reconnaissance and appraisal of effective parameters on washout of cementitious grout in dam foundation

Grouting materials being washed away by groundwater flow is one of the difficulties with cement injections, which may cause water to be wasted, the foundation to weaken, and eventually dam failure. the flow of water in the rock mass, depending on the ratio of retention, the composition of the cementitious compound, the amount of pressure, water velocity, and the geological structure of the dam foundation, may cause washout and transport of grouting materials. in this project, laboratory studies of different mixtures with different compositions have been performed. the experiments were conducted in two forms, a standard funnel and three types of porous media with different permeability and the ability to apply different water pressures. it was found that the lower the water to cement weight ratio, the lower the washout grout of the compound. the highest resistance to washout grout by the compound was obtained using sodium bentonite. by increasing the amount of permeability and water pressure inside the media, washout grout of the mixtures also increases, and this increasing trend can be presented by a linear function. moreover, a method has been proposed that can be effectively used to select the suitable initial composition to start the injection operation in environments with water flow.