Impact of salinity on strength and microstructure of cement-treated Champlain Sea clay

Abstract

An experimental investigation was conducted to understand the impact of salinity on the microstructure, phase composition, and shear strength of cement-treated Champlain Sea clay. Based on a scanning electronic microscopy (SEM) analysis, Champlain Sea clay exhibits an open structure fabric with flocculated particles. Leaching results in de-flocculation of the aggregates and leads to an increase in inter-aggregate porosity in the clay. Cement mixing transforms a dispersed microstructure into a flocculated state with a large amount of clay-binder aggregates. Cementitious products were formed and reduced both inter-aggregate porosity and intra-aggregate porosity in the cement-treated clay specimens. Sodium chloride salt has a negative effect on the strength development of cement-treated Champlain Sea clay. Under the same cement dosage of 50 kg/m3, the unconfined compressive strength of cement-treated leached clay samples exhibited higher shear strength values than those at natural or a higher salinity level. An optimum salinity level was found to be at 1.33 g/L in this study to achieve the highest shear strength, which was confirmed with the densest microstructure in the SEM and a series of stronger and wider cementitious peaks of cementitious products in the X-ray diffraction analysis.