The applications of modern materials especially reactive powder concrete for improving concrete structures have been significantly growing in recent years. Great conduct properties creep, shrinkage, little permeability, ultra-high strength, and expanded safety against corrosion are the important features of Reactive Powder Concrete. In addition, the use of the Near-Surface Mounted technique in recent decades has helped strengthen and repair shears-reinforced concrete (RC) for deep beams using carbon fiber replacement reinforcing bars. The parameters studied in the present research investigated the impact of the maximum load, deflection, stress–strain curve of concrete, first shear crack, crack pattern, and crack width. Considering the aforesaid cause and objective, one specimen of Reactive Powder Concrete RC deep beams has a rectangular cross-section of 150 mm in width, 500 mm in depth, and a total length of 1.2 m. One control specimen was tested for comparison. In addition, 12 control specimens (cylinder and cubes) are used for experimental investigation on the mechanical properties of normal and Reactive Powder Concrete deep beams. Following the specimens’ processing, they were subjected to one concentrated load pressure test through a hydraulic jack. Moreover, six core drill specimens were taken from those deep beams to obtain the real mechanical properties of those beams, including maximum stress, modulus of elasticity, density, stress–strain curve, and Poisson’s ratio, after subjecting them to the pressure machine. Depending on the results, the ultimate strength, deflection, and first shear crack capacity for the specimens (RPCDB1P-4NSM & RPCDB1P-8NSM) have increased by (21, 25), (47, 27), and (133, 150)%, respectively, compared with (CDB1PC20). Moreover, the specimens above have reduced the first shear crack width by (9, 33.25)% respectively compared with (CDB1PC20) at 65% of the ultimate shear load.