Smectite formation upon lime stabilization of expansive marls

Marl was treated with Mg-rich lime to evaluate the effectiveness of lime stabilization for this expansive, clay- and carbonate-rich material. XRD and TEM analyses revealed very limited dissolution of expandable clay minerals and neoformation of Mg-enriched smectites. C-(A)-S-H phases formed and initially cemented clay particles. However, they experienced decalcification and decomposition over time, leading to disaggregation of clay particles and deterioration of some of the marl's geotechnical properties. Results question the effectiveness of lime stabilization for marls, especially using Mg-rich lime. Modifications to commonly used treatment protocols in order to overcome these shortcomings are discussed.