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In this diplomatic assignment the goal is the examination of the impact of superplasticisers in the effectiveness of cement grouts. This paper is divided into two sections, the theoretical where there is an analysis of basic parameters regarding the subject and the experimental, which describes the process that was followed, as well as the results with their analysis. Hydraulic cement grouts have been extensively used during the last decades for the reinforcement of rock-mass and soil substrates, of underground works such as tunnels, dams and many others. The mixture of these grouts is usually consisted of water and cement with a ratio by weight that varies according to the working conditions and in connection to the condition of soil and rock-mass. It is well known in practice that, when we need to reinforce extensively disintegrated rock-mass and substrates, or to fill big voids of rock-mass (stabilization groutings), we must use hydraulic cement grouts with low water/cement ratio. In order to give efflux and impregnation ability to these grouts, addition of superplasticisers is needed. Superplasticisers are consisted of various systems of organic compounds that include in their chemical structure a hydrophobic part as well as hydrophyllic polar ends. Their hydrophobic part is adsorbed onto cement particles, while their hydrophyllic ends attract water molecules, thus accelerating the hydration and increasing the efflux of the system. The superplasticisers that were used were sulphonated naphthaleneformaldehyde (SNF) and sulphonated ether polycarboxylates (PCE). It was used cement of the type Ι/32.5 Ν, with 20 % content of «Thiraiki Soil», and of high strength. The grouts that were obtained after addition of plasticiserssuperplasticisers had hydrometric coefficient ranging from w/c = 1/2 to 1/3. The properties that were tested, according to Greek Regulation and A.S.T.M., were fluidity, setting time, compressive strength (after 3, 7, 28 days) and shrinkage. Addition of SNF and PCE resulted in the improvement of physical and mechanical properties of the grouts. The experimental part of the diplomatic assignment took place in the labs of the Civil Engineer Department of the Alexander Technological Institute of Thessaloniki. As far as the theoretical part, most of the bibliography was foreign due to the lack of publications in the Greek language in these subjects.