The effects of non-traditional additives on the geotechnical properties of tropical soils have been the subject of investigation in recent years. This study investigates the strength development and micro-structural characteristics of tropical residual soil stabilized with magnesium chloride (MgCl2) solution. Unconfined compression strength (UCS) and standard direct shear tests were used to assess the strength and shear properties of the stabilized soil. In addition, the micro-structural characteristics of untreated and stabilized soil were discussed using various spectroscopic and microscopic techniques such as X-ray diffractometry (XRD), energy-dispersive X-ray spectrometry (EDAX), field emission scanning electron microscopy (FESEM), Fourier transform infrared spectroscopy (FTIR) and Brunauer, Emmett and Teller (BET) surface area analysis. From the engineering point of view, the results indicated that the strength of MgCl2-stabilized soil improved noticeably. The degree of improvement was approximately two times stronger than natural soil after a 7-day curing period. The results also concluded the use of 5 % of MgCl2 by dry weight of soil as the optimum amount for stabilization of the selected soil. In addition, the micro-structural study revealed that the stabilization process modified the porous network of the soil. The pores of the soils had been filled by the newly formed crystalline compounds known as magnesium aluminate hydrate (M-A-H).Ministry of Education Malaysia under the Fundamental Research Grant (FRGS) (R.J130000.7822.4F658); Universiti Teknologi Malaysia (UTM); Construction Research Centre UT
