Abstract: Carbonation is one of the strength enhanced mechanism for lime stabilized soil. But there has many major problems need solution. For example, whether the long-term carbonation is always beneficial to its strength? If limed soil were not compacted tightly, how about was the carbonated effect of it? So, California bearing ratio CBR tests were performed to evaluated the influence of compacted degree on carbonated effect by preparation samples under curing before and after compacted conditional. And also, CBR tests were carried out to prove the long-term carbonation effect on the strength of lime stabilized soil by analyzing the strength variation of four kinds of initial water contents compacted specimens which were under immersion in carbonate solution and pure water separately. The results show that the CBR values of sample compacted after natural curing 90 days are significantly lower the strength of samples which compacted before curing, when their initial moisture content is 34.0%; the former CBR are about 12 times as the later ones. And, the CBR of samples immersion in carbonic acid solution 15 days are less than pure water immersion ones. But, the higher initial water content is, the smaller the influence is. For example, the initial moisture content is greater than 34.0%, the CBR values are obviously difference between them. In addition, it carried out unconfined compressive strength test under different soaking times, the results further evidence that long-term carbonation can reduce the strength of stabilized soil. Finally, thermo-gravimetric analysis tests are performed to the limed soil to determine the content of calcium carbonate and to evaluate whether or not there are degradation and migration after soaking in carbonate solution. And, it reveals the effect mechanism of different compactions and curing methods on the strength of lime stabilization by scanning electron microscopy photographs and pore size distribution curves.

Key words: lime stabilized soil, carbonated effect, long-term effect, laterite soil