Microstructure Analyses Of Reinforcement Mechanism Of Cement In Stabilizing Champlain Sea Clay

This research investigates the strength development and the formation of microstructures in Champlain Sea clay when treated with Portland cement and other cement-based binders and the effect of salinity level in the pore fluid on the strength and the mineralogical changes of cement-treated Champlain Sea clay. Champlain Sea clay, a sensitive marine clay commonly found in St. Lawrence Lowlands in eastern Canada, can lose up to 90 % of its strength when disturbed. The unconfined compressive strength tests were used to measure the shear strength development of binder-treated samples. The results indicated that cement-treated clay samples gain the shear strength at a faster rate than other binders under short-term curing conditions up to 28 days.

However, under the same cement dosage of 50 kg/m3, the samples treated with cement with an additional 17 kg/m3 slag and those treated by cement with an additional 50 kg/m3 kiln dust exceeded the performance of those treated with only cement under the 300-day curing condition. Qualitative microstructural and mineralogical characterisations of cement-treated clay samples are investigated using scanning electron microscopy and X-ray diffraction (XRD). The results confirmed the transformation of an open structure in natural clay to a flocculated and aggregated structure due to the development of cement hydration products. The XRD analysis confirmed the formation of hydration products are found to be more pronounced in clay samples with a lower salinity level.