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ACI Materials Journal


This paper determines the effect of discrete fibers on the elastic modulus of concrete and cement composites. Five types of discrete fibers consisting of steel, polypropylene, macro-polyolefin, polyvinyl alcohol (PVA), and basalt fibers were investigated. Results show that discrete fibers had little effect on elastic modulus for fiber-reinforced concrete (FRC) with coarse-to-fine aggregate ratio (C/S) greater than 1. However, for FRC with C/S smaller than 1 and fiber-reinforced cement composites (FRCCs), discrete fibers reduced the elastic modulus. Accordingly, a new elastic modulus equation is proposed to better estimate the elastic modulus of FRC with a maximum fiber volume fraction of 10%. The proposed equation was compared with existing equations from other codes, including American, Japanese, Korean, Norwegian, and European codes, as well as equations proposed by other researchers. These equations were evaluated using more than 400 data points taken from the experimental program and other literatures. The proposed equation provides the most accurate prediction for the elastic modulus of FRC and FRCC with a coefficient of variation of 15% as compared to 32% using ACI 318 equation for C/S ≤ 1.

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