EXPERIMENTAL STUDY ON LIME AND ITS ADDITIONAL AGENT TO CURE TIANJIN MARINE SOFT SOIL

The mechanical behavior of Tianjin marine soft soil can't meet the requirement of engineering construction, but it can be enhanced effectively by curing agents. Moreover when curing agents and additional agent are added in the soft soil together, the strength of the stabilized soil can be improved further. For this reason, the method of combing lime and cement or gypsum is proposed in this paper. In the test the unconfined compressive strength of solidified soil is used as a criterion to identify the solidifying effect. Meanwhile, sample microstructure is analyzed with SEM and the unconfined compressive strength of destroyed and re-cured samples is measured and recorded. Test and analysis results indicate that the optimum content of cement only changes with the different dosage of lime. For example, if the content of cement in stabilized soil adding 12% lime is less than 3%,the effect of solidification is the best. Gypsum can't improve the soil strength. It even makes the water stability of soil badly and causes the soil crack under the influence of water. Although the compressibility of both lime stabilized soil with and without additional agent is low, their various mechanical properties can be improved obviously. Their failure mode is the brittle failure. The strength of destroyed soil is very low and can't recovery, to which attention should be given in practice. Microstructure analysis shows that the C-S-H(hydrated calcium silicate),acicular ettringite, CaCO3 and Ca(OH)2 crystal formed in soil can fill pores and cement particles. Effective and proper product is beneficial to improve the strength of stabilized soil. The total of pores and particles in solidified soil increases with the augment of the pressure, however, area of pore, equivalent diameter of both pores and particles decreases with the augment of pressure.