Normal concrete has long met the needs of construction industry; however, the need to build high-rise, stronger, and smaller structural elements led the researchers to obtain higher strength concrete. Studies conducted by researchers led to the appearance of new type of concrete with extraordinary properties within the last two decades. Such concrete with compressive strength of greater than 100 MPa is known as Ultra-High Performance Concrete (UHPC). In this study, glass fibers (volume percent of 1.5 and 2.2) are employed to increase some mechanical properties of UHPC. Using glass fibers improves the concrete properties including increased tensile strength, increased flexural strength, increased impact resistance, increased energy absorption capacity, improved concrete behavior in non-linear area, and increased ductility. Since the properties of glass-fiber reinforced concrete is directly associated with glass fibers used in concrete surface, subjects related to the performance of glass fibers have always been the subject of interest for researchers. Some factors change the mechanical properties of glass-fiber reinforced concrete including alkaline environment of concrete and cement products manufactured by the hydration process over time along with the destruction of glass fiber. In this study, metakaolin and silica fume pozzolans are employed to reduce the destructive effects on glass fibers over the time. Three methods were employed to study the effect of curing on UHPC. Wet curing was tested as control, while curing with autoclave was tested in order to study the effect of heat and pressure on properties of concrete reinforced by glass fibers. Another method was employed to protect the glass fibers by adding acrylic polymer to concrete mortar. Samples were kept at room temperature for curing. The results show that fibers had minor effect on UHPC compressive strength. Autoclave curing has the highest effect on compressive performance of concrete. Curing by acrylic polymer leads to highly reduced compressive strength. Modulus of rupture of concrete increases highly by adding fibers to concrete. Reduction of flexural strength was observable in all samples over time. Curing by acrylic polymer highly slows down reducing flexural strength over time. Toughness indices are very high in samples undergoing acrylic polymer curing. Using glass fibers increases highly the toughness indices. Keywords : Glass-Fiber Reinforced Ultra-High Performance Concrete, Metakaolin, Silica fume, Wet Curing, Autoclave, Acrylic Polymer, Mechanical Properties.
