Abstract: Both physical properties and mineral composition of Guilin red clays are unique. To investigation the effect of the sand and flayash mixing on the Guilin red clay improvement, a series of laboratory tests, such as Atterberg limits, direct shear tests and Proctor tests, were performed on soils mixed with various amounts of sand and flyashes. It is concluded that the optimum sand content is 20% and flyash content is 10%.

Key words: red clay, sand, flyash, soil improvement