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The development of asphalt mortar design methods is a prerequisite for cross-scale prediction from asphalt mortar scale to asphalt concrete scale. Existing studies have given some asphalt mortar design methods. However, these studies have not explored the impact of different maximum aggregate sizes of asphalt mortar on the cross-scale prediction results, nor have they judged the rationality of mortar design methods. In order to find the appropriate maximum particle size of asphalt mortar and develop an asphalt mortar design method that is suitable for predicting the mechanical behaviour of asphalt concrete, in this study, two commonly used particle sizes (2.36 and 1.18 mm) were selected as the maximum aggregate size of asphalt mortar, and an asphalt mortar design method, including the assumption of boundary particle size, was proposed. Then, utilising cross-scale simulation, the maximum aggregate size of asphalt mortar was compared and selected, and the rationality of the proposed asphalt mortar design method was verified. The results indicate that asphalt mortar with a maximum aggregate size of 1.18 mm is more suitable for predicting the mechanical behaviour of AC-13C, AC-20C, and AC-25C asphalt concrete. The design method of asphalt mortar containing the assumption of boundary particle size is reasonable. [ABSTRACT FROM AUTHOR]

The effect of different filler types on the properties of asphalt mortar before and after water saturation was studied by laboratory tests. Under both dry and water-saturated circumstances, four alternative fillers, limestone powder, hydrated lime, PO42.5 cement, and brake pad powder, are used, evaluated, and compared. The study methodology included characterizing the micromorphology, while X-ray diffraction imaging analysis and scanning electron microscopy were used to determine the chemical composition of the asphalt mortar following water saturation. To quantify the effects of moisture on the bonding mechanisms, surface energy concepts were employed to compute the surface free energy parameters of the asphalt mortar made with different filler materials. Dynamic shear rheometry was employed in the investigation to describe the rheological characteristics of the asphalt mortar as a function of filler under different water saturation conditions. The bonding strength of the asphalt mortars with various fillers was then quantitatively measured using pullout tests to account for the coupling effects of moisture and temperature. The findings of the laboratory tests generally showed that the asphalt mortar's effectiveness declined following moisture conditioning and saturation in water. However, hydrated lime, brake pad powder, and cement showed promise in strengthening the bonding of fillers and asphalt, with hydrated lime being superior. Likewise, the asphalt mortar's ability to tolerate moisture and resist water damage was also generally improved by hydrated lime. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Harbin Institute of Technology. Social Sciences Edition / Haerbin Gongye Daxue Xuebao. Shehui Kexue Ban is the property of Harbin Institute of Technology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Asphalt mortar is a mixture of asphalt mastic and fine aggregates (<2.36 mm) in asphalt concrete. Accurately predicting the complex modulus of asphalt mortar is essential to further estimating asphalt concrete's viscoelastic properties. However, existing analytical and numerical mesomechanical models generally underestimate the dynamic moduli of asphalt mortar and overestimate its phase angles, especially at high temperatures and low frequencies, because the solidifying reinforcement mechanisms are not considered. Also, the commonly used mesoscale division method for asphalt mortar, which takes asphalt mastic as the matrix phase, may lead to computational inefficiencies due to the presence of numerous fine aggregates. To address these issues, this study proposed a coarse asphalt mastic-based three-dimensional (3D) mesostructure model of asphalt mortar considering a conjunctive shell mechanism of interface transition zones (ITZs). A new mesoscale division method was proposed for asphalt mortar, which defines the coarse mastic incorporating the aggregates smaller than 0.6 mm as the matrix phase. A conjunctive shell mechanism of ITZs was proposed to account for the solidifying reinforcement effect due to the overlapped ITZs of closely adjacent aggregates. The results indicate that the overlapped ITZs led to the formation of the agglomeration networks of aggregates. The introduction of conjunctive shell mechanism of ITZs enabled accurate prediction of the complex modulus of asphalt mortar even at low frequencies and high temperatures and revealed the solidifying behaviors of asphalt mortar. The computational efficiency was substantially improved by introducing the coarse mastic matrix. [ABSTRACT FROM AUTHOR]

As the demand for sustainable and environmentally friendly road construction materials increases, corn stalk fiber modified with NaOH is a promising candidate due to its renewable and eco-friendly nature. This study employs an orthogonal experimental design to optimize the investigation of multiple factors (corn stalk fiber length, content, and modifier concentration) in the experiments, ensuring that the effects of different factors on the high and low temperature performance of asphalt binder can be independently estimated. Dynamic shear rheometer (DSR) and bending beam rheometer (BBR) tests were conducted. The bonding between fiber and asphalt was analyzed by infrared spectroscopy, and the action mechanism of fiber in asphalt was revealed from a microscopic perspective by scanning electron microscopy and fluorescence microscopy. Evidently, the concentration of modifier is the main factor affecting the rheological properties of fiber asphalt mortar. Considering the influence of various factors on the rheological properties of modified corn stalk fiber asphalt mortar, the optimal modifier concentration is 7%, the fiber length is 6mm, and the content is 1.5%. After adding modified corn stalk fiber, the asphalt mortar did not produce new characteristic peaks, and the fiber and asphalt were mainly bonded by physical action. The large surface roughness of the modified corn stalk fiber determines its good adsorption capacity, which is conducive to increasing the bonding force of the asphalt. Fibers with a large aspect ratio are easy to bridge with each other, restraining the expansion of cracks and thus enhancing the crack resistance of the mortar. [ABSTRACT FROM AUTHOR]

In this study, the feasibility of using bamboo bark fibers as modifiers to enhance asphalt mortar performance was investigated. Bamboo bark fibers were modified with NaOH, KH570 silane coupling agent, and nano-SiO2, and their preparation methods were established. The modified fibers were assessed for their oil absorption, thermal stability, and hydrophobicity. The asphalt mortar was evaluated for three key indicators: rutting resistance, deformation resistance, and durability at high temperatures. The microscopic morphology and modification mechanisms of the fibers were also studied. The results showed that modification with NaOH increased fiber porosity and surface roughness, while KH570 and its hydrolysis products enabled nano-SiO2 grafting onto the fibers, improving their adsorption to asphalt. The NaOH-KH570-nano-SiO2 ternary-composite-modified bamboo bark fiber (NKSBF) demonstrated superior hydrophobicity, oil absorption, and thermal stability at the asphalt mixing temperature. Among the modified fibers, asphalt mortar containing 3% NKSBF showed the best performance based on three key indicators, increased the shear strength by 96.4% and the softening point by 7.1% compared to the base asphalt, and increased the ductility by 1% compared to lignin fiber asphalt mortar. The incorporation of 3% bamboo bark fibers improved the rutting resistance, deformation resistance, and durability of short-term-aged asphalt mortar, with NKSBF showing the most significant improvement. [ABSTRACT FROM AUTHOR]

The size of the representative volume element (RVE) for the two-dimensional (2D) random aggregate numerical model of asphalt mortar in a non-destructive state, which directly affects the time required to simulate the linear viscoelastic behavior from asphalt mastic to asphalt mortar. However, in the existing literature, limited research has been conducted on the size determination of the numerical model RVE for asphalt mortar. To provide a recommended size for the typical 2D random aggregate numerical model RVE of asphalt mortar in a nondestructive state, this paper first applies the virtual specimen manufacturing method of asphalt concrete 2D random aggregate to asphalt mortar. Then, it generates numerical model RVEs of asphalt mortar with different maximum particle sizes, after which geometric and numerical analyses are conducted on these models. Finally, based on the geometric and numerical analysis results, the recommended minimum sizes of RVE for the 2D asphalt mortar numerical model are provided. [ABSTRACT FROM AUTHOR]

Copyright of Bulletin of the Chinese Ceramic Society is the property of Bulletin of the Chinese Ceramic Society Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The direct action of salt on asphalt materials has received limited research despite the abundance of studies on salt erosion and its effects on the moisture stability of asphalt concrete. This study aimed to investigate the effects of chloride salt on the rheology of asphalt and erosion mechanisms. Microscopic properties of asphalt mortar were analyzed through scanning electron microscope (SEM) and Fourier transform infrared spectroscopy (FTIR), and the erosion degree of salt in asphalt mortar was evaluated based on three major indexes. Rheological properties of asphalt mortar were determined through temperature sweep and multiple stress creep and recovery (MSCR) tests, while the modified water-boiling test was conducted to evaluate the adhesion of asphalt mortar. Results showed that as salinity increases, the agglomerate phenomenon tends to occur in asphalt mortar, leading to physical aging effects on its basic properties. Meanwhile, chloride salt modified asphalt concrete is prone to cracking at low temperatures and has reduced durability at high temperatures, making it unsuitable for standard load or heavy traffic pavement requirements of PG64 modified asphalt. Furthermore, the presence of chloride in asphalt mortar was not conducive to its adhesion. [ABSTRACT FROM AUTHOR]

The objective of this study is to unravel the modification mechanism of a coupling agent on the water sensitivity of phosphogypsum asphalt mortar. The adhesion process of phosphogypsum asphalt mastic modified with three kinds of coupling agents (KH-550, KH-570, and CS-101) and raw phosphogypsum to the aggregate minerals was simulated based on the molecular dynamics software, Materials Studio 2020, and the water film layer was considered along the simulation. When the three coupling agents were added, the interfacial adhesion work gradually increased with the increase of modified phosphogypsum dosage, and the trends of each model were relatively similar. With the increase of simulation time, the mean square displacement of water molecules of the three interfacial models showed different trends, and the increasing trend rank was unmodified phosphogypsum > KH-550 > KH-570 > CS-101. The diffusion coefficient of the water molecular layer of asphalt mastic modified with CS-101 coupling agent in phosphogypsum shows a significant decrease with the increase of CS-101-modified phosphogypsum (more than 5% mass ratio to asphalt). Compared to raw phosphogypsum asphalt mortar, the addition of coupling agents can significantly limit the diffusion of water molecules and effectively improve the interfacial adhesion work, in which CS-101 coupling agent has the best effect, followed by KH-570 and KH-550. [ABSTRACT FROM AUTHOR]

High titanium heavy slag powder (HSP) is a typical waste with vast reserves but lacks effective disposal. This paper investigated for the first time the potential of reusing HSP as a sustainable mineral filler for asphalt mixtures. Firstly, a comprehensive comparison and analysis of the physicochemical properties of HSP and limestone powder (LSP) were conducted. Subsequently, asphalt mortars were designed, incorporating four filler-to-asphalt ratios (F/A of 0.2, 0.3, 0.4, 0.5) and five levels of HSP substitution for LSP (0%, 25%, 50%, 75%, 100%). Finally, selected properties of twenty types of asphalt mortar were tested. Compared with LSP, the HSP presented a coarser surface, more pores, smaller particle size and larger specific surface areas, which were conducive to the formation of more “structured asphalt”. Moreover, the chemical composition of HSP was complex, but it did not leach toxic elements, and the volume stability, high temperature stability, radioactivity met the requirements. However, its alkalinity was significantly lower than that of LSP, indicating weaker interactions with the asphalt. At F/A ratios of 0.2 and 0.3, the replacement of LSP with HSP resulted in a slight decrease in high temperature properties of asphalt mortars, but an improvement in low temperature performance. However, a further increase in the F/A ratio revealed an opposite trend. The properties of asphalt mortars were influenced by the combined effects of the chemical composition and physical properties of HSP. The FTIR test results indicated that no new functional groups were formed between the HSP and asphalt, suggesting primarily physical interactions.

As an additional product in the production of recycled aggregate from construction waste, the research on the reclaim of recycled fine powder is still insufficient. In this paper, recycled concrete micropowder (RCP) was used as asphalt filler to study the interaction mechanism of RCP modified asphalt mortar. The microcosmic morphology of RCP, LSP and the coating of asphalt were observed by ESEM, the infrared spectrum characteristics of asphalt mortar were tested by FTIR, and the interaction between asphalt and RCP and LSP was explored by analyzing the changes of characteristic peak functional groups between asphalt and two fillers. Based on the rheological parameters of dynamic shear rheological test, the interaction evaluation index based on complex shear modulus is selected, and the grey correlation analysis is used to analyze the correlation degree between the evaluation index and ratios of filler to asphalt and RCP content. The results show that the increase of ratios of filler to asphalt and RCP content can enhance the interaction, and the influence of ratios of filler to asphalt on the interaction between filler and asphalt is greater than that of RCP content; There is no obvious chemical interaction between RCP and LSP and asphalt, which is mainly physical adsorption; The complex shear modulus coefficient ΔG* (ω) is a more reasonable index to evaluate the degree of interaction between RCP and asphalt. [ABSTRACT FROM AUTHOR]

In order to evaluate the feasibility of steel slag powder as filler, the coating properties of steel slag and limestone aggregate were compared by water boiling test, the micro morphology differences between steel slag powder and mineral powder (limestone powder) were compared by scanning electron microscope (SEM), and the high-temperature rheological properties of asphalt mortar with different ratio of filler quality to asphalt quality (F/A) and different substitution rates of mineral powder (S/F) were studied by dynamic shear rheological test. The results show that the surface microstructure of steel slag powder is more abundant than that of mineral powder, and the adhesion of steel slag to asphalt is better than that of limestone. At the same temperature, the lower the ratio of S/F is, the greater the rutting factor and complex modulus will be. In addition, the complex modulus and rutting factor of the asphalt mortar increase with the increase of F/A, and the filler type and F/A have a negligible effect on the phase angle. [ABSTRACT FROM AUTHOR]

This study aims to investigate the effect of the mesoscopic characteristics of mineral powder fillers on the rutting resistance of asphalt mortar. Extraction and sieving tests were used to obtain the buton rock asphalt (BRA) ash with particle size smaller than 0.075 mm, which is consistent with that of the conventional mineral powder. The mesoscopic characteristics of BRA ash and conventional mineral powder were measured by SEM image analysis and the osmotic free pressure water method. Mesoscopic structure models of structural and free asphalts in mortar were obtained. The 70# matrix asphalt was used to prepare two kinds of asphalt mortar with BRA ash and conventional mineral powders fillers. The rutting factor of the two asphalt mortars was tested by dynamic shear test (DSR). Test results show that the ash extracted from BRA has a similar mesoscopic classification with the conventional mineral powder. Still, its fractal dimensions are larger, indicating the particles in BRA ash have more complex shapes and rougher surfaces, which is beneficial for forming structural asphalt and subsequently increasing the rutting factor (G*/sinδ), i e, improving the rutting resistance of the asphalt mortar. [ABSTRACT FROM AUTHOR]

Copyright of New Building Materials / Xinxing Jianzhu Cailiao is the property of New Building Materials Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

To understand the effects of filler-asphalt ratio on different properties of lignin and polyester fiber reinforced shape memory polyurethane (SMPU)/styrene butadiene styrene (SBS) composite modified asphalt mortar (PSAM), as well as to reveal the reinforcing and toughening mechanisms of lignin and polyester fibers on PSAM, SMPU, SBS and mineral powder were first utilized to prepare PSAM. Then the conventional, rheological and anticracking properties of lignin fiber reinforced PSAM (LFAM) and polyester fiber reinforced PSAM (PFAM) at different filler-asphalt ratios were characterized. Test results indicate that the shear strength, deformation resistance and viscosity are increased after adding 0.8wt% lignin fiber or polyester fiber and increasing the filler-asphalt ratio from 0.8 to 1.2. The optimal filler-asphalt ratio of 1.0 is proposed after comprehensive performance assessments of PSAM. Polyester fiber shows a better reinforcing effect than lignin fiber, but its improvement in the thermal stability of PSAM is not significant at high temperatures. Additionally, the complex modulus, storage modulus, loss modulus and rutting resistance factor of PSAM are improved after adding lignin fiber and polyester fiber, as well as show an increasing trend as the filler-asphalt ratio is raised, but the phase angle is gradually decreased. Further, the increase of elastic components in PSAM effectively enhances the anti-deformation ability of PSAM at high temperatures, and polyester fiber more obviously improves the high-temperature deformation resistance of PSAM than lignin fiber. Finally, the anti-cracking performance of PFAM and LFAM at low temperatures is reduced by 74.2% and 46.7%, respectively, as the filler-asphalt ratio is raised from 0.8 to 1.2. The low-temperature anti-cracking performance of LFAM is lower than that of PFAM at the same filler-asphalt ratio, even lower than that of PSA. Compared with lignin fiber, the anti-cracking performance and deformation resistance of PSAM at low temperature is more greatly enhanced by polyester fiber. [ABSTRACT FROM AUTHOR]

The performance of an asphalt mixture is significantly affected by the properties of its asphalt mortar, which consists of an asphalt binder, mineral fillers, fine aggregates and air voids. The aim of this work was to evaluate the correlations between the high-temperature performance of an asphalt mixture and the rheological properties of its corresponding asphalt mortar. The multisequence repeated loading (MSRL) test was used to estimate the high-temperature performance of the asphalt mixture. Six different gradations, AC-13, SMA-13, SUP-13, AC-20, SUP-20 and AC-25, and two styrene–butadiene–styrene (SBS)-modified asphalt binders were considered and used to prepare the asphalt mixture specimens. The gradations and asphalt types of asphalt mortars were consistent with their asphalt mixtures. A modified multiple-stress creep–recovery (MSCR) test was proposed for evaluating the rheological properties of asphalt mortar with a dynamic shear rheometer (DSR). Based on the basic form of the Hirsh model, a multiple regression model was established, and its coefficient of determination (R-square) was 0.96. The rheological response of the asphalt mortar presented great correlation with the high-temperature behaviour of the asphalt mixture. In addition, the MSCR indicators (nonrecoverable compliance and percent recovery) obtained at 12.8 kPa creep stress represented the rheological status of asphalt mortar in asphalt mixture well. Therefore, the mechanical behaviours of asphalt mixture at high temperature could be accurately predicted by the MSCR indicators of asphalt mortar and its coarse aggregate parameters. [ABSTRACT FROM AUTHOR]

Matrix and SBS modified asphalt mortar were prepared by replacing mineral powder with cement under different filler-asphalt ratios. The variation laws of ductility, softening point, penetration, cone penetration, and Brookfield rotational viscosity of the two kinds of pastes with filler-asphalt ratio were studied. The shear strength of the two kinds of asphalt mortar was calculated. And the viscosity-temperature curve was established. The best filler-asphalt ratio was recommended. The results show that the addition of cement and the increase of filler-asphalt ratio will reduce the ductility, penetration, and cone penetration of asphalt mortar, while improve the softening point, shear strength, and viscosity. In a specific range of filler-asphalt ratios, cement can improve the high-temperature performance of asphalt mortar without significant impact on the low-temperature performance. [ABSTRACT FROM AUTHOR]

Moisture damage is one of the undesired distresses occurring in flexible asphalt pavements, mostly through water intrusion that weakens and ultimately degrades the asphalt mortar-aggregate interfacial bond. One method to mitigate this distress is using anti-stripping or anti-spalling filler materials that, however, require a systematic quantification of their interfacial bonding potential and moisture tolerance properties prior to wide-scale field use. With this background, this study was conducted to comparatively evaluate and quantitatively characterize the moisture sensitivity and water damage resistance of the interfacial bonding between the asphalt mortar and aggregate fillers. Using an in-house custom developed water-temperature coupling setup, numerous laboratory pull-out tests were carried out on the asphalt mortar with four different filler materials, namely limestone mineral powder, cement, slaked (hydrated) lime, and waste brake pad powder, respectively. In the study, the effects of moisture wet-curing conditions, temperature, and filler types were comparatively evaluated to quantify the water damage resistance of the asphalt mortar-aggregate filler interface. For interfacial microscopic characterization, the Image-Pro Plus software, 3-D digital imaging, and scanning electron microscope (SEM) were jointly used to measure the spalling rate and the surface micromorphology of the asphalt mortar and aggregate filler before and after water saturation, respectively. In general, the pull-out tensile force exhibited a decreasing response trend with more water damage and interfacial bonding decay as the moisture wet-curing temperature and time were increased. Overall, the results indicated superiority for slaked (hydrated) lime over the other filler materials with respect to enhancing and optimizing the asphalt mortar-aggregate interfacial bonding strength, moisture tolerance, and water damage resistance, respectively—with limestone mineral powder being the poorest performer. [ABSTRACT FROM AUTHOR]

This study introduced phosphogypsum coupled with steel slag powder to prepare the phosphogypsum based filler (PF) for asphalt mixture. Penetration, penetration index, softening point, ductility, equivalent softening point, moisture stability of asphalt mortars with different steel slag powder content, filler-asphalt ratio, and PF content were studied. Mechanical properties of PF based asphalt mortar (P-AM) were then analyzed to determine the optimum steel slag content in PF. Overall desirability method was used to determine the optimum replacement ratio of PF content in limestone filler. Rheological properties of P-AM were also analyzed through dynamic shear rheometer. Volumetric performance, high-temperature performance, low-temperature performance, and moisture stability tests were carried out on PF based AC-20 asphalt mixture. Results showed that P-AM presented the optimum performance when the content of steel slag powder was 23% by mass of phosphogypsum. Fatigue and rutting factor of asphalt mortar were enhanced by PF. The optimum PF content in replacing limestone filler was 75% through overall desirability evaluation. PF developed the high-temperature performance and moisture stability of asphalt mixture. Additionally, volumetric and low-temperature performance were not significantly affected by PF. It is suggested that using PF which is based on phosphogypsum as a filler of asphalt mixture to partially replace traditional limestone filler was adequate. [ABSTRACT FROM AUTHOR]

In order to explore the applicability and feasibility of accelerated fatigue test method in evaluating the fatigue performance of asphalt mortar, frequency scanning test, dynamic mechanical analysis slice test, linear amplitude scanning test and four-point bending fatigue test were carried out on waterborne epoxy emulsified asphalt mortar (AC5-WEREA), modified asphalt mortar (AC5-SBS) and matrix asphalt mortar (AC5-70#) under bending and tensile stress mode, and the test results were compared and analyzed. The test results show that the fatigue life results of asphalt mortar determined by dynamic mechanical analysis slice test, linear amplitude scanning test and four-point bending fatigue test have the same trend. It is further concluded that the accelerated fatigue test method is not only applicable and feasible in evaluating the fatigue performance of asphalt mortar, but also the size of the specimen required for dynamic mechanical analysis slice test is small, which can effectively reduce the variability of the test results. [ABSTRACT FROM AUTHOR]

Utilizing agricultural waste rice straw as fiber and filler in asphalt pavement is a win-win strategy for environmental protection and cost reduction. This study investigated the properties of asphalt binder and asphalt mortar with rice straw fiber or filler and elucidated the interaction mechanism between asphalt binder and rice straw products. The results revealed that adding rice straw fiber decreased the penetration by over 30 % while increasing the softening point by more than 13 % and the viscosity of the asphalt binder. The addition of 8 % rice straw fiber or 50 % filler improved the complex modulus and Superpave rutting parameter G */sin δ of both asphalt binder and asphalt mortar through DSR tests. Additionally, BBR test results indicated that the creep stiffness of asphalt binder and asphalt mortar initially decreased by over 10 % and then increased by 5–50 % with higher rice straw fiber or filler content, a trend that contrasted with the behavior of the m-value. Molecular models of asphalt binder and rice straw products were established based on molecular dynamics to evaluate the diffusion characteristics of asphalt binder. It revealed that higher temperatures enhanced the diffusion of asphalt binder on cellulose surfaces. And it has a greater adsorption effect on asphalt binder at the amorphous region of cellulose compared with that at the crystalline region. • Adequate addition of rice straw products improves G * and G */sin δ of asphalt binder. • Rice straw products can enhance the low-temperature properties of asphalt binder. • Higher temperatures promoted the diffusion of asphalt binder on cellulose surface. • The amorphous region of cellulose exhibited a greater adsorption. [ABSTRACT FROM AUTHOR]

The severe agglomeration of Reclaimed Asphalt Pavement (RAP) particles not only leads to high gradation variability during recycling, but also impedes the miscibility between new-old binders. This phenomenon imposes significant limitations on maximizing the utilization of RAP with high content and value. This paper first realized the effective separation of asphalt milling material by the self-developed RAP refined processing equipment to obtain coarse RAP with low binder content and fine RAP with high binder content. The fine RAP with high binder content underwent a deep rejuvenation process, and the recovery efficiency of the asphalt mortar was evaluated by CT scanning test, microscope observation test, and dynamic shear rheology test. Moreover, to investigate the strength formation characteristics of recycled asphalt mixtures with high RAP content, specific tests including wheel tracking test, three-point bending test, Hamburg Wheel Tracking test, dynamic modulus test, and two-point bending fatigue test, were conducted. By using the refined processing equipment, the asphalt film on the RAP can be precisely removed, thereby addressing the issue of aged binder agglomeration. In the coarse RAP with low binder content, the binder content was reduced to 1.48 %, allowing it to be used as a direct substitute for new aggregate, whereas the binder content of fine RAP exceeded 10 %. It was found that the direct incorporation of unrefined RAP enhanced the high-temperature stability and dynamic modulus of recycled asphalt mixture, but impacted their low-temperature cracking resistance, moisture stability, and fatigue performance. After refined processing and differentiated recycling design, the agglomeration of aged binder was reduced and the miscibility of new-old binders was improved, effectively enhancing the comprehensive performance of the recycled asphalt mixture. It should be noted that the mixing homogeneity and miscibility decrease as the RAP content exceeds 75 %, resulting in the reduction of moisture stability, cracking resistance, and fatigue performance of recycled asphalt mixture. • Reclaimed Asphalt Pavement is a waste product generated during pavement maintenance and causing serious environmental problems. • This paper employed the self-developed RAP refined disposal equipment by using coarse RAP aggregate self-grinding and fine RAP aggregate self-spraying grinding technology, which realized the separation of aged binder and aggregate. • It was concluded that using refined disposal RAP materials and differentiated regeneration process, 75 % of RAP content can be recycled and reused in recycled asphalt mixtures. [ABSTRACT FROM AUTHOR]

The accumulation of graphite tailings (GT) in the tailings dam has caused severe damage to the ecological environment. This study investigates the feasibility of using GT as an alternative aggregate to fine aggregates (FA) in asphalt mortar. Various analytical tools, including a laser particle size analyzer, scanning electron microscope, X-ray diffractometer, and X-ray fluorescence, were utilized to characterize the properties of GT and FA. Asphalt mortar was prepared with four aggregate/asphalt weight ratios (0.3, 0.6, 0.9, 1.2). Scanning electron microscopy and FTIR spectroscopy were used to analyze the asphalt mortar's surface morphology and blending mechanism. The rheological properties of the asphalt mortar were evaluated using rotational viscosity test, dynamic shear rheological test, and bending beam rheological test. The environmental and economic aspects of GT were assessed through leaching toxicity and cost-benefit analysis. The results showed that GT has larger particle size and rougher surface, promoting better bonding with asphalt. With increasing GT content, the viscosity, complex modulus, rutting factor, and creep stiffness of the asphalt mortar also increased, indicating improved rheological, stiffness, and elastic properties. GT was found to pose no risk for large-scale use as a building material and can offer substantial economic benefits. The study concludes that utilizing GT in asphalt pavement engineering benefits environmental protection. [Display omitted] • GT improve the rheological properties of asphalt mortar. • GT have low toxicity in short-term leaching. • The utilization of GT provides a good economic profit for enterprises. [ABSTRACT FROM AUTHOR]

To confirm the feasibility of waste incineration fly ash applied in asphalt pavement materials, the waste fly ash from the waste incineration station in Dongguan (DG-FA) and Guangzhou (GZ-FA) were selected as mineral filler replacing limestone powder (LF) to prepare asphalt mortar. The physical properties, chemical composition, and thermal characteristics of FA were analyzed. The effect of FA on the physical properties and rheological properties of asphalt binder was investigated systematically. The micromorphology of FA asphalt mortar was characterized. Finally, the blocking effect of asphalt binder on the leaching of toxic elements from FA was evaluated through XRF test. The results showed that the granular composition of FA particles was similar to that of LF. Furthermore, compared to LF, the specific surface area and the pore structure of FA were more developed, and the high active amorphous material was higher. Adding FA to asphalt mortar and increasing replacing amount improved its high-temperature rutting resistance as well as its ability to adhere to asphalt, while the low-temperature crack resistance was decreased. Further, the asphalt binder provided the good shielding effect against the migration of heavy metals in FA. While the leaching concentration of Pb element slightly exceeded the hazardous waste leaching standard (GB5085.3–2007), the remaining elements met the standard requirements. Overall, FA improved asphalt mortar performance, and the asphalt had a good curing and stabilizing effect on the toxic elements in fly ash, indicating that FA could be used as a filler in asphalt pavements. [ABSTRACT FROM AUTHOR]

Copyright of Science Technology & Industry / Keji he Chanye is the property of Chinese Society of Technology Economics and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The two-dimensional (2D) discrete element model (DEM) of semi-flexible pavement (SFP) is utilized to understand displacemental and mesomechanical responses of SFP under different wheel loads. Simulation results indicate that when the wheel load is increased, the changing tendency of vertical displacement is basically proportional to the wheel load change. The bulging on both sides of wheel load range becomes more obvious and the bulging range is also increased. The vertical displacement is decreased, but its decreasing rate becomes larger with the increase in wheel load when the pavement depth is increased. Additionally, most compressive stress of SFP is borne by the skeleton structure composed of aggregate and hardened cement mortar, and shows an important role during the transfer of compressive stress. The interfacial compressive stress between hardened cement mortar and aggregate is largely distributed along the vertical direction. Further, the tensile stress mainly distributes at the material interface which is in contact with asphalt mortar. The tensile stress mainly appears around aggregate and cement mortar in the horizontal direction. The existence of tensile stress ensures the structural stability of pavement. Finally, the shear stress is easy to appear in asphalt mortar. The interfacial shear stress between hardened cement mortar and aggregate shows the vertical distribution. The skeleton structural stability of SFP is directly determined by the shear strength of pavement material. This study lays the foundation to reveal the formation mechanism of rutting and crack of SFP. [ABSTRACT FROM AUTHOR]

Many research studies have been conducted on the ultraviolet (UV) ageing performance of asphalt and asphalt mixture, but the superposition relationship between the loading time–temperature and the aggravation of UV ageing degree is still lacking. In this research, the dynamic modulus of styrene butadiene styrene (SBS) polymer-modified asphalt mortar, under different UV intensities, UV ageing time and loading temperatures, was obtained by the dynamic modulus sweep test at different temperatures. The results showed that the dynamic modulus decreases with the increase of temperature, and increases with the increase of UV ageing time and intensity. To further evaluate the UV ageing of asphalt mortar, the time–temperature superposition has been expanded to incorporate the UV ageing time and intensity, and the dynamic modulus curves of asphalt mortar under different UV ageing time or intensities and temperatures were constructed through superposition shift equations. The results showed that the reduced UV ageing time or intensity increases with the decrease of test temperature. Based on the superposition relationship of time–temperature–UV ageing degree (radiation time and intensity), the comprehensive shift factor functions were determined. These superposition equations conducted in this research provided meaningful predictions for different UV ageing time and intensity conditions. [ABSTRACT FROM AUTHOR]

Fiber has an important influence on the performance of asphalt materials. However, the effect of fiber characteristic parameters (length, type, etc.) on the function of asphalt mortar is still lack of understanding. Therefore, a systematical experimental plan was conducted to evaluate the effects of the selected parameters of filler-binder ratio, fiber type, fiber content and fiber length on the rheological properties of asphalt mortar, including five filler-binder ratios (0.6, 0.8, 1.0, 1.2 and 1.4), four fiber types (three chopped basalt fibers with different coating agents named A, B and C and one flocculent basalt fiber), five fiber contents (1%, 2%, 3%, 4% and 5%) and three fiber lengths (6 mm, 9 mm, 15 mm). Then, Dynamic Shear Rheological (DSR) tests and Bending Beam Rheological (BBR) tests were employed to evaluate the rheological behavior of each asphalt mortar. The corresponding reinforcing mechanism was subsequently analyzed by Environmental Scanning Electron Microscope (ESEM) test. The results show that basalt fiber can obviously enhance the high-temperature rheological properties of asphalt mortars, while strengthen the stress dissipating ability at low temperatures to some extent. Besides, the fiber type, fiber content and fiber length all impact the rheological properties of asphalt mortars. The asphalt mortars with type A basalt fiber present the superior rheological performance at both high and low temperature, with the optimum fiber content of 2% and fiber length of 9 mm, respectively. The test results of ESEM reveals that basalt fiber shows spatial distribution in asphalt mortar, presenting the function of stabilization and reinforcement.

Copyright of Journal of Harbin Institute of Technology. Social Sciences Edition / Haerbin Gongye Daxue Xuebao. Shehui Kexue Ban is the property of Harbin Institute of Technology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

This study aims to comprehensively investigate the rejuvenation efficiency of various self-developed compound rejuvenators on the physical, mechanical, and aging properties of aged bitumen, asphalt mortar, and mixture. The results revealed that the restoration capacity of vacuum distilled-oil rejuvenators on high-and-low temperature performance-grade of aged bitumen is more significant. In contrast, an aromatic-oil based rejuvenator is good at enhancing low-temperature grade and aging resistance. Moreover, the temperature and time of the curing conditions for mixing recycling of asphalt mixture were optimized as 150 °C and 120 min. Furthermore, the sufficient anti-rutting, structural stability, and moisture resistance of recycled asphalt mixture affirmed the rejuvenation efficiency of compound rejuvenators. [ABSTRACT FROM AUTHOR]

An adequate moisture resistance is a key element to guarantee the durability of asphalt materials. This paper identifies the influence of filler typology and bitumen content on the mechanical response of asphalt mortars before and after water action. Two fillers were evaluated: Portland cement and Calcium carbonate, along with different contents of a penetration bitumen (B35/50). Stiffness, ductility, and fatigue were evaluated through a new protocol for asphalt mortar samples using a 3-point-bending test on DMA (Dynamic Mechanical Analyzer). The use of Portland cement presents higher stiffness, lower ductility, and improved fatigue and water resistance compared to Calcium carbonate. It is also possible to optimize bitumen content based on fatigue results. Content beyond the optimal reduce variations after water action but compromise fatigue resistance. Lower content leads to a poorer performance in both terms. This methodology enables asphalt mortar characterisation as a tool to optimise the design of asphalt materials.

The distribution characteristics of asphalt and cement mortar play a crucial role in determining the cracking resistance of semi-flexible pavements (SFP). In this study, digital image processing technology was utilized to quantify the thickness distribution of asphalt and cement mortar within SFP, and a parallel line segmentation method was employed to characterize the random distribution of mortar thickness (RDMT) of asphalt and cement mortar. Variance, coefficient of variation (COV), and interquartile range were proposed to characterize RDMT, examining the effects of air voids (AV) content, nominal maximum aggregate size (NMAS), and compaction method on RDMT, and its variation along the specimen height. Semi-circular bending test was conducted to evaluated the cracking resistance of SFP, exploring the relationship between RDMT and cracking resistance. Results indicate that parallel line segmentation method with 36 parts and 25 parts is recommended to characterize the RDMT of asphalt and cement mortar, respectively. An increase in AV content led to a higher RDMT for asphalt mortar but a lower RDMT for cement mortar. Conversely, as NMAS increased, the average thickness of asphalt and cement mortar increased, while the RDMT of asphalt mortar decreased and that of cement mortar increased. RDMT of asphalt and cement mortar is higher under Superpave gyration compaction method compared to the Marshall compaction method. Additionally, RDMT increased from the top to the bottom of the specimen height. Based on the RDMT, a random distribution index (RDI) was proposed, which exhibited a strong linear relationship with the cracking resistance of SFP. When the RDI decreased by 44.4 %, the corresponding cracking resistance of SFP increased by 84.0 %. Improving the distribution of asphalt and cement mortar could enhance the cracking resistance of SFP. • RDMT of asphalt and cement mortar in semi-flexible pavement was characterized. • Effects of AV content, NMAS, and compaction method on the RDMT of asphalt and cement mortar were investigated. • Relationships between cracking resistance of SFP and RDMT of asphalt and cement mortar were firstly investigated. [ABSTRACT FROM AUTHOR]

• Combining indoor experiments and numerical simulation results, the macro-fracture behavior and meso -fracture process of the asphalt mortar is revealed from macroscopic and mesoscopic perspectives. • Revealing the influence of crack deflection angle and crack length on the loading characteristics of cracks and facture behavior. • The fracture mode and the stress field at the crack tip is identified by using the FISH programming subroutine. Asphalt mortar is the base material used in asphalt concrete, and its mechanical properties directly affect those of the prepared asphalt concrete. An analysis of the loading response characteristics of cracks in asphalt mortar under low-temperature conditions can help reveal the interaction effect of multiple cracks in asphalt concrete and the influence mechanism of aggregates on the crack propagation and evolution behaviors. In this study, various forms of pre-cracks were generated in asphalt mortar specimens using the water jet cutting technology. Combined with the discrete element method (DEM), an indirect tensile (IDT) test and a virtual IDT test were conducted to analyze the effects of the crack deflection angle (β) and crack length (r) on the crack propagation behavior from macro- and meso -perspectives. The main results showed that: (1) Changes in the crack shape parameters (β and r) not only induced multiple branch cracks in the asphalt mortar but also led to the development of II Mode fractures; (2) With the increase in the crack shape parameters, the low-temperature crack resistance of the asphalt mortar decreased, with β having a greater effect on the crack propagation behavior than r ; (3) At the mesoscale, with the increase in the crack shape parameters, there was a gradual transformation of the fracture mode from I Mode to II Mode, and the crack propagation process accelerated, resulting in a significant decrease in the low-temperature crack resistance at the macroscale. The research results establish a theoretical foundation for revealing the characteristics of multi-crack propagation in asphalt concrete under environmental influences, and offer technical support for pavement crack repair and maintenance. [ABSTRACT FROM AUTHOR]

Basalt fiber has been shown to significantly improve the performance of asphalt mixtures and extend the lifespan of roads. However, more research is needed to investigate the characteristic parameters of basalt fiber when used in asphalt mortar and asphalt mixture. In order to enhance the reinforcing effect of basalt fiber on asphalt mixture and understand how it works, this study examines the properties of asphalt mortar mixed with basalt fiber with different characteristic parameters. Nine types of basalt fibers with varying characteristic parameters were selected for this work, including three lengths (3 mm, 6 mm, 12 mm) and three diameters (7 μm, 16 μm, 25 μm). The properties of asphalt mortar mixed with basalt fiber with different characteristic parameters were tested. High-temperature properties were characterized using the ZSV and MSCR tests; medium-temperature properties were characterized using the LAS test; low-temperature properties were characterized using the BBR and direct tensile tests. In addition, the effects of fiber characteristics on the viscosity, structural integrity and interfacial properties of asphalt mortar were analyzed through the bond strength test, Rigden porosity test and fiber monofilament drawing test. The results demonstrate that basalt fiber can improve high-temperature properties significantly in asphalt mortar while being greatly influenced by its characteristic parameters. Specifically, fibers with a length of 6 mm and a diameter of 7 μm exhibit superior reinforcement effects. Fatigue life results indicate that basalt fiber enhances fatigue resistance in asphalt mortar as well; furthermore, the influence exerted by fiber characteristic parameters aligns consistently with that observed for high-temperature performance. Although the BBR test results indicate that fiber incorporation has minimal impact on its enhancement, the direct tensile test results demonstrate a significant improvement in the toughness of asphalt mortar due to fiber reinforcement. The addition of basalt fiber enhances the bond strength of asphalt mortar. According to Einstein viscosity formula, the viscosity of asphalt mortar decreases with shorter fiber lengths and larger diameters. Incorporating basalt fiber can enhance the proportion and strength of structural asphalt in asphalt mortar. When comparing fibers with equal diameter or length, an increase in either parameter initially improves the strength of structural asphalt but eventually leads to a decline. Results from monofilament fiber drawing tests and theoretical critical embedding length confirm that a 6 mm fiber length is most beneficial for enhancing the performance of asphalt mortar. Basalt fiber exhibits significant potential for improving various properties of asphalt mortar and provides a favorable reference for optimizing the selection of basalt fiber. [Display omitted] • The synergistic effect and mechanism of basalt fiber (BF) and asphalt mortar with different characteristic parameters were studied. • The properties of basalt fiber and asphalt mortar with different characteristic parameters under multiple temperature fields are comprehensively characterized. • Einstein viscosity, structural asphalt and interfacial properties were used to study the effects of fiber characteristic parameters on the properties of asphalt mortar. • Basalt fiber, especially fiber with reasonable characteristic parameters, is the key to further improving the performance of asphalt mortar. [ABSTRACT FROM AUTHOR]

In order to analyze the high and low temperature performance of rice straw fiber asphalt mortar and the strengthening mechanism of rice straw fiber. Firsdy, the effects of fiber on shear resistance and high and low temperature rheological properties of asphalt mortar were investigated by cone penetration test, dynamic shear rheological test and bending beam rheological kst. Then, infrared spectroscopy was used to analyze the bond interaction between rice straw fiber and asphalt, and scanning electron microscopy test was used to reveal the mechanism of fiber in asphalt from a micro perspective. The results show that rice straw fiber can significantly improve the high temperature deformation resistance of asphalt mortar. But the addition of rice straw fiber will adversely affect the low temperature performance of asphalt mortar. The recommended optimum content of fiber in asphalt mortar is 2% 〜3%. There is no new characteristic peak in the infrared spectrum of asphalt mortar after the addition of rice straw fiber. The bonding action between rice straw fiber and asphalt is mainly physical action. The large surface roughness of rice straw fiber determines the good adsorption capacity of fiber to asphalt, which is conducive to increasing the adhesion of asphalt. The fiber lengthratio is large, which is easy to overlap with each other, and restricts the propagation of cracks, thereby enhancing the crack resistance of asphalt mortar. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Materials Science & Engineering (1673-2812) is the property of Journal of Materials Science & Engineering Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The use of steel slag powder instead of filler to prepare asphalt mortar was beneficial to realize the effective utilization of steel slag and improve the performance of asphalt concrete. Nevertheless, the anti-aging properties of steel-slag powder–asphalt mortar need to be further enhanced. This study used antioxidants and UV absorbers in steel-slag powder–asphalt mortar to simultaneously improve its thermal-oxidation and UV-aging properties. The dosage of modifier was optimized by second-generation non-inferior sorting genetic algorithm. Fourier-Transform Infrared Spectroscopy, a dynamic shear rheometer and the heavy-metal-ion-leaching test were used to evaluate the characteristic functional groups, rheological properties and heavy-metal-toxicity characteristics of the steel-slag-powder-modified asphalt mortar, respectively. The results showed that there was a significant correlation between the amount of modifier and G*, δ, and the softening point. When the first peak appeared for G*, δ, and the softening point, the corresponding dosages of x1 were 2.15%, 1.0%, and 1.1%, respectively, while the corresponding dosage of x2 were 0.25%, 0.76%, and 0.38%, respectively. The optimal value of the modifier dosage x1 was 1.2% and x2 was 0.5% after weighing by the NSGA-II algorithm. The asphalt had a certain physical solid-sealing effect on the release of heavy-metal ions in the steel-slag powder. In addition, the asphalt structure was changed under the synergistic effect of oxygen and ultraviolet rays. Therefore, the risk of leaching heavy-metal ions was increased with the inferior asphalt-coating performance on the steel-slag powder. [ABSTRACT FROM AUTHOR]

Asphalt mortar is a typical temperature-sensitive material that plays a crucial role in the performance of asphalt mixture. This study evaluates the high- and low-temperature performance of asphalt mortar based on the dynamic mechanical analysis (DMA) method. Temperature-sweep tests of asphalt mortars were conducted using the DMA method under fixed strain level, frequency, and heating rate conditions. The dynamic mechanical response curves, characteristic temperature, and other indices were obtained and used to investigate the high- and low-temperature performance of asphalt mortar. The results showed that the phase transition temperatures T1, T0, and Tg can be used to evaluate the low-temperature performance of asphalt mortar. Additionally, they had a good linear relationship, and the evaluation results were consistent. Meanwhile, T2, E60, and tan(δ)max indicators can effectively evaluate the high-temperature performance of asphalt mortar. Asphalt plays a key role in the performance of asphalt mortar. Mortars with neat asphalt A70 and modified asphalt AR had the worst and best high- and low-temperature performances, respectively. Furthermore, the finer gradation improved the low-temperature performance of asphalt mortar, while the coarser gradation improved the high-temperature properties of modified asphalt mortars but had the opposite effect on neat asphalt A70. [ABSTRACT FROM AUTHOR]

This article presents a new methodology of analysis based on a fast-running experimental procedure to characterise the mechanical response of asphalt mortars in terms of stiffness, ductility, and fatigue resistance. This was achieved using the DMA (Dynamic Mechanical Analyser) three-point bending configuration. The study was carried out by considering the employment of different types of fillers such cement and CaCO3 and different types of binders such as conventional asphalt binder (B35/50) or modifided polymer-modified bitumen (PMB 25/55–65). From the results of this study, the filler was found to have a greater influence on the stiffness and ductility of the asphalt material, while bitumen had a higher effect on the fatigue life of the asphalt mortar. Fatigue life was observed to increase with the use of a polymer-modified binder, while a lower degree of permanent deformation and higher bearing capacity achieved by the use of cement instead of calcium carbonate as active fillers. [ABSTRACT FROM AUTHOR]

The mechanical performance of asphalt mixtures with high air void content – like Permeable Friction Courses (PFC) – is significantly affected by climate-related processes. Previous studies have demonstrated that ravelling (i.e. the loss of aggregates from the surface of the PFC) is related to the quality of the stone-on-stone contacts within the microstructure of these mixtures. Since the material located at these contacts is asphalt mortar, the durability of the mixtures strongly depends on the mechanical properties of this phase. This paper evaluates, for the first time, the coupled effects of ageing and moisture on the mechanical and fracture properties of the asphalt mortar of a typical PFC. The climatic conditioning processes included short and long-term ageing and dry-wet-dry moisture vapour cycles. The linear viscoelastic and fracture properties of the PFC mortar specimens were characterised using Dynamic Mechanical Analyser (DMA) and Semi-Circular Bending (SCB) tests. The results showed that ageing impacted the dynamic modulus of the mortar, while moisture had a negligible effect on this property. Also, the coupled effects of long-term ageing and moisture cycles reduced the fracture energy and other fracture parameters of the mortar between 2 and 10 times with respect to the short-term ageing condition in dry state. [ABSTRACT FROM AUTHOR]

The film thickness of asphalt mortar, which is a mix of binder and fine mineral aggregates, has been considered as an important indicator for assessing the durability of asphalt mixture. This study proposes a novel method to characterise distribution of mortar film thickness in asphalt mixture through image processing techniques. Four asphalt mixtures with unmodified and modified binders were produced at various compaction temperatures in the laboratory. Their internal images were scanned and analysed. The values of mortar film thickness along the boundary of each aggregate in the scanned image were measured. And their mean value (Tm) and standard deviation (SDt) were calculated for characterising the distribution of mortar film thickness. The results indicate that both binder modification and compaction temperature have significant effects on the mortar film distribution. Furthermore, the proposed parameters were employed for understanding the correlation between the mortar film thickness and mixture cracking resistance. The flexibility index of short-term and long-term aged mixtures were measured and correlated with the mortar film parameters. The findings show that asphalt mixture with a lower mortar film thickness and a wider distribution is more sensitive to oxidative aging, which may result in a dramatic decrease of mixture's resistance to cracking. [ABSTRACT FROM AUTHOR]