Flexural performance of rubberized fiber-reinforced concrete beams incorporating macro synthetic fibers

This paper investigates the flexural performance of rubberized fiber-reinforced concrete (RuFRC) beams incorporating macro synthetic fibers made of recycled plastics and waste tyre rubber shreds to replace coarse aggregates partially. The effects of different percentages of fiber dosages 0 %, 0.25 %, 0.5 % and 1 % on the flexural performance of RuFRC beams are examined. Furthermore, the effects of replacing different percentages of tyre rubber shreds (10 %, 20 % and 30 %) by volume of sand components for any specific fiber dosage are also examined. This paper examines the combined effects of rubber and macro-synthetic fibers on the structural performance and crack pattern in RuFRC beams. The effects of the systematic increment for fiber content from 0 % to 1 % with 0.25 % increment and the changes of rubber content from 10 % to 30 % for each fiber dosage on the structural performance of RuFRC beams have not been well reported in the literature. The novelty of this work lies in investigating how rubber-induced micro-cracking and fiber crack-bridging mechanisms interact synergistically to enhance the strength and ductility of RuFRC beams. Results show that an optimum combination of RuFRC beams with 20 % rubber replacement with 0.5 % fiber content significantly improves ductility and crack control while maintaining acceptable strength levels. It was found that the RuFRC beams exhibited a ductile failure mode similar to the control beam. The maximum reduction of the ultimate failure load was only 19 % compared to the control beam. The toughness of RuFRC beams generally improved with the increase of the rubber percentage yet is lower than that of the control beam. The addition of fibers, particularly at a 0.25 % dosage, further enhanced the toughness of the beam. Ductility increased with higher rubber content, with the highest ductility observed at 20 % rubber within the group of any specific fiber dosage. Fiber dosage also positively influenced ductility, with 1 % fiber showing better performance than 0.75 % fiber. In addition, the design model for predicting the flexural performance of RuFRC beams is examined.