Evaluation of shear strength characteristics of coarse-grained soils by performing laboratory tests resorts often to a scalping or scalping/replacement procedure due to the presence of oversized particles in comparison with the device size. This work aims to study consequences of these two procedures on the resulting shear strength characteristics. Experimental tests are performed on soils having gap-graded particle size distributions by using triaxial apparatuses with small and medium diameters Φ = 50 and 100 mm. Original soils are mixtures of fine particles (sand and glass beads) and coarse particles (two types of gravel). The original soils are scalped and/or scalped/replaced by two different procedures. Different factors that influence the mechanical properties of the scalped and scalped/replaced soils in comparison with those of the original soils are analyzed: (i) the compactness parameter controlled for scalped and scalped/replaced soils, (ii) the fine content of the original soils and (iii) the procedure used for the scalping/replacement.