AbstractThe 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.Practical ApplicationsConstruction of buildings and infrastructure on marginal ground is becoming more common due to rapid urbanization and population growth. These phenomena has led to the utilization and development of coastal and estuarine plains surrounded by relatively softer and weaker soils that require improvement or strengthening before being constructed upon. One such ground improvement method is termed deep soil mixing (DSM), which involves mixing cement with the in situ weak soils to increase the soil strength so that the ground can sustain the weight of the buildings or infrastructure. This manuscript presents a novel interpretation based on the results from advanced laboratory tests to succinctly explain the complex chemical reactions that occur when cement is mixed with soft soils having varying characteristics. It is envisaged that this evidence-based explanation will help engineers and scientists bring to life land that was previously deemed unsuitable for construction.

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