Abstract: The loess samples solidified by reactive magnesium oxide (MgO) and microbes are analyzed in this paper. Water content and unconfined compressive strength are measured, and X-ray diffraction (XRD) and scanning electron microscopy (SEM) are conducted on different samples to investigate the curing product and microstructure change with varying amount of reactive MgO, curing time duration, initial water content. The results show that the water content of solidified sample decreases with the increasing content of reactive MgO and the growing curing period. The unconfined compression strength increases with the increasing content of reactive MgO, and also increases with the growing curing period in general, but decreases slightly in the later period with the content of reactive MgO being 10% or 15%. With the increase of initial water content, the unconfined compressive strength of solidified samples decreases when the reactive MgO content is 5% or 10%. But it will first increase and then decrease while the amount of reactive MgO is 15% or 20%. The results of XRD and SEM tests show that the higher the content of reactive MgO, the more magnesium hydroxide remains. The hydrated magnesium carbonate produced by the reaction is swellable and cementitious, which can fill the gaps between the soil particles and cement the soil particles together.

Key words: loess, microbes, reactive magnesium oxide, water content, unconfined compression strength