Investigation of the Fracture Mechanics Behavior an‎d Performance of Hot Mix Asphalt (HMA) Modified with Cellulose Nanocrystals (CNC)

9/6/2026 12:00:00 AM

Enhancing the durability an‎d performance of asphalt mixtures has always been one of the fundamental priorities in pavement engineering, an‎d the use of nanotechnology has emerged as a novel approach for achieving these improvements. Cellulose nanocrystals (CNC), owing to their favorable mechanical properties, biocompatibility, an‎d renewable origin, have been introduced as an innovative additive in asphalt pavements. However, comprehensive investigations into their effects on asphalt mixture performance, particularly at low temperatures are still limited. The main objective of this study was to eva‎luate the performance of CNC-modified hot mix asphalt (HMA) under low-temperature conditions, aging, an‎d freeze–thaw cycles, using a fracture mechanics approach an‎d the Balanced Mix Design (BMD) framework. The FTIR test was employed to assess asphalt binder aging, where an 80% improvement in aging resistance was observed in CNC-modified asphalt binder based on carbonyl content index. Cracking behavior of HMA mixtures with 0, 0.5, 1, an‎d 1.5% CNC was eva‎luated using Semi-Circular Bending (SCB) tests under Modes I an‎d II at low temperatures (0, –10, –20 °C), as well as under aging an‎d freeze–thaw cycles. Overall, CNC significantly enhanced fracture parameters, improved aging resistance, an‎d reduced moisture susceptibility under freeze–thaw conditions, particularly at the 1% level. Given the relatively low statistical significance of fracture energy parameter in aging an‎d freeze–thaw conditions as revealed by ANOVA, data augmentation up to 15 repetitions was performed using normal distribution methods an‎d machine learning models, including linear regression, KNN, ran‎dom forest, an‎d decision tree. Subsequently, a P-value-based sensitivity analysis was carried out to determine the appropriate number of laboratory repetitions required to achieve statistical significance. In addition, I-FIT, dynamic creep, an‎d moisture susceptibility tests were also conducted within the BMD framework. The results demonstrated that CNC addition up to 1% simultaneously improved rutting resistance, cracking resistance, an‎d moisture susceptibility, with 1% identified as the optimal dosage. Overall, the findings of this research confirm that CNC, as an emerging an‎d sustainable additive, has the potential to enhance the mechanical performance an‎d durability of asphalt mixtures an‎d can pave the way for designing pavements with superior an‎d more reliable performance under real service conditions

نانوكريستال سلولز , مخلوط آسفالتي داغ , مكانيك شكست , طرح مخلوط متعادل , پيرشدگي , چرخه ذوب و يخ

Cellulose nanocrystals , Hot Mix Asphalt , Fracture Mechanics , Balanced Mix Design , Aging , Freeze-Thaw Cycle

Hossein Tavakoli

Pooyan Ayar