Comparative Study on the Low-Temperature Performance of Recycled Asphalt Treated with WR and WR/SBS Blends_Vol. 2 No. 3 (JCTE 2025)_Journal of Civil and Transportation Engineering (ISSN: 3005-5695)

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Comparative Study on the Low-Temperature Performance of Recycled Asphalt Treated with WR and WR/SBS Blends

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DOI: https://doi.org/10.62517/jcte.202506309

Author(s)

Yonghai Wang

Affiliation(s)

Shandong Taishan Road and Bridge Group, Tai’an, China

Abstract

The widespread adoption of reclaimed asphalt pavement (RAP) presents a sustainable solution to material scarcity in modern road construction; however, the degradation of low-temperature performance in aged binders remains a critical obstacle. Warm-mix rejuvenators (WRs) have emerged as viable modifiers for restoring binder ductility, yet their standalone efficacy under extreme cold conditions is often limited. This study investigates the potential of a direct-addition SBS modifier (DASBS), used in conjunction with WR, to enhance the low-temperature crack resistance of recycled asphalt systems. Three formulations—aged asphalt (A), WR-rejuvenated asphalt (WR+A), and WR/SBS-modified asphalt (WR/SBS+A)—were evaluated using Bending Beam Rheometer (BBR) testing at −12 °C, −18 °C, and −24 °C. The analysis focused on creep stiffness (S) and creep rate (m) as performance indicators. Results revealed that although WR+A showed moderate improvements, it failed to meet SHRP performance thresholds at −24 °C. In contrast, the WR/SBS+A formulation exhibited substantial reductions in S and corresponding increases in m across all temperatures, achieving full compliance with SHRP criteria. These enhancements were attributed to the synergistic mechanism between WR and DASBS: WR replenished light fractions and improved molecular mobility, while DASBS enabled in-situ polymer network formation that strengthened elastic recovery and reduced thermal brittleness. The findings confirm the effectiveness of DASBS as a direct-addition modifier and demonstrate its strategic relevance for cold-region pavement engineering requiring robust low-temperature durability.

Keywords

Recycled Asphalt Pavement; Warm-Mix Rejuvenator; Direct-Addition SBS; Low-Temperature Performance; Bending Beam Rheometer

References

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