Microstructural Analyses of a Stabilized Sand by a Deep-Mixing Method

The deep-mixing method (DMM) involves the mechanical mixing of in-situ soil with various stabilizing binders, which chemically react with the soil or the groundwater. Microstructural analyses are valuable tools to support ordinary geotechnical laboratory tests to assess the effectiveness of ground improvement works. This paper presents the results of microstructural analyses on in-situ retrieved samples and laboratory mixed specimens related to an actual deep mixing job site. Mercury porosimetry and X-ray computed Microtomography were used to determine the total porosity and to characterize the pore network of both types of samples. The results of the analyses allowed a qualitative understanding of the degree of mixing of the soil with the binder suspension under laboratory and field conditions. Additionally, an original correlation between total porosity and unconfined compressive strength was obtained based on the experimental data for cement-treated sandy soils at long curing time.