Abstract: The expansive soils have the tendency to expand in wetting and to shrink in drying. The addition of cement is one of the methods to enhance the engineering properties of such soils. The effects of varying cement contents and curing time on the engineering properties of the expansive soils are investigated through the measurements of free swelling index, Atterberg limits and unconfined compressive strength of weak expansive soils along a section of water diversion project from Yangtze River to Huaihe River. The test results show that increasing the amount of cement decreases the free swelling index, liquid limit and plasticity index, whilst the unconfined compressive strength increases. Also, increasing the curing time leads to a reduction in the free swelling index, liquid limit and plasticity index, but an increase in the unconfined compressive strength. After seven days of curing the measured soil properties begin to be stable. Thus, the improvement of the expansive soils by cement takes long time.