Stone Mastic Asphalt Research Articles (Page 1)

Implementation of hydrated lime derived from scallop shell waste as mineral filler in Stone Mastic Asphalt (SMA) mixtures

Microwave heating is a method with a uniform heating effect and environmental friendliness in in-place hot recycling, but the microwave absorption capacity of traditional asphalt mixtures is still insufficient. As an excellent microwave-absorbing material, magnetite powder has the characteristics of high temperature resistance, corrosion resistance, and good thermodynamic stability. This study selects it as the microwave-absorbing material, prepares AC (Asphalt Concrete) type and SMA (Stone Mastic Asphalt) type microwave asphalt mixtures by adjusting its content, and investigates its influence on the microwave-heating characteristics and pavement performance of the mixtures. Simulations of the microwave-heating process of AC-type mixtures using COMSOL software (COMSOL Multiphysics 6.2) show that magnetite powder achieves optimal performance in terms of heating effect and economic efficiency when its content is 0.5%. Subsequently, laboratory tests are conducted to study the wave absorption and temperature rise performance of AC and SMA microwave asphalt mixtures; combined with economic factors, the optimal contents of magnetite powder for the two types of mixtures are determined to be 0.5% and 1%, respectively, and at the same time, these results are explained based on multiple physical theories. Furthermore, pavement performance is investigated through laboratory tests, including high-temperature rutting tests, low-temperature bending tests, immersed Marshall tests, and freeze–thaw cycle durability tests, and the results indicate that the high-temperature performance, low-temperature performance, and water stability of the microwave asphalt mixtures all meet the specification requirements for pavement performance. Subsequently, after 15 freeze–thaw cycles, the splitting tensile strength retention rate and stiffness modulus of the two types of mixtures show minimal differences from those of ordinary mixtures, and there is no durability degradation caused by the incorporation of magnetite powder. Finally, outdoor environment verification is carried out, and the results show that under complex conditions such as environmental factors, the wave absorption and temperature rise rates of AC and SMA mixtures at optimal contents are 52.2% and 14.6% higher than those of ordinary AC and SMA asphalt mixtures, respectively. In addition, these microwave asphalt mixtures have the advantages of both sustainability and reduced carbon emissions. By combining simulation methods and experimental verification, this study finally prepared two types of microwave asphalt mixtures with excellent performance, not only improving the microwave absorption and heating performance of asphalt mixtures, but also reducing environmental pollution and energy consumption, which conforms to the development of green transportation.

Introduction. Increasing the durability of pavement structures and harmonizing the national regulatory framework with European standards are key tasks for Ukraine’s road sector. The quality of stone mastic asphalt (SMA), as one of the most effective materials for surface courses, directly depends on the relevance of regulatory requirements. In Ukraine, these requirements were standardized by DSTU B V.2.7-127:2015 until 2024. However, in order to introduce modern approaches, a new standard, DSTU 9290-5:2024, has been developed and adopted. Problem Statement. Analysis shows that the requirements of DSTU B V.2.7-127:2015, although providing a basic quality level, had a number of shortcomings: insufficiently strict requirements for the geometric characteristics of aggregates, reliance on outdated nomenclature of bituminous binders, and most importantly, the absence of testing methods directly assessing asphalt performance, in particular rutting resistance. Such discrepancies with European practice restrained the real service life improvement of road pavements. Objective. To carry out a detailed comparative analysis of the requirements for stone mastic asphalt mixtures and SMA according to DSTU B V.2.7-127:2015 and the new DSTU 9290-5:2024, in order to identify key innovations and scientifically substantiate their impact on improving road construction quality. Methods. A comparative analysis of regulatory documents was conducted, including classification, requirements for components (aggregates, binders, additives), grading curves, physical and mechanical properties, as well as technological aspects and quality control methods. Results. It was established that the new DSTU 9290-5:2024 introduces fundamental changes. Requirements for aggregate particle shape were strengthened. The regulatory framework for binders was updated, emphasizing modern modified bitumens. The most important innovation is the introduction of mandatory rutting resistance testing, marking the first step towards performance-based evaluation. In addition, quality control was significantly reinforced by halving the batch size and integrating modern European testing methods from the EN 12697 series.

Hong Kong is one of the most densely populated cities in the world with a population of over seven million. Due to limited land resources, most residential buildings are high-rise structures of over 20 floors along the two sides of the roads. Similar to other major cities worldwide, road traffic noise is a notable nuisance in Hong Kong. All along, the Environmental Protection Department of the HKSAR Government had paid special attention and made significant efforts to tackle this challenge through comprehensive strategies. In addition to the adopted Low Noise Road Surfacing (LNRS) materials in Hong Kong, including Polymer Modified Friction Course (PMFC), Highly Modified Friction Course (HMFC), and Polymer Modified Stone Mastic Asphalt (PMSMA6), this paper reviews and discusses the recent trials and technical feasibility of the newly developed Highly Modified Stone Mastic Asphalt (HMSMA6) on local roads and provides updates about the newly published guidance note. Furthermore, the paper also provides a comprehensive comparison of various LNRS materials and their effectiveness in reducing noise generated from various road types in Hong Kong.

Current understanding of the load-transfer mechanism in the skeletal contact state of asphalt mixtures and its influence on macroscopic mechanical properties remains insufficient. This knowledge gap leads to difficulties in accurately predicting the performance of designed mixtures, thereby restricting the service life of asphalt pavements and the sustainable development of road engineering. This study investigated the skeletal contact characteristics, coarse aggregate movement, and crack propagation of three asphalt mixture types—Stone Mastic Asphalt (SMA), Asphalt Concrete (AC), and Open-Graded Friction Course (OGFC)—under loading. The methodology incorporated Computed Tomography (CT) technology, a Voronoi diagram-based skeletal contact evaluation method, and discrete element numerical simulation. The research aimed to elucidate the influence mechanisms of different skeletal structures on macroscopic performance and to validate the efficacy of the skeletal contact evaluation method. The findings revealed that under splitting load, the tensile stress contact force chains within the asphalt mixture’s skeleton were predominantly distributed along both sides of the specimen’s central axis. For all three gradations, compressive stress contact force chains (points) accounted for over 65% of the total, indicating that the asphalt mixture skeleton primarily bore and transmitted compressive stresses. The interlocking structure formed by coarse aggregates significantly enhanced the stability of the asphalt mixture skeleton, reduced its displacement under load, and improved the mixture’s resistance to cracking. In the three gradations, shear stress-induced cracks outnumbered those caused by tensile stress, with shear stress cracks accounting for over 55% of the total cracks. This suggests that under splitting load, cracks resulting from shear failure were more prevalent than those from tensile failure. SMA-20 demonstrated the best crack resistance, followed by AC-20, while OGFC-20 performed the poorest. These conclusions are consistent with the results of the Voronoi diagram-based skeletal contact evaluation, confirming the correlation between the contact conditions of the asphalt mixture skeleton and its mechanical performance. Specifically, inadequate skeletal contact leads to a significant deterioration in mechanical properties. The research results elucidate the influence of skeletal contact characteristics with different gradations on both mesoscopic features and macroscopic mechanical behavior, providing a crucial basis for optimizing asphalt mixture design.

The pavement industry faces challenges due to global warming and population growth, causing frequent rutting and fatigue cracking in the pavements. To combat these pressing issues, Stone Mastic Asphalt (SMA) can be a viable solution for heavy-traffic-prone road networks. However, polymer-modified asphalt binders and natural or synthetic fibers are typically required to prevent draindown because of their high binder content. Meanwhile, a huge amount of Banana fibers is disposed of in the form of waste generated by Banana cultivation, posing environmental challenges. Therefore, this research article investigates the effects of adding banana fibers to Stone Mastic Asphalt for sustainable and environmentally friendly road construction by utilizing agricultural waste. During the Modification of SMA Banana fibers at a fiber content of: 0.2%, 0.3%, and 0.4% with fiber lengths of 20mm, 25mm, and 30mm were examined based on draindown experiments, in which 0.3% was found to be optimum fiber content. The mechanical properties of banana fiber-modified stone mastic asphalt (BFM-SMA) prepared at optimum fiber content were compared to the conventional SMA using the Marshall Stability and Cantabro loss test. It has been discovered that the increased fiber length improves the mechanical characteristics of the BFM-SMA, as the modified SMA with banana fibers of 30mm length shows the best results, which strongly suggests that this approach could effectively address road problems.

Densification behavior of warm stone mastic asphalt with construction and demolition waste aggregate under repeated compressive loading

Cracking is a critical distress that reduces an asphalt pavement’s service life, and fiber reinforcement is an effective strategy to enhance anti-cracking capacity. However, the effects of fiber type, morphology, and length on key cracking modes remain insufficiently understood, limiting rational fiber selection in practice. This study systematically evaluated the influence of four representative fiber types on the anti-cracking performance of Stone Mastic Asphalt (SMA) mixture, combining mechanical testing and microstructural analysis. The fibers included lignin fiber (LF); polyester fiber (PF); chopped basalt fiber (CBF) with lengths of 3 mm, 6 mm, 9 mm; and flocculent basalt fiber (FBF). Key mechanical tests assessed specific cracking behaviors: three-point bending (low-temperature cracking), indirect tensile (tensile cracking), pre-cracked semi-circular bending (crack propagation), overlay (reflective cracking), and four-point bending (fatigue resistance) tests. A scanning electron microscopy (SEM) test characterized fiber morphology and fiber–asphalt interface interactions, revealing microstructural mechanisms underlying performance improvements. The results showed that all fibers improved anti-cracking performance, but their efficacy varied with fiber type, appearance, and length. PF exhibited the best low-temperature cracking resistance, with a 26.8% increase in bending strength and a 16.6% increase in maximum bending strain. For tensile and crack propagation resistance, 6 mm CBF and FBF outperformed the other fibers, with fracture energy increases of up to 53.2% (6 mm CBF) and CTindex improvements of 72.8% (FBF). FBF optimized reflective cracking resistance, increasing the loading cycles by 48.0%, while 6 mm CBF achieved the most significant fatigue life improvement (36.9%) by balancing rigidity and deformation. Additionally, SEM analysis confirmed that effective fiber dispersion and strong fiber–asphalt bonding were critical for enhancing stress transfer and inhibiting crack initiation/propagation. These findings provide quantitative insights into the relationship between fiber characteristics (type, morphology, length) and anti-cracking performance, offering practical guidance for rational fiber selection to improve pavement durability.

The stone–on–stone contact-interlocked skeleton structure of stone mastic asphalt (SMA) mixtures is crucial for the effective design of the mixture. However, existing skeleton structure discrimination standard (VCAmix < VCADRC) for SMA mixture gradation design is proven to necessitate calibration. To address this, a method was developed to analyse the influence of structural parameters on the high-temperature performance of SMA-13 mixture. And a skeleton structure discrimination standard for the SMA mixture was proposed and subsequently verified through the high-temperature performance of the SMA-13 mixture. The results indicate that variations in testing methods, compaction efforts, and coarse aggregate breakage lead to discrepancies between the key parameters VCADRC and VCAmix when evaluating the skeleton structure discrimination standard for SMA mixtures. Therefore, a volume method was introduced to the VCAmix expression, calculating it using the volume of the cylindrical specimen compacted by the VTM method. Additionally, the VCAmix < 0.95VCADRC(n=25) is recommended as the skeleton structure discrimination standard for SMA mixture gradation design. Which exhibited more prominent high-temperature performance (8% higher shear strength and 15% greater dynamic stability) than the SMA mixtures designed using VCAmix < VCADRC(n=25) as the skeleton structure discrimination standard.

Stripping and cracking resistance of sustainable warm stone mastic asphalt incorporating construction and demolition waste aggregates with digital image processing

Bitumen, the primary binder in asphalt concrete, lacks sufficient resistance to prolonged mechanical and environmental stress. To improve its durability, styrene-butadiene polymers are commonly used, although they are prone to oxidative degradation and phase instability. This study proposes a nanostructured approach to enhancing the stability and performance of polymer-modified bitumen (PMB) through the synergistic use of multiwalled carbon nanotubes (MWCNTs) and hydrocarbon plasticizers-specifically, selective oil refining extracts (SORE) and vacuum distillates (VD). Short-term oxidative degradation was assessed using isothermal RTFOT aging at 153, 163, and 173 °C. A classical first-order Arrhenius kinetic model was applied, with dynamic viscosity serving as a rheological proxy for SBS network integrity. Nanomodified compositions exhibited a 6-7-fold reduction in degradation rate constant (from 13.97 × 10⁻⁵ to 1.98 × 10⁻⁵ s⁻¹) and a 25-60% decrease in the preexponential factor, indicating suppressed molecular mobility and enhanced network cohesion. Performance was validated on SMA-16 specimens, showing up to 240% improvement in shear adhesion at 50 °C and 27% higher water resistance. Rutting resistance also increased, with rut depth reduced to 1.6–1.8 mm after 20,000 loading cycles. To integrate physical, mechanical, and durability characteristics, a set of Partial Quality Criteria (PQC) was developed and used to calculate a Generalized Effectiveness Coefficient (GEC), supporting multi-criteria optimization of asphalt mixtures. These findings confirm that nanostructured dispersed systems based on MWCNTs and hydrocarbon carriers not only delay oxidative degradation but also ensure multifunctional performance gains critical for high-traffic pavement applications.

Eco-friendly asphalt design: machine learning analysis of stone mastic asphalt containing shredded cigarette butt fibres

The effect of basalt, cellulose and blend fibers on deformation strength of stone mastic asphalt (SMA) containing reclaimed asphalt pavement (RAP)

Performance evaluation of stone mastic asphalt (SMA) containing reclaimed asphalt (RA) and biopolymer lignin

Compared to traditional dense asphalt concrete mixtures, stone mastic asphalt (SMA) generally offers superior performance in terms of its mechanical resistance and extended pavement lifespan. Focusing on the Norwegian scenario, this laboratory-based study investigated the durability of SMA considering the influence of the aggregate shape and petrography. The rock aggregates were classified according to three different-shaped refinement stages involving vertical shaft impact crushing. Further, the aggregates were sourced from three distinct locations (Jelsa, Tau and Dirdal) characterized by different petrographic origins: granodiorite, quartz diorite and granite, respectively. Two mixtures with maximum aggregate sizes of 16 mm (SMA 16) and 11 mm (SMA 11) were designed according to Norwegian standards and investigated in terms of their durability performance. In this regard, two main functional tests were performed for the asphalt mixture, namely resistance against permanent deformation and abrasion by studded tyres, and one for the asphalt mortar, namely water sensitivity. Overall, the best test results were related to the aggregates sourced from Jelsa and Tau, thus highlighting that the geological origin exerts a major impact on SMA’s durability performance. On the other hand, the different aggregate shapes related to the crushing refinement treatments seem to play an effective but secondary role.

Orthotropic steel bridge deck pavement is a critical technology ensuring the durability of orthotropic steel bridge decks. This paper analyzes core characteristics of four mainstream systems and systematically reviews research advances and engineering practices in steel bridge deck pavement: Guss Asphalt Mixture, Epoxy Asphalt Mixture, Stone Mastic Asphalt, and Epoxy Resin System. Future work must address bottlenecks in quantifying extreme climate-heavy load coupled damage, mitigating stress concentrations, and assessing long-term performance of low-carbon materials. Integrating intelligent monitoring technologies will drive pavement systems toward high-toughness ultrathin configurations and full-lifecycle reliability upgrades. This contributes to green pavement development trends under carbon neutrality goals and provides theoretical support for enhancing long-term service capacity of major infrastructure.

Conventional asphalt pavements face persistent distresses (rutting, cracking, moisture damage) under extreme environments and heavy traffic. Plant fibers (bamboo, coconut, sisal) emerge as sustainable modifiers, reducing life cycle carbon emissions by 30%-45% versus synthetic fibers while valorizing agricultural waste. Pretreatments (alkali, silane, acetylation) mitigate hydrophilicity, achieving up to 71.3% hemicellulose removal and enhancing fiber-asphalt interfaces. Performance evaluations demonstrate significant improvements: bamboo fiber enhances moisture stability by 20% and substitutes lignin in Stone Mastic Asphalt; coconut fiber (6% dosage) boosts complex modulus by 7.3 times in Trinidad Lake Asphalt and improves low-temperature cracking resistance; sisal fiber (0.3% dosage) enhances tensile strength by 15%-25% and fatigue life via ultra-high tensile strength (363 MPa-700 MPa). Future research should optimize fiber selection, develop eco-friendly treatments, and establish standardized durability guidelines for industrial adoption.

Epoxy Resin System (ERS) steel bridge pavement, which comprises a resin asphalt (RA) base layer and a modified asphalt wearing course, offers cost efficiency and rapid installation. However, the combined effects of traffic loads and environmental conditions pose significant challenges, requiring greater high-temperature stability than conventional pavements. The thermal sensitivity of resin materials and the use of conventional asphalt mixtures may weaken deformation resistance under elevated temperature conditions. This study investigates the thermal field distribution and high-temperature performance of ERS pavements under extreme conditions and explores temperature reduction strategies. A three-dimensional thermal field model developed using finite element analysis software analyzes interactions between the steel box girder and pavement layers. Based on simulation results, wheel tracking and dynamic creep tests confirm the superior performance of the RA05 mixture, with dynamic stability reaching 23,318 cycles/mm at 70 °C and a 2.1-fold improvement in rutting resistance in Stone Mastic Asphalt (SMA)-13 + RA05 composites. Model-driven optimization identifies that enhancing internal airflow within the steel box girder is possible without compromising its structural integrity. The cooling effect is particularly significant when the internal airflow aligns with ambient wind speeds (open-girder configuration). Surface peak temperatures can be reduced by up to 20 °C and high-temperature durations can be shortened by 3-7 h.

Influence of conductive fillers on the mechanical and thermal performance of stone mastic asphalt (SMA) mixtures

Use of engineered pellets containing E-cigarette butts and a recycling agent for stone mastic asphalt mixtures incorporating recycled asphalt