Climatic effects and road subgrade stabilization

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Studying and validating novel techniques for road subgrade stabilization is becoming an increasingly important field, especially considering extreme climatic effects that may take a toll on road infrastructure. At the same time, initiatives such as Canada's Climate Lens encourages infrastructure projects to maintain a focus on reducing greenhouse gas emissions. The proposed research addresses these issues, while aiming to develop a novel calcium bentontite-based chemical additive for road subgrade stabilization that minimizes, or sequesters, carbon emissions, and remains resilient to the effects of climate change. Two important parameters, the resilient modulus (MR), and the soil suction (s), play a key role in contributing to the stiffness and strength of soils. Ideally, chemical additives, such as a proposed optimum ratio of an alkaline activator and magnesium chloride (MgCl2), lead to higher soil stiffness. Climate change, however, results in a gradual loss of this stiffness. Consequently, the resilient modulus and soil suction parameters must be studied at various temperatures and curing periods to study the strength of subgrade soils, and to predict the climatic influence on stiffness. These behaviours will be studied through a series of spectroscopic and microscopic tests; including: X-ray diffraction (XRD), Energy Dispersive Spectroscopy (EDS), a field emission scanning electron microscope (FESEM), and Fourier transform infrared spectroscopy (FTIR). Additionally, a CO2 sequestration technique of the proposed binders will be studied by carbonating two binders: (i) alkaline activated MgCl2 and (ii) Ca-bentonite alkaline activated MgCl2. The mechanical and microstructural properties of these carbonated binder-stabilized soils will be analyzed through spectroscopic and microscopic tests. The research outcomes of the chemical stabilization technologies will support road construction with materials that have reduced carbon emissions and energy consumption. Moreover, this research will save millions of dollars in long-term public infrastructure projects by developing a greater knowledge of stiffness properties of subgrades under the influence of climate change. Trained HQP exposed to this research will become highly skilled leaders and engineers supporting Canadian innovation in road construction technology.