The growing demands on global infrastructure highlight the critical need for durable and efficient pavement systems, particularly under the stress of repetitive heavy traffic loads. The use of geosynthetics within the pavement structure increases the load-carrying capacity of unbound pavement layers by providing lateral restraint, improving vertical stress distribution, and enhancing bearing capacity. Such reinforcement typically aims to either improve the service life of pavements or achieve equivalent performance with a reduced granular cover. Previous and ongoing research quantifies geosynthetic performance in pavement reinforcement using various testing methods. Among these, laboratory model box tests subjected to cyclic loading are pivotal, as they closely replicate real-world traffic conditions. Hence, these studies are essential for understanding how geosynthetics distribute loads and enhance pavement durability. This facilitates the development of optimized geosynthetic design and installation practices, accelerating the loading process to simulate years of traffic wear in a shorter period. This review discusses the improved rutting resistance of unbound pavements reinforced with geosynthetic materials, specifically drawing on data from cyclic plate load tests conducted on laboratory model boxes, as highlighted in the literature. Key variables such as optimum geosynthetic placement, geosynthetic material properties, performance of different geosynthetic materials and the effects of aperture shape and size on rutting resistance are discussed. Furthermore, the review assesses various predictive rutting models, analysing their applicability and accuracy in forecasting the rutting performance of geosynthetic-reinforced unbound pavements. This comprehensive literature review aids pavement engineers and researchers, in guiding the selection and design of geosynthetics to optimize pavement durability and functionality under repetitive traffic loads. • Discusses how geosynthetic reinforcement improves rutting resistance, extending the service life of unbound pavements. • Analyses model box test data under cyclic loading to identify key factors influencing rutting in reinforced pavements. • Evaluates and calibrates predictive rutting models using lab data to assess their applicability for reinforced pavement design

This research examined the feasibility of incorporating electric arc furnace (EAF) slag and waste plastic into stone matrix asphalt (SMA) mixtures. With annual global production of over 70 million tons of EAF slag and 300 million tons of plastic waste, repurposing these materials could yield substantial environmental benefits. The research evaluated SMA mixtures with EAF slag as aggregate replacement and waste plastic as a binder modifier. The research aimed to develop sustainable SMA formulations while promoting recycling of industrial byproducts. Laboratory experiments were conducted to evaluate mix design characteristics, drain-down potential, abrasion resistance, rutting resistance, moisture susceptibility, fatigue performance, and stiffness of modified SMA mixtures. The addition of waste plastic, ranging from 4%, 6%, 8% and 12% by weight of bitumen, demonstrated significant improvements in key properties. Results showed that waste plastic reduced the optimum binder content and increased voids in the mineral aggregate. EAF slag mixtures demonstrated improved drain-down characteristics and moisture susceptibility. Both rutting resistance and fatigue life increased significantly with waste plastic content, with EAF slag mixtures consistently outperforming those made with conventional aggregates. Ultrasonic pulse velocity tests indicated higher stiffness in modified mixtures. The optimal waste plastic content was determined to be 8% by weight of bitumen. Statistical analysis confirmed significant effects of both EAF slag and waste plastic on multiple performance parameters. These findings highlight the potential of incorporating industrial byproducts into SMA mixtures to achieve high-performance road construction solutions, offering a viable pathway for addressing global waste management challenges. • EAF slag and waste plastic improve rutting resistance and fatigue life in SMA mixtures. • SMA with EAF slag and 8% plastic resists deformation and cracking under heavy loads. • EAF slag enhances binder retention and reduces moisture susceptibility in SMA. • Combined use of EAF slag and plastic enhances long-term pavement durability and reliance on virgin materials

Enhancing rubber-bitumen compatibility is crucial to improve pavement performance and durability. To investigate the compatibility improvement between H2O2-activated waste crumb rubber (AWCR) and bitumen, coarse and fine waste crumb rubber (WCR) were treated and analyzed through multi-scale characterization and molecular simulation. Microstructure and chemical changes of WCR and AWCR were analyzed with scanning electron microscope (SEM), contact angle tests and Fourier transform infrared spectroscopy (FTIR). Compatibility was also indirectly evaluated through modified boiling tests and storage stability tests. Besides, molecular dynamics was used to explore the interaction between WCR/AWCR and bitumen. SEM, contact angle, and FTIR results showed bond breakage of CC and C–C and increased polar groups like –OH and –COOH in AWCR, resulting in a rougher texture and higher surface energy. Compared with WCR, AWCR showed a lower bitumen stripping rate after boiling, and the binder with AWCR also had a lower softening point difference and segregation rate after storage. Molecular dynamics simulations further confirmed that AWCR has a closer solubility parameter and higher binding energy to bitumen than WCR, reflected in a relatively slower diffusion rate. This study provides comprehensive evidence for an eco-friendly method of WCR surface treatment for more efficient recycling of tire rubber in asphalt pavements.