تحديد خصائص المزيج الاسفلت الماستكي المحسنه بالالياف الصناعيه

Characterizing Stone Mastic Asphalt Mixture (SMA) Incorporating Hybrid Fiber Modified Binder

Abstract

Any national road network is critical to its economic development, social integration, and trade. The increase in maintenance costs corresponds to an increase in traffic volumes, necessitating the urgent need to build better, more durable, and more efficient roads that prevent or reduce bituminous pavement problems. The growing demand for high-quality pavements has encourage researchers to develop a new design procedure to improve the performance and prolong the life_span of asphalt pavements. Stone mastic asphalt (SMA) represents a technology used to improve the performance of asphalt mixtures. As well, these mixtures are characterized by their hardness, good stability and crack resistance that relies on the contact of rock stone for strength and the bond of a rich slurry for durability. The estimated cost increase of 20% to 25% is offset by an increase in the mix’s life expectancy, primarily due to decreased cracks and increased durability. SMA is an excellent combination to use in areas with high traffic volumes, and where frequent maintenance is costly.
On other hand, nowadays the concept of sustainability is a necessity (not a wish) in many aspects of life, including the pavements industry. The incorporation of waste materials into asphalt mixtures provides an excellent opportunity to manage waste sustainably. Cost reduction, environmental protection, and energy consumption reduction, all are contributed to sustainability. Accordingly, this research aims to investigate the impact of some local waste materials on the performance of the SMA asphalt mixture. Therefore, for neat asphalt binder modification, two types of waste materials were suggested: Recycled Low-Density Polyethylene (R-LDPE) and Waste Paper Fiber (W-PF). SMA was then improved using developed asphalt binders via R-LDPE at fixing dosages of (3%), and W-PF incorporated at three different dosages, namley0.3%, 0.5%, and 0.7% of binder weight, individually or collectively. Traditional tests such as penetration, softening point, ductility, penetration index, and rotational viscosity were used to characterize the modified asphalt binders. Moreover, the thin film oven test was used to verify the effect of aging. Furthermore, to determine the impact of using these materials on SMA mixture characteristics, the testing plan included volumetric properties (e.g., bulk density, air void, void in the mineral aggregate, void filled with asphalt, and draindown), mechanical properties (e.g., Marshall stability and flow, Creep Compliance, Indirect Tensile Strength, Cantabro abrasion loss, Skid Resistance and Wheel track), and durability (Cantabro abrasion loss after aging, and tensile strength ratio) properties.
Noticeably, the use of waste additives improves the physical properties of asphalt binder, i.e., the penetration, ductility, and temperature sensitivity of bitumen were reduced, while the softening point, viscosity, and aging resistance of bitumen were increased. Simultaneously, the incorporating of R-LDPE positively enhances the SMA mixture performance. Additionally, using W-PF individually, lead to enhance almost all stated characteristics, whereas 0.7% showed a significant improvement in comparison to other low ratios, except for 0.3 %, which showed a significant improvement in indirect tensile strength. Where the increase reached 33% and resistance to abrasion loss only where the increase in mixture resistance to abrasion reached 28% and 22% for unaged and aged conditions, respectively. The R-LDPE and W-PF blends resulted in additional SMA enhancement, with 3.7 % providing the best performance in the drain down, reaching 0.08 % and 0.15 % at 165°C and 180°C, respectively. Skid with a reduction of 28%, wheel track with a reduction of 28% Whereas the reduction in creep stiffness is greater than 60%, Where obtained that the higher enhancement reached 71 % in comparison to B0 mixture and the addition of 3.5 % providing the best results in improving the indirect tensile strength where the resistance of the mixture to cracking that by approximately 27 %. The study concluded that using local waste materials as modifiers for asphalt binder can improve sustainably the performance of SMA mixtures.