Performance characteristics of synthetic hybrid fiber-reinforced roller-compacted concrete pavements

Roller-Compacted Concrete (RCC) pavement, with advantages in cost-effectiveness, mechanical performance, production, and construction, stands out as an alternative to hot-mix asphalt. In RCC pavements, tensile cracks and wear occur due to exposure to heavy traffic loads and environmental effects. The tensile cracks and wear that develop in the early stages of the pavement accelerate rapidly, leading to increased maintenance costs and reducing the expected service quality and lifespan of the pavement. This study aims to develop RCC pavement designs that can provide longer service life by enhancing performance characteristics. To achieve this objective, the effects of hybrid usage concentrations of synthetic macro and microfibers on the performance properties of RCC mixtures were investigated in a laboratory setting. In the experimental study, a single type of aggregate and cement binder was used, with the cement dosage set at 350 kg/m³ across all mix groups. Macro fiber length was chosen as 60 mm, and it was added to the mixture at volume ratios of 0%, 0.20%, 0.40%, 0.60%, and 0.80%. Initially, the optimal macro fiber content yielding the best results was identified, and hybrid mixtures were prepared at this mix ratio. Hybrid mixtures were produced with polypropylene microfiber additions at 0.05%, 0.10%, and 0.20% by volume. The optimum water content of the mixtures was determined according to TS EN 13286-4. Compressive strength, indirect tensile strength, and abrasion resistance tests were conducted on samples prepared with a vibrating compactor. The experimental results showed that RCC mixtures with macro synthetic fiber reinforcement improved mechanical properties. The best strength results in compressive and indirect tensile tests were obtained with the addition of 0.60% macro synthetic fiber. It was observed that abrasion resistance also improved as the fiber content increased. In hybrid fiber tests conducted at a 0.60% macro fiber ratio, the optimal microfiber content was determined to be 0.10%. The use of hybrid fibers was found to improve the indirect tensile strength, abrasion resistance, and hydraulic permeability characteristics of RCC mixtures.