Bitumen is an organic substance widely used in laying highway pavement because of factors like cost, availability, curing time, and environmental effects. Given improper design of pavements and selection of materials, asphalt mixtures may not perform well against certain phenomena like aging, rutting, stripping, fatigue, and thermal cracking. Therefore, in order to improve the performance of asphalt mixtures, it is necessary to add modifiers to bitumen, such as polymers, rubber, and clays. Among the modifiers, styrene butadiene rubber (SBR) is one of the most useful and effective materials for paving. In this study, the effects of SBR/nanoclay (NC) and SBR latex on the rheological properties of bitumen and the performance of asphalt mixtures were assessed. SBR/NC and SBR latex were made and mixed with bitumen. The morphologies of the samples were verified by fluorescent microscopy. The results indicate that SBR/NC-modified bitumen improved the dispersion in the asphalt matrix. The addition of modi...

The main objective of this paper was to investigate the relationship between PCI and IRI values of the rural road network. To this end, 6000 pavement sections of the rural road network in Iran were selected. Road surface images and roughness linear profiles were collected using an automated car to calculate PCI and IRI, respectively. Three exponential regression models were developed and validated in three different IRI intervals. Analysis of the results indicated that exponential regression was the best model to relate IRI and PCI. In these models, R² values were found to be acceptable, equal to 0.75, 0.76, and 0.59 for roads with good, fair, and very poor qualities, respectively, indicating a good relationship between IRI and PCI. Moreover, validation results showed that the model had a high accuracy. Also, the relation between IRI and PCI became weaker as a result of increasing the level of road surface roughness, which can be caused by the increase in the number and severity of failures. Furthermore, two failures of rail R.C. and rutting were rarely observed in the studied roads. Therefore, the proposed model is more applicable for roads without the mentioned failures and asphalt‐pavement rural road network.

In this study, a composite of styrene butadiene rubber (SBR) and nano-clay was made with different ratios and used for bitumen modification. The results show that using nano-composites improves storage stability at high temperature. However, pure SBR modified bitumen is proved not to be stable at high temperature. Investigating the results of indirect tensile strength and indirect tensile strength ratio also indicates that nano-composites improve moisture sensitivity of hot mix asphalt (HMA). Further, according to the results, increasing the content of nano-clay enhances the resistant of asphalt mixtures against moisture damage.

The study described in this paper aims to establish the relationship between the chemical composition and rheological properties of asphalt binders in both the linear viscoelastic (LVE) and nonlinear viscoelastic (NLVE) domains. Two asphalt binders with different penetration grades were subjected to four distinct aging treatments of varying severity, resulting in changes in their chemical fingerprints. Chemical characteristics of the asphalt binders were analyzed using thin-layer chromatography (TLC), Fourier Transform infrared spectroscopy (FTIR), and gel permeation chromatography (GPC). Frequency sweep tests were conducted to evaluate the LVE behavior of the asphalt binders, while multiple stress creep recovery (MSCR) tests were employed to assess their NLVE properties. With regard to the LVE properties, rheological index ( R ) and zero shear viscosity (ZSV) derived from the Christensen-Anderson-Marasteanu (CAM) model exhibited high correlations with FTIR and molecular weight distribution (MWD) parameters. Additionally, the polydispersity index (PDI) displayed a stronger correlation with LVE-based parameters. Findings from the MSCR tests revealed that the sensitivity of the percentage recovery ( %R ) to chemical composition, as opposed to nonrecoverable creep compliance ( J _nr ), can be largely attributed to the degree of nonlinearity. Furthermore, it was observed that lower molecular weight molecules exert a greater influence on %R in the nonlinear domain. Finally, it was found that J _nrslope is a more reliable parameter than J _nrdiff for assessing the effects of chemical makeup on stress and temperature sensitivity.

To conserve natural resources and reduce waste generation, the effective valorization of industrial waste and byproducts in engineering applications is becoming increasingly important. Among these materials, aluminum production residues (APRs) offer a promising and sustainable solution for road pavement applications. Unlike previous reviews, this paper uniquely examines recent research on the use of various APRs in bituminous materials across multiple scales, with particular attention to their roles as additives and fillers. The APRs examined included red mud (RM), aluminum dross (AD), and spent pot lining (SPL) residues, as well as secondary aluminum waste (SAW). These materials have been employed as additives in asphalt binders (microscale), as fillers in asphalt mastics (mesoscale), and as additives or fillers in asphalt mixtures (macroscale). Overall, this review indicates that adopting appropriate treatment approaches for APRs as asphalt modifiers can enhance their dispersion, thermal stability, rheological behavior, and leaching performance. In particular, the use of RM has been shown to improve thermal stability, tensile strength, intermediate-temperature cracking resistance, and rutting resistance, largely due to the increased stiffness it imparts to asphalt mastic and mixture phases. However, there is no clear consensus among researchers regarding other properties, as performance outcomes depend strongly on multiple factors, particularly the physicochemical characteristics of the RM, filler–binder ratios, testing methods, and reference filler types. Other APRs—such as AD, SPL, and SAW—have also shown beneficial effects on the performance of asphalt mixtures. There is still limited research on the influence of APRs physicochemical variability on asphalt–filler interactions and the performance of bituminous materials. For the safe and large-scale adoption of APRs, it is essential to establish standardized characterization procedures, testing methods, and application guidelines while considering diverse climatic conditions. Comprehensive assessments of cost and environmental impacts should also be incorporated to support informed decision-making by engineers and industrial stakeholders.

This study focused on the characterization of sulfur-modified mortars made by amorphous carbon powder (ACP). To this end, modified paste samples were firstly fabricated with different ACP content considering different mixing times, and the modification degree induced from the presence of ACP was evaluated by X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR) and compressive strength tests. Then, the sulfur-modified mortar samples were made following the results of paste assessment. A series of properties of modified and raw sulfur mortar samples including mechanical performances (compressive and flexural strengths) and durability behaviors (water sorptivity and absorption, helium porosimetry, ultrasonic-pulse velocity (UPV), electrical resistivity, and rapid chloride permeability) were investigated. Microstructural investigation of paste samples showed that the degree of modification increased by increasing the ACP content and reducing the mixing time. Results on mortar samples obtained from mechanical measurments revealed that the addition of 20% ACP by weight of sulfur enhanced compressive and flexural strengths of mortar sample up to 26% and 57%, respectively which were in line with the outcomes from helium porosimetry and UPV tests. The incorporation of ACP led to a significant reduction in sorptivity and water absorption of mortar samples through enhancing the hydrophobicity properties of mortar. Durability assessments demonstrated that mortar samples containing ACP are less prone to corrosion damage compared to raw sulfur mortar. Consequently, using ACP could reduce allotropic transition and crystallization during the preparation of sulfur mortar resulting in higher mechanical and durability performance. However, this effect is less in samples including a huge amount of ACP.