Mineralogical and Microstructural Characterization of Cement-Stabilized Soft Soils Based on Quantitative Analyses

Abstract

The effects of cement dosage (percentage by dry soil weight) and initial moisture content (wo) on cement stabilized soft estuarine clay were investigated by effective integration of multi-quantitative analyses, including quantitative X-ray diffraction (XRD), thermalgravimetric analysis (TGA), Brunauer-Emmett-Teller (BET) test and scanning electron microscopy (SEM) with image processing. These quantitative analyses are highly complementary, which greatly improved the scientificalness of this research. The results revealed that the strength development of cement stabilized soft estuarine clay with varying cement dosages, and initial moisture content was ascribed to the combined influence of both soil fabric improvement and cementation bonding enhancement. The increase of wo resulted in larger clay particle spaces, which can counteract the enhancement of soil structure due to the rising hydration products. The hydration degrees of samples with fixed cement dosage but different wo are quite similar, while clay particle spaces were enlarged with an increase of initial moisture content. Thus, the same quantity of hydration products may bind more soil particles when pores are small at lower wo, thus increasing unconfined compressive strength (UCS). Furthermore, BET and quantitative SEM results illustrate that hydration degree plays a dominant role in the development of intra-aggregate pores (<0.2 μm), while wo affects inter-aggregate pores (0.2 μm–2 μm) more.