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

Abstract

Embankment dams can be damaged by internal erosion, which ultimately leads to 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 those of 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, plasticiser, an air-release agent and water was tested in the laboratory with focus on permeation. Injection was done on differently sized aggregates. The impact of the paste-to-aggregate ratio, grout consistency, the maximum grain size of the grout material, the particle size distribution of the injected material and the injection method was tested. Higher paste-to-aggregate ratios, lower viscosity and lower yield strength of the grout material improved the permeation.