Articles
Publication Date: 2026
Journal of Materials in Civil Engineering (19435533)38(1)
Self-healing technology in asphalt mixtures offers significant potential for reducing construction, repair, and maintenance costs. While microcrack self-healing has been extensively studied, macrocrack self-healing remains largely unexplored. This study evaluates the use of discarded cigarette filters, containing heavy metals, as microwave-absorbing additives in stone mastic asphalt (SMA) to enhance macrocrack self-healing. Two incorporation methods, wet and dry mixing, were investigated. The semicircular bending (SCB) test, performed at 25°C and -12°C, assessed the self-healing performance using indices such as peak load (FMax) for microcracks, and fracture energy (Gf), crack resistance index (CRI), toughness index (TI), and balanced cracking index (BCI) for macrocracks. Results showed a 22% increase in Gf and significant improvements in BCI and TI by 25 and 22%, respectively, at 25°C with wet mixing. The wet mixing method demonstrated superior self-healing performance compared to the dry mixing method. Statistical analysis confirmed the significant effects of the mixing method and cigarette filter content on the TI and BCI indices. In addition, self-healing performance was better at 25°C compared to -12°C. Incorporating cigarette filters into SMA offers dual environmental and performance benefits, providing a sustainable solution for asphalt durability and waste management. © 2025 American Society of Civil Engineers.
Publication Date: 2025
Journal of Materials in Civil Engineering (19435533)37(12)
The rapid expansion of asphalt pavements worldwide has led to increased concerns regarding their deterioration, which incurs significant financial costs and environmental pollution. To mitigate such issues, the application of preventive maintenance treatments like microsurfacing before irreparable damage occurs is crucial. However, designing effective microsurfacing systems presents challenges, particularly in achieving stable asphalt emulsions. The use of suitable stabilizers can address these challenges. This study aims to fill the existing research gap by evaluating the performance of waste engine oil (WEO), waste cooking oil (WCO), and gas oil as stabilizers at three different concentrations. Additionally, to ensure the compatibility of these materials with other additives and to achieve a comprehensive assessment, three different penetration-grade bitumens, including one polymer-modified with polyphosphoric acid (PPA), were utilized. Furthermore, two distinct emulsifiers and two types of fibers - glass and polypropylene - were incorporated into the study. The performance of the microsurfacing mixtures was evaluated through a series of tests, including the cohesion test, wet-track abrasion test (WTAT), loaded wheel test (LWT), mixing time determination test, and consistency test. The results were subsequently analyzed using statistical methods. The findings revealed that gas oil exhibited the best performance as a stabilizer, followed by WCO and WEO. Moreover, the results indicated that the stabilizer type and concentration, as well as the emulsifier type, are critical parameters influencing the performance of microsurfacing systems. © 2025 American Society of Civil Engineers.
Goli, A.,
Sadeghi, P.,
Karimi, A.,
Shojaei, M.,
Kazemi, M. Publication Date: 2025
Journal of Materials in Civil Engineering (19435533)37(7)
The disposal of cigarette filters (CFs), primarily composed of cellulose acetate fibers and containing harmful substances like burned tobacco, tar, and heavy metals, poses a significant environmental threat due to their slow degradation. Thus, finding an effective approach for recycling and disposal is a pressing concern. Repurposing CFs in asphalt mixtures offers a promising recycling solution, particularly for improving asphalt crack resistance, which is crucial for performance but underexplored. This study evaluates the effects of incorporating intact and shredded CFs into stone mastic asphalt (SMA) under different wet and dry conditions on crack resistance. Semicircular bending (SCB) tests at 25°C and-12°C were conducted, examining two fracture modes (Mode I and Mixed Mode I/II). Key performance indicators like crack resistance index (CRI), balanced cracking index (BCI), toughness index (TI), peak load (Fmax), and fracture energy (Gf) were calculated. Results indicate that a 3% inclusion of shredded CFs significantly enhances crack resistance, with wet mixing showing the greatest improvements: Gf, CRI, and BCI increased by up to 46%, 15%, and 75% in Mode I, and 28%, 23%, and 76% in Mixed Mode I/II, respectively. Additionally, this study demonstrates the reliability of non-standard samples for SCB testing in mixed Mode I/II and emphasizes the critical role of CF quantity and the mixing method, with wet mixing proving notably more effective than dry mixing in improving the structural performance of asphalt. © 2025 American Society of Civil Engineers.
