Experimental study on ex-situ S/S for shallow soil of organically contaminated site

4 kinds of binders are utilized to remedy the organically contaminated soil. The effects of curing age and binder type on physico-mechanical and environmental safety properties of the stabilized soils as well as the remediation efficiencies and mechanisms are studied by analyzing the results of ex-situ S/S and laboratory tests, such as unconfined compression strength tests and toxicity characteristic leaching procedure. The results show that with the increasing age, pH of soil and organic concentrations of leachate decrease while the dry densities and q_u increase steadily. The dry densities of soil remedied by binders No. 3 and No. 4 are higher than those by other binders and over 1.38 g/cm³ after 28 days. The pH values of soil greatly increase with the addition of binders and are the highest for binder No. 4 (calcium carbide residue + attapulgite). 4 kinds of binders have different remediation effects on organic contaminants owing to different organic types, and they all have high removal efficiencies for aniline, 2-chlorophenol, naphthalene, benzene, methylbenzene and o-Xylene. In point of the overall effectiveness, activated carbon-based binder No. 1 is the best because its total removal efficiency approaches 93%. The q_u of soils stabilized by cement-based binders No. 2 and No. 3 is higher than that of other binders and over 109 kPa after 28 days. Binder No. 4 is optimum for the re-use of organically contaminated soil because of its low cost, low energy consumption, low pollutant emission, high q_u and total removal efficiency.