Juncus fibres’ treatment for use in stone matrix asphalt to improve its rutting resistance

This study investigated the effect of cellulose fibres extracted from Juncus plant stems on the rutting resistance of stone matrix asphalt (SMA). Replacing commonly used synthetic fibres with natural, locally available ones emerges as a sustainable solution, particularly given the growing demand for eco-friendly construction materials. Six chemical extraction treatments were tested, with alkalinisation at 98°C for 1 h in an 8% sodium hydroxide solution, followed by 1 h at ambient temperature in a 40% sodium hypochlorite solution, resulting in an optimal cellulose content of 64%. The extracted fibres were incorporated into SMA mixtures to assess their impact on performance. After determining the optimal asphalt content (OAC) through Marshall tests, two mixtures were selected: 6.2% OAC for SMA without fibres and 6.5% with 0.4% Juncus fibres. Performance was evaluated through Duriez compressive strength tests (18°C), gyratory shear compaction (155°C), and rutting wheel tests (60°C). Compared with the control mix, the compressive strength of the fibre-reinforced SMA was found to be 1.7 times higher, achieving 1% lower void content at 200 shear gyrations and 2.8 mm lower rutting depth at 30,000 wheel cycles. These findings demonstrate that Juncus fibres enhance SMA’s mechanical properties, contributing to more sustainable roadway infrastructure.