The water structures (hydro techniques) dames, reservoirs, barrages ..etc., are complicated engineering structures and may have the demand properties not only hardness and stability but also have the most important property as impermeability [1]. The construction of water structures is highly expensive because they are critical structures and have many purposes. The grand barrages on the Nile are the most important for their many benefits (either in irrigation or industrial …etc). Continuous tests are needed to keep them long time working in effective condition with high efficiency in addition, to repair and strengthen every components. The concrete is the mainly material of the most water structures body and may be subjected to corrosion abrasion and the effect forst may be destroyed by physico-chemical mechanism such as carbonation and phenomena of alkali-aggregate reactions. All of these different modes of deterioration can cause debonding between cement and gravel by the propagation of cracks and loss of material properties [11, 12]. This study concerns with the experimental investigation of injection of barrage body. The main purpose refers to piers completely full of the voids and cracks inside the body material [1], where the cracks are not available to be seen. The disappeared cracks need special operation to get the main characters to perform the suitable operation, in field by the specific discharge, and grout mixing performance should be known to determine the suitable mixing. In the field which the samples of piers are taken (samples are used in this research), the mixing is from ordinary cement with percentage from bentonite (1-2%) from cement weight [1]. The diameter of the core samples which be taken from pier body is (38, 44, 48, 52, 64, 76 and 84 mms.) and after preparing with ratio between the length to the diameter varied from 1 to 2. A 42 samples from Assiut barrage and 43 samples from Naga-Hammadi barrage were taken to perform the required tests [2, 3, 4]. The main objectives of this research are to study the effect of injection to improve the compressive strength and impermeability of the pier body and comparing the results before and after the injection operation [1]. The study concluded that the injection influenced by clear effect on compressive strength. The average compressive strength was increased by (112.63%) from the average strength before injection for Assiut barrage and increased by (81.75%) before injection for Naga-Hammadi barrage. Also the density was improved, to increase the structure solidity and stability.