Organic-rich soil is a typical special soil often encountered in foundation treatment. Previous research has revealed that Portland cement (PC) not only pollutes the environment but is significantly affected by organic matter during its hydration and cementation. Although quicklime (CaO)-GGBS binder (CG) is an effective alternative to PC, its efficiency in treating organic-rich soils has not been studied. In this study, organic-rich soil was treated with two binders of CG and PC. The physical, mechanical, and chemical characteristics of the stabilized soils were tested at various organic contents, binder contents, and curing ages. The results show that the cracks in two treated soils increase with the increase in organic content and the reduction in binder content. CG-treated soils are more likely to shed big lumps after damage than PC-treated soils. The unconfined compressive strength (qu) and deformation modulus (E50) of stabilized soils increase with the increasing curing age and binder content but the decreasing organic content. The E50 of PC-treated soil is about 22~73 times qu, and the E50 of CG-treated soil shows an excellent linear relationship with qu. The moisture content of two treated soils increases as the organic content grows, but it falls as the curing age and binder content increase. The soil pH rises with the increasing organic content and binder content, but it declines with increased curing age. The strength development of organic-rich soils treated by the CG binder has an evident attenuation with the organic content. Given its possible environmental benefit, alkali (especially low calcium)-activated binder is appropriate for practical engineering with modest strength needs.

The swelling-shrinkage and cracking characteristics of compacted clay under the coupling effect of initial conditions are rarely studied. The dry-wet cycle test of compacted clay with varying initial water contents and densities was performed in this study; the size and cracking conditions were investigated. The results showed that when the initial moisture content was 21% and the dry density was 1.65 g/cm3, the longitudinal expansion amount of the compacted clay was relatively small. However, it was rather large when the initial water content was 17% and 19%. Under the same dry density, the final vertical shrinkage ratio of the sample with a water content of 21% was the smallest, while that of the samples with a water content of 23% and 25% was rather big. Under the same water content, the final vertical shrinkage ratio decreased with the increase in dry density. After three wetting-drying cycles, compacted clay with a dry density of 1.65 g/cm3 and an optimal initial water content of 21% produced the fewest cracks and had the lowest cracking factor (CF) (only 7.58%). The compacted clay specimens with the dry densities of 1.55 g/cm3 and 1.60 g/cm3 had rather significant cracking at the same initial moisture content of 21%. The mercury intrusion porosimetry (MIP) test demonstrated that in the first two dry and wet cycles, the distribution of large pores decreased and that of tiny pores increased. After the third cycle, the distribution of small and medium pores decreased slightly. The results of this study will provide theoretical guidance for selecting cover soils in landfills.

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