Engineered cementitious composites (ECCs) are new materials that have been developed after years of research to remove one of the biggest defects in concrete, such as brittleness and low ductility. In fact, ECC is a fiber-reinforced cementitious material that has a very high ductility and has been optimized in its design, mixing ratios, and other influential parameters by the theory of micromechanics. A characteristic feature of the ECC is its high ductility with strain-hardening behavior. Unlike conventional concrete that undergoes localized cracking due to tensile stresses, the ECC exhibits multiple cracking under tensile stress, which means that in the area under tensile stress, a large number of cracks with a relatively small gap (less than 2 cm) and small crack width (less than 100 microns) beget. The tensile strain of ECC in direct tensile testing is usually more than 2%. The mechanical and geometric properties of the fiber play a significant role in many of the characteristics of the ECC, including strain-hardening behavior and cracking behavior. The ECC was originally developed with polyethylene fibers (PE), but because of its high cost, PVA fibers were replaced by PVA, which is currently the most commonly used fiber in making ECC PVA fibers. In this thesis, the durability of ECC containing zeolite and microsilica in magnesium sulfate environment is investigated. For this purpose, the mechanical properties and durability of ECC made with PVA fibers and polypropylene (PP) are compared experimentally. In this study, in addition to cement, zeolite, microsilica, and limestone powder were used in production of ECC. Mechanical properties and durability of samples made at the age of 28, 150, 180 and 210 days have been investigated and compared. In order to investigate the mechanical properties of the samples, the compressive strength tests and toughness test were carried out to determine the durability of the samples in the magnesium sulfate medium. The variations in compressive strength, rupture modulus, mid-span deflection and surface area under the load-displacement curve were measured, as well as changes‌‌in mass and volume. It was also observed in this study that ECC manufacturing with pozzolans such as microsilica and zeolite, although not common in previous studies, was feasible, and the samples produced showed a‌ mechanical‌ and‌ durable characteristic. Keywords: Engineering cementitious composite, Zeolite, Microsilica, Polypropylene fibers, Polyvinyl alcohol fibers, Magnesium sulfate environments.