Influence of carbon sequestration in natural clay on engineering properties of cement-lime stabilized soil mortars

Carbon sequestration in natural soil, and using it for manufacturing of stablized earth-based materials can be an effective pathway for low embodied carbon constructions. This research demonstrates a possibility of sequestering carbon dioxide in clayey-soil, comprising of kaolinite and montmorillonite minerals, and examines its influence on rheological properties, hydration, mechanical strength and shrinkage of cement-lime-soil mortars. Carbon sequestration reduces the specific surface area, pore volume and lime reactivity of carbonated soil (CS). This leads to higher availability of unconsumed lime in cement-soil mixes, resulting in faster hydration, higher yield stress and plastic viscosity of cement-lime mixes with CS than control (with natural soil). Higher precipitation of binder gel due to addition of CS result in better stabilization, higher wet strength-to-dry strength ratio and up to 18% lower drying shrinkage than control. Depending on clay content and type of soil (S or CS), 40-58% of drying shrinkage can be reversed.