied the design requirement. Field tests have been conducted to require these questions. The results of the field tests show that the lime-modified soil has low swelling rate

low compression

and high strength if there is reasonable construction method and suitable quality controlled system.