Abstract: Conventional soil stabilization methods usually involve the addition of some agents or chemicals into soils to generate a composite soil mass with high strength. However, the application of these soil stabilization methods, in general, requires a very long curing time; and it is particularly not economical. By focusing on three typical local soils in Hong Kong, namely, marine clay, completely decomposed granite (CDG), and completely decomposed tuff (CDT), an experimental study of soil improvement is presented, with the use of an innovative and practical bio-enzyme-based soil stabilization technology. As suggested by the experimental results, the stabilization effect of bio-enzyme on marine clay is the best, and unconfined compressive strength of marine clay is able to increase by as high as 20%; while the improvement effect on CDG soils seems not to be quite good since shear strength indices have merely slightly changed after bio-enzyme treatment. It is to be especially noted that the compressibility of marine clay and CDT is improved after treatment, instead of being reduced. Furthermore, the fundamental mechanisms of the bio-enzyme-based soil stabilization are clarified from a microscopic perspective. It is pointed out that the stabilization effect mainly results from the bonding effect generated by the interaction between clay mineral molecules in soils and bio-enzyme molecules.

Key words: bio-enzyme, soil stabilization technology, shear strength, compression index, micromechanism