الفهرس 
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Abstract
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 Poly Propylene 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 4.0%)) in concrete mixture design. Hardened concrete properties, 28-days tensile strength, flexural strength, cracking width were evaluated. Then the mortars are subjected to the following temperatures 50 °C, 100 °C, and 200 °C. The temperatures were selected based on the results of thermal analyses tests carried out to investigate the thermal degradation of the PP fiber. The mechanical properties were investigated flexural strength, deflection and
tensile strength of the cement mortars Statistically significant effects were observed for polypropylene fibers on the 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. The tensile and flexural specimens exhibited the multi-crack and strain-hardening behavior up to 100 °C, while a brittle failure occurred at 200°C due to the melting of fibers. The microstructures of temperature ECC specimen were determined by the scanning electron microscope (SEM) and Energy-dispersive X-ray EDX data. The SEM results show that the thermal effect was detrimental to the fiber morphology, while the EDX results show the significant effect of temperature on the .surface of ECC matrix