Testing of a modified low-mobility grout material for permeation grouting in embankment dams

Embankment dams can be damaged by internal erosion, which ultimately leads to a failure. When internal erosion occurs, finer soil particles from the core soil are washed out. To restore the function of the core, injection grouting can be undertaken. Grouting the core of an embankment dam should be performed with a grout material with characteristics similar to the core soil, such as a low-mobility grout. This type of grout material has similarities to a fine-grained moraine core soil given its stiffness, but it has difficulties permeating the damaged core soil. A modified low-mobility grout material containing gravel, sand, limestone filler, bentonite, plasticizer, air release agent, and water has been tested in the laboratory with focus on permeation. Injection was done on different-sized aggregates. The impact of paste-to-aggregate ratio, grout consistency, maximum grain size of grout material, particle size distribution of injected material, and injection method was tested. Higher paste-to-aggregate ratios, lower viscosity and lower yield strength of the grout material improved the permeation.