Laboratory experiments were carried out to investigate the aggregation effect of lime dosage and age on two types of expansive soils treated with slaked lime. It was found that the treating effects are rather different for the expansive soils of different liquid-plastic limit. The treating effects on highly expansive soils are much greater than those on the weak expansive soils. The treating effects are mainly completed within the first 24 hour period. As such
the resting time period after the second mixing is suggested to be reduced in engineering practices
which is very beneficial for soil density and strength improvement.