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Abstract
Fiber-Reinforced Concrete (FRC) results from the addition of short discrete
fibers to the cement-based matrix. Due to the superior performance characteristics of this category of high performance concrete (HPC), its use by the construction industry has significantly increased in the last two decades. Therefore, an extended
comprehensive knowledge of the undamental properties of high performance Fiber-Reinforced Concrete (HPFRC) is necessary. The mechanical properties are among those fundamental properties.
In this study, the mechanical properties of hybrid fiber reinforced concrete (HyFRC) were studied. Twenty four different concrete mixes were used: Portland cement concrete, single type of short fiber reinforced concrete incorporating steel,
glass, and polypropylene with volume fractions (V;-) of 0.8% , 0.8% and 0.4%
,respectively, and HyFRC incorporating steel-glass, steel-polypropylene, glass-
polypropylene, and steel-glass-polypropylene fibers with volume fractions (VI) of
0.8% , 0.6% , 0.6% and 0.8% ,respectively. Their mix constituents were dolomite as
a coarse aggregate with 14 mm maximum aggregate size and siliceous sand as fine aggregate mixed together with a ratio of 1: 1.675. The cementitious material consisted of 350 Kg/rrr’ ordinary Portland cement (OPC), 450 Kg/nr’ (OPC) and 450
Kg/m3 (OPC)with 45Kg/m3 silica fume. The water/cement ratio (w/c) was 0.29.
This led to three concrete grades of 36, 44 and 53 MPa compressive strength
respectively. The steel fibers were 25 mm in length and in the form of twin filament
fibers. The glass fibers were alkaline resistant and 25 mm in length. The synthetic
polypropylene fibers were 15 mm in length. Cube specimens 100xlOOxlOO mm
were prepared to be tested under static compression test. Cylinder specimens of 100
mm diameter and 200 mm height were prepared to be tested under indirect splitting
tension test. On the other hand, prism specimens with cross section of 100x100 mm,
total length of 500 mm, and span length of 400 mm were cast to be tested under the