Experimental Research on the Influence of Polypropylene Macrofiber Thickness in Fiber-Reinforced Concrete Mechanical Strengths

Herein, the effects of polypropylene fiber thickness on the compressive strength, split tensile strength, and flexural strength or modulus of rupture of polypropylene fiber reinforced concrete (PPFRC) were investigated. In consequence, knurled straight polypropylene fibers with three different thicknesses of 0.75, 0.90, and 1.05 mm and a constant length of 50 mm were used in conjunction with three fiber weight dosages of 4.00, 5.00, and 6.00 kg/m³ and four water-cement ratios of 0.40, 0.45, 0.50 and 0.55. In total, forty different concrete mixes were prepared with four control samples. The mechanical behavior of PPFRC as a function of polypropylene fiber thickness was determined in conjunction with its fresh-state properties. The results showed a strong indirect proportional correlation between fiber thickness and compressive strength of PPFRC for mixtures with water-cement ratios of 0.45 and 0.50. On the other hand, there is no statistically significant correlation between the split tensile strength and the modulus of rupture with fiber thickness.