Considering two effects of hydration time and temperature

the swelling deformation and strength characteristics of expansive soil are studied through the laboratory test. The results show that the swelling process of expansive soil after saturation could even still continue for quite a long time

which makes the strength of saturated soil gradually reduced with the extended hydration time. Moreover

during the swelling process of expansive soil

the higher the hydration temperature is

the greater the swelling rate and ultimate swelling ratio are

which results in the strength of saturated soil gradually decreasing with the increasing of hydration temperature. Therefore

the shear strength parameters of saturated expansive soil should consider the effects of hydration time and temperature; and a more suitable formula for expressing the variable shear strength is proposed.