Stabilisation of clayey soils with industrial by-products: part A

Hydrated lime, activated fly ash and activated slag have been used to stabilise a number of soils collected from a range of locations across Australia. This paper explores the reaction mechanics of soils and industrial by-products in the role of stabilisation. Scanning electron microscopy and X-ray diffractometry analyses on stabilised soils were carried out after various curing periods. Based on the extensive study of the microstructural and mineralogical developments, it was found that the soil microstructure undergoes dramatic changes during the modification and stabilisation processes. The different stabilising agents were also shown to have influenced the nature and form of developing microstructural elements. The slag particles were subjected to significant surficial transformation, whereas fly ash relied exclusively on through-solution mechanisms, and was comparatively inert under the prevalent conditions. The presence of organic matter in soils was found to interfere with the nucleation and growth of cementitious phases causing slow gain in strength properties. Finally, these results were used to elucidate the development of the geotechnical properties of the stabilised soils in an accompanying paper by the authors (part B).