Effects of hybrid basalt fiber dosages on workability and flexural strength of aerodrome concrete pavement

High-stress pavement systems, particularly aerodrome runways, demand concrete with superior crack resistance, flexural strength, and durability. Basalt fibers offer clear benefits for both mechanical strength and thermal resistance, but few studies have looked into using hybrid basalt fiber mixes specifically for pavements. In this work, we developed and fine-tuned a hybrid basalt fiber-reinforced concrete by blending micro- and macro-sized basalt fibers at a fixed overall fiber volume fraction, with the goal of boosting flexural performance combining basalt fibers of different sizes at different dosage combinations and micro-macro ratios to assess their impact on flexural performance and workability. Portland Cement M⁶⁰⁰ (CEM I 52.5) conforming to GOST 31 108−2020, potable water per GOST 23 732−79, and a polycarboxylate-based superplasticizer (0.7% cement weight) were used. Several basalt fiber ratios (micro and macro) were investigated. Mixing followed a controlled sequence to ensure uniform fiber dispersion, with specimens cured under moist conditions and tested for flexural strength at 28 days. Results indicated that hybrid mixtures out performed single-fiber systems in balancing early-age crack control and post-crack flexural strength. The 1.5:0.5 ratio achieved the highest overall flexural performance, showing a 7% improvement over pure macro fiber mixes and 5% over pure microfiber mixes at 28 days. Workability decreased with higher macro fiber content, highlighting the need for optimized dispersion. It is concluded that ratio micro-macro basalt fiber hybridization enhances pavement-grade concrete performance, with the 1.5:0.5 ratio recommended for aerodrome applications. Further research should evaluate long-term durability under cyclic loading and environmental exposure.