In a recent experimental program dealing with the Near Surface Mounted (NSM) technique for the flexural strengthening of continuous reinforced concrete (RC) slabs strips, the increase of load carrying and the moment redistribution was lower than the expected values. This experimental program was analysed in depth in this thesis and it was concluded that more efficient flexural strengthening arrangements can be applied if carbon fibre reinforced polymer (CFRP) laminates (of rectangular cross section) are applied not only in the intermediate support (hogging region), but also in the positive bending moment zones (sagging regions). Thus, an experimental and a numerical research program were carried out, and it was verified the possibility of increasing the load carrying capacity in 25% and 50%, maintaining a relatively high level of moment redistribution, when correct NSM flexural strengthening arrangements are used. For assessing the predictive performance of a FEM-based computer program, the experimental tests were simulated by considering the nonlinear relevant aspects of the intervening materials. After has been concluded about the capability of this model to simulate the behaviour of this type of structures, a parametric study was carried out to investigate the influence of the strengthening arrangement and CFRP percentage in terms of load carrying capacity and moment redistribution capacity of continuous RC slab strips flexurally strengthened by the NSM technique. Additionally, to predict the load-deflection response of this type of structures up to its collapse, an analytical model was developed and its performance was appraised by using the data obtained from the experimental program. This model is based on the flexibility method and requires the knowledge of the flexural stiffness of the representative cross sections of the structure, which can be determined from the moment-curvature relationship of these sections. The increase of the load carrying capacity of the strengthened slabs can, however, can be limited by the formation of a shear failure crack in the hogging region. To avoid the occurrence of this brittle failure mode, a new technique, designated Embedded Trough Section (ETS) was developed, and its effectiveness was appraised by testing two series of RC beams of different cross section. Finally, the most relevant conclusions extracted from the present study are presented, and further research developments are suggested.