Description
The synergy of using the textile fiber derived from end-of-life tires in the dry crumb rubber modified gap-graded asphalt mixtures
Witalij Zankowicz1, Krzysztof Maciejewski2, Anna Chomicz-Kowalska3, Przemyslaw Zaprzalski4
1Head of Road Technology R&D, Recykl O.O. S.A., Srem, Poland, w.zankowicz@recykl.pl
2Assistant professor, Kielce University of Technology, Kielce, Poland,
3Professor, Kielce University of Technology, Kielce, Poland, akowalska@tu.kielce.pl
4R&D Director, Recykl O.O. S.A., Srem, Poland, p.zaprzalski@recykl.pl
ABSTRACT. The constant growth in the number of vehicles on roads worldwide also requires continuous improvement of road technologies to ensure the preservation and enhancement of the reliability and durability of asphalt road pavements. Modifying bitumen with polymer components is the primary way to increase the strength and deformability of asphalt mixtures.
Due to the constant increase in traffic on modern roads, a greater degree of bitumen modification is required. The consumption of polymers is increasing (for example, in the case of highly modified bitumen, the polymer content of the SBS type exceeds 7%). This significantly increases road construction costs.
One of the promising and effective ways to increase the reliability, durability, and stability of road pavements, as well as reduce their impact on the environment, which have significant innovative potential, are wet, semi-wet, and dry technologies of the end-of-life tires (ELT) crumb rubber modified asphalt mixtures.
Wet technologies are more widely used, as they are more reliable and can be applied to a broader range of asphalt mixtures. The dry modification method is often hindered by the difficulties of asphalt mixture design and the level of reproducibility and uniformity of results in real conditions, especially for dense asphalt mixtures, which are currently the most widespread in the practice of asphalt pavement construction.
The present pilot study aimed to investigate the potential of enhancing the efficiency of dry and semi-dry methods for crumb rubber modified gap-graded asphalt mixtures by utilizing synthetic fibers from textile cords, which are also generated during tire processing, as a stabilizing, structuring, and strengthening component.
The study was conducted on mastics consisting of bitumen and mineral filler, in a ratio corresponding to the compositions of stone mastic asphalt mixtures (SMA), and additionally filled with micronized rubber powder and synthetic fiber. The mastics were subjected to tests to determine their rheological properties using MSCR (Multiple Stress Creep Recovery), DSR (Dynamic Shear Rheometer) and rotational viscometry.
The results of the conducted research on mastics of various compositions indicate the presence of a high level of synergy from the combined use of micronized rubber powder (MR powder) and synthetic fiber from end-of-life tires (ELTs). The presence of such synergy can help increase the efficiency of dry and semi-wet methods for crumb rubber modified gap-graded asphalt mixtures, including enhancing their reliability and durability, reducing the consumption of rubber powder, and decreasing bitumen consumption.
The experiment conducted on the SMA 8 asphalt mixture, which determined property indicators such as rutting depth, maximum structural strength, and binder drainage, also confirmed the existence of a synergistic effect from the combined use of micronized rubber powder and synthetic fiber from ELTs.
It is advisable to conduct further research on the effect of the properties and quality of micronized rubber powder and bitumen on the rheological properties of mastics and asphalt mixtures, as well as on the level of synergy from using MR powder together with ELT’s synthetic fibers as a stabilizing and modifying component.
Such a technology for crumb rubber-modified gap-graded asphalt mixtures may have prospects as being more technically, economically, and environmentally efficient compared to not only technologies for modifying asphalt mixtures with tire rubber by dry and semi-wet methods, but also traditional technologies for using bitumen modified with SBS-polymers.
KEYWORDS: asphalt rubber, crumb rubber, synthetic fibers, end-of-life tires, reliability, durability, elastic recovery, non-recoverable creep, dynamic viscosity, phase angle, complex shear modulus, synergy.
Reviews
There are no reviews yet.