Effect of a New Additive Based on Textile Fibres from End-of-Life Tyres (ELT) on the Mechanical Properties of Stone Mastic Asphalt

Sustainable Asphalt Mixtures with Enhanced Water Resistance for Flood-Prone Regions Using Recycled LDPE and Carnauba-Soybean Oil Additive

This manuscript presents a comprehensive study on the sustainable optimization of asphalt mixtures tailored for regions prone to flooding. The research addresses the challenges associated with water damage to asphalt pavements by incorporating innovative additives. The study centers on incorporating recycled Low-Density Polyethylene (LDPE) and a tailored Carnauba-Soybean Oil Additive, advancing asphalt mixtures with a Control mix, LDPE (5%) + Control, and LDPE (5%) + 3% Oil + Control. A critical aspect of the research involves subjecting these mixtures to 30 wetting and drying cycles, simulating the conditions prevalent in tropical flood-prone areas. The incorporation of innovative additives in asphalt mixtures has demonstrated significant improvements across various performance parameters. Tensile Strength Ratio (TSR) tests revealed enhanced tensile strength, with the LDPE (5%) + 3% Oil-modified mixture exhibiting an impressive TSR of 85.7%. Dynamic Modulus tests highlighted improved rutting resistance, showcasing a remarkable increase to 214 MPa in the LDPE (5%) with a 3% Oil-modified mixture. The Semi-Circular Bending (SCB) test demonstrated increased fracture resistance and energy absorption, particularly in the LDPE (5%) with 3% Oil-modified mixture. Hamburg Wheel-Tracking (HWT) tests indicated enhanced moisture resistance and superior rutting resistance at 20,000 cycles for the same mixture. Cantabro tests underscored improved aggregate shatter resistance, with the LDPE (5%) + 3% Oil-modified mixture exhibiting the lowest weight loss rate at 9.820%. Field tests provided real-world insights, with the LDPE (5%) + 3% Oil mixture displaying superior stability, a 61% reduction in deflection, and a 256% improvement in surface modulus over the control mixture. This research lays the groundwork for advancing the development of sustainable, high-performance road pavement materials, marking a significant stride towards resilient infrastructure in flood-prone areas.

Enhancing Fatigue Resistance in Asphalt Mixtures with a Novel Additive Derived from Recycled Polymeric Fibers from End-of-Life Tyres (ELTs)

Waste-tire textile fibers (WTTF) represent a challenge for the recycling industry since there are currently very few alternatives for their use. In this study, an evaluation of the effect of a new additive developed in two granular formats from WTTF on the fatigue behavior of asphalt mixtures was performed. For the first format of the WTTF-based additive, its effect was evaluated on hot-mix asphalt (HMA), while for the second format of the additive, the effects were evaluated on stone mastic asphalt (SMA). This second format represents an alternative that allows for the total replacement of the cellulose stabilizing additive used in the reference mix. The evaluation of fatigue damage in the mixes was performed using the four-point bending beam (4PB) test specified in European standard EN 12697-24. The test results show that the asphalt mixtures manufactured with WTTF-based additives exhibited a higher capacity to resist load cycles before failure compared to the reference mixtures. Likewise, once the asphalt mixtures were evaluated in a pavement structure by means of an empirical mechanistic analysis, the pavement structures composed of asphalt mixtures with WTTF-based additives showed significant improvements in their durability for the different load axes evaluated. For an average thickness of 15 cm of asphalt mix of a pavement-type structure, the use of the WTTF additive increases the durability of the structures by up to 129% and 112% compared to the HMA and SMA reference mixtures, respectively. These results show that both formats of the WTTF-based admixture improve the fatigue damage resistance of the HMA and SMA asphalt mixtures.