An Engineered Cementitious composite is an ultra ductile cementitious composite which is highly crack resistant, with a tensile strain capacity over that of normal concrete. In this study, three different types of PP. fibers are added to cement mortars with the aim to determine how they can be used to develop ECC materials. Fibers are used in different (aspect ratio, tensile strength and different proportions in volume fraction (1.0, 2.0, 3.0 and 4%)) in concrete mixture design. Hardened concrete properties, 28-days splitting tensile strength, flexural strength, cracking width were evaluated. Statistically significant effects were observed for polypropylene fibers on the splitting tensile and flexural strength, toughness indexes, and durability parameters showed an increase in the presence of polypropylene fibers. Increased fiber availability (fiber aspect ratio) in the concrete matrix, in addition to the ability of longer polypropylene fibers to bridge on the micro cracks, are suggested as the reasons for the enhancement in mechanical properties. Finally, crack width in fiber-reinforced concrete is calculated analytically with fiber property variables (fiber type, length, diameter and proportion). Results are compared with experimental values and concluded that with an increase in fiber length and/or decrease in fiber diameter crack width, decrease significantly