Geotechnical Properties of Cement-Treated Champlain Sea Clay-Paper

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The paper reviews laboratory studies on cement-treated Champlain Sea clay, a sensitive marine clay found in eastern Canada. In its natural state, the clay has low shear strength, high water content and compressibility, and can lose strength dramatically when disturbed. These properties contribute to flow-type landslides and long-term settlement, creating challenges for infrastructure construction.<br /><br />Researchers prepared treated samples using wet or dry mixing and tested their strength, stiffness, compressibility, tensile strength, and microstructure. Cement increased unconfined compressive strength (UCS) with dosage and curing time. General-use Portland cement was more effective than lime, and about 100 kg/m³ was identified as a cost-effective dosage; at least 50 kg/m³ was needed for a meaningful strength increase. Strength gain also depended strongly on the total water-to-binder ratio. Cement kiln dust and slag showed potential as partial cement replacements, with strength gains developing over longer curing periods. Dry mixing generally produced higher strength than wet mixing, but with greater variability.<br /><br />Treatment also increased stiffness and reduced compressibility. The compression index fell from about 2.3 for natural clay to roughly 0.4 in the studied treated samples, while yield strength increased. Tensile strength was approximately 6.5% of UCS in Brazilian tests and 4.6% in unconfined penetration tests. Microscopy showed that cement hydration products filled pores and bonded clay particles, forming a stronger soil-cement matrix.<br /><br />Overall, cement mixing substantially improves the strength and compressibility characteristics of Champlain Sea clay and is a promising ground-improvement approach for construction in the region.

Keywords

Champlain Sea clay

cement-treated clay

ground improvement

unconfined compressive strength

wet mixing

dry mixing

compressibility

Portland cement

soil-cement matrix

sensitive marine clay