Issue 54

J. Akbari et alii, Frattura ed Integrità Strutturale, 54 (2020) 116-127; DOI: 10.3221/IGF-ESIS.54.08

lowest value equal to 52%. For both fibers, in 0.3%, the ratios of tensile strength to flexural strength are in the highest value of about 62%. As an approximate estimation, we can say r t f 1.60f  and r c f 0.13f   .

Figure 11: Ratios of tensile strength to flexural strength at the age of 28 days

C ONCLUSIONS

I

n the present paper, the behavior of plain and fiber-reinforced concretes is experimentally studied. The effects of water- to-cement and steel and glass fibers on compressive, tensile, and flexural strengths were investigated. According to the results of this study, the following conclusions could be drawn;  The presence of steel fibers in concrete with 0.3% to 0.9% fraction volume of concrete increases the compressive, tensile, and flexural strengths for both water- to- cement ratios. Glass fibers only increase compressive strength in the range of 0.3% to 0.6% and using more than this value decreases compressive strength. By increasing glass fibers up to 0.9%, tensile and flexural strengths are also increased.  The steel fibers have better performance in comparison with glass fibers in all cases. Therefore, based on the results of this study, the authors suggest that adding steel fiber is preferable than adding glass fiber. If, for any reason, the fibers are not available, the reduction of water-to-cement- ratio is recommended instead of adding fibers to improve the mechanical properties of concrete.  Using concrete containing steel fibers is preferable than glass fibers due to the lack of water absorption and the proper spreading of steel fibers.  The tensile strength and flexural strength of concrete could be approximately explained as 8% and 13% of compressive strength, respectively. In practical applications, for designers t c f 0.08 * f   and r c f 0.13 * f   is recommended

C ONFLICTS OF I NTEREST

T

here is no conflict of interest to declare.

R EFERENCES

[1] ACI Committee 544 (1996), State-of-the-art report on fiber-reinforced concrete, report 544.1R-96 American Concrete Institute, Detroit.

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