Lab-scale study of ultrafine cement grout curtains using a physical model

Curtain grouting is a construction technique by which a continuous grout wall is formed from a series of cylindrical columns placed adjacent to one another. Grout curtains are typically used in permeable soil or rock masses to decrease seepage. Grout curtains are vital to dam and other earthen impoundment restoration projects. In particular cement grouts, such as ultrafine grout, have proven to be very effective in reducing seepage through these impoundments. While the primary purpose of curtain grouting is for seepage control, mechanical behavior of the grouted mass such as excessive settlement and lateral movement is also of concern. In this study, an apparatus and methodology for a lab-scale physical model of curtain grouting was developed. Various measures of mechanical behavior related to grout curtain field practices were investigated. These measures included cure time and interface strength between the soil and grout. In addition, the grout-soil interface strength was a minimum of 66% more than the sand-sand interface strength. This study showed that a lab-scale grout curtain can be adequately implemented to evaluate grout curtain behavior. Finally, this research showed that utilizing a lab-scale physical model of a grout curtain is a valid approach for investigating field-scale grout curtain effectiveness.