Therefore, it is relevant to investigate the behavior of the model's micro-parameters for the constitutive contact model to better understand the mechanisms associated with reproducing the material experimental behavior. The calibration of micro-parameters of numerical models is a key process for the generation of accurate predictions. Recent efforts have been developed to clarify a methodology for the assignment of micro-parameters to cemented/rock materials [16; 17; 18; 19; 20]. Nonetheless, micro-parameters are not the only factor influencing the DEM's mechanical behavior. [PERSON] and [PERSON] [14] demonstrated that the DEM's Young's Modulus has a clear dependence on the particle size (PS) of the a La du granite PFC3D model. [PERSON] [21] concluded that PS influences the sample's ultimate stress and peak strain at a particular model PS-model size ratio. [PERSON] et al. [22] concluded that the UCS and Young's Modulus decrease with a wider Gaussian normal PS distribution (D\({}_{max}\)-D\({}_{min}\)), where D is the particle diameter. The aggregate shape considered in the model affects the model results; however, a simplified approach considering circular and spherical particle shapes in 2 Dand 3D DEMs, respectively, can lead to results in good agreement with the experimental observations [23; 24]. The uniform and the Gaussian normal distribution are the more commonly used PSD models (PSD) in the DEM [22]. However, studies with non-uniform PSD have concluded that particle shape, sample packing, and PS affect the compressive strength, tensile strength, and strain localization of DEMs [25; 26]. Furthermore, computational time represents a limitation in DEM simulations when attempting to reproduce the experimental PSD of the specimen, forcing researchers to up-scale or simplify the sample's geometry. This practice can lead to the DEM's inaccurate behavior [27]. Masonry components have been widely studied. Their physical and mechanical properties have been even characterized over time. Cement, sand, and lime are the main constituents of mortar. C270-19a ASTM [28] recognizes four different types of cement-line mortars. Each one contains different proportions of cement, sand and lime, which results in different compressive strength, permeability and workability. Mortar is chosen to be investigated in this paper since it is one of the two main components of masonry systems. C109/C109M-20 ASTM [29] presents the testing methodology for compressive strength testing of hydraulic cemented mortars. The standard suggests 2 in (5 cm) cube specimens. Nonetheless, [PERSON] et al. [30] tested mortar cylinders of 15 cm diameter and 30 cm height under compressive strength. The purpose of this methodology was to produce a much finer stress-strain curve response of the material. Studies related to mortar have been found in the literature where they use DEMs to characterize its mechanical properties [31; 32; 33]. Nonetheless, limited research is available on the influence of micro-parameters and PSD on the masonry components using DEM modeling. Moreover, the study of masonry as a system and its components using a micro-modeling methodology has not been further investigated [34]. In this research study, a mortar cylinder is modeled using a 2D-DEM utilizing PFC-2D software V.5.0 [35]. Models of a mortar cylinder under compressive strength test were developed. A calibration procedure throughout an optimization process was applied to determine the micro-parameters of the DEM. The models were calibrated using previous experimental tests conducted at the Autonomous University of Yucatan (Mexico) [24]. The contact model considered for the DEM is flat-joint. This research study is divided into three analyses. Three PS and one PSD are considered in the first analysis. This is set to identify the influence of the PS on the mechanical behavior of the model and the variations of the micro-parameter's values. One PS and four PSDs are considered in the second analysis.