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In order to investigate the feasibility of applying solidified shield muck in road construction, the shield muck from Nanjing Metro was taken as the research object, and the green polymer composite curing agent developed independently was used to solidify the shield muck. The impact of the curing agent dosage and maintenance age on the road performance indicators of the shield muck was analysed using various tests-unconfined compressive strength, direct shear test, California bearing ratio (CBR), resilient modules, and freeze-thaw cycle test. In addition, the micro-characteristics and solidification mechanism of the solidified soil were investigated by scanning electron microscope and X-ray diffraction. The results indicate that the composite curing agent can effectively improve the strength of solidified muck, and with the increase of curing agent dosage and maintenance age, the strength of solidified muck also increases. The CBR and resilient modulus of solidified shield muck substantially improve as the dosage of the curing agent elevates, and the solidified soil can well meet the requirements of the Specifications for Design of Highway Subgrades ( JTG D30— 2015) and Specifications for Design of Highway Asphalt Pavement ( JTG D50—2017). The freeze-thaw resistance of shield muck is poor, while it can be effectively improved after curing treatment. The strength loss and mass loss of solidified soil are less than 20% and 1% respectively. The anti-freezing performance indicators meet the requirements of the specification. After the curing agent has been added to the soil body, the polymer components will absorb water and dissolve, creating a static chelating effect with the mineral ions in the soil, initially reducing the water content of soil and promoting the agglomeration between the soil particles. Meanwhile, the other components of the curing agent generate hydration reaction to form hydrated calcium silicate gel, ettringite and other substances to fill the internal pores of soil, making the soil structure denser and greatly improving the strength. [ABSTRACT FROM AUTHOR]

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The impact of ice and snow in seasonally frozen regions has led to a significant decline in the flatness and skid resistance of highway pavements, creating severe traffic safety hazards. With economic development driving the transition from road construction to maintenance, this study proposes enhancing Ultra-Thin Wearing Course (UTWC) maintenance materials with anti-icing performance and snow-melting properties. The study first employed the Marshall mix design method to develop gradations for two common types of UTWC asphalt mixtures: the dense-graded GT-8 and the open-graded NovaChip® Type-B. Using the volume substitution method, aggregates were replaced with equivalent volumes of ceramic grains. The optimal asphalt–aggregate ratios for the mixtures with varying ceramic grain contents were determined, and the influence of ceramic grains content on the asphalt–aggregate ratio was analyzed. The results indicate that the optimal asphalt–aggregate ratio increases with higher ceramic grains content. Subsequently, the high-temperature performance, low-temperature performance, and water stability of UTWC with varying ceramic grain contents were evaluated. Overall, NovaChip® gradation mixtures demonstrated superior road performance compared to GT-8 gradation mixtures. Moreover, an increase in ceramic grains content enhanced the high-temperature performance of UTWC but moderately reduced its low-temperature performance and water stability. Finally, the effects of different ceramic grain contents and snowmelt agent types on the anti-icing and snowmelt properties of UTWC were examined. The results revealed that higher ceramic grains content improved snowmelt effectiveness. Considering the road performance of the specimens, a ceramic grains content of 40% was recommended. Furthermore, calcium chloride (CaCl2) exhibited superior anti-icing performance compared to other snowmelt agents. [ABSTRACT FROM AUTHOR]

This study investigates the performance enhancement of asphalt and its mixtures through modification with varying contents of styrene–butadiene–styrene (SBS) and rock asphalt (RA). A series of laboratory tests were conducted to comprehensively evaluate the effects of SBS and RA modification. The results demonstrated that SBS significantly improves elasticity, low-temperature ductility, and resistance to fatigue and rutting, while RA enhances high-temperature stability, water stability, and stripping resistance. The synergistic effects of SBS and RA were evident, with the 4% SBS/10% RA mixture achieving the best comprehensive performance, which was characterized by improved high-temperature stability, low-temperature performance, and durability. Conversely, 15% RA content was found to reduce low-temperature flexibility and fatigue performance. A radar chart-based evaluation further confirmed the optimal performance of the 4% SBS/10% RA combination. These findings provide valuable guidance for selecting appropriate SBS and RA proportions tailored to specific performance requirements in asphalt pavement applications. [ABSTRACT FROM AUTHOR]

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Copyright of Railway Construction Technology is the property of Railway Construction Technology 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 explore the influence of the polyurethane blending ratio on the micro-characteristics of polyurethane-modified asphalt, three samples of the modified asphalt with different blending ratios (40%, 50%, and 60%) were prepared. Fourier transform infrared spectroscopy (FTIR), atomic force microscopy (AFM), and scanning electron microscopy (SEM) were employed to elucidate the modification mechanism of polyurethane-modified asphalt. To investigate how the preparation method affects the performance of polyurethane-modified asphalt mixtures, two different preparation methods, namely internal blending and external blending, were adopted. The road performance of the polyurethane-modified asphalt mixtures was evaluated through the utilization of rutting tests, low-temperature trabecular bending tests, and freeze–thaw splitting tests. The FTIR test results indicate that during the modification of polyurethane, there is a change in both the intensity and position of the absorption peak, which affects the local arrangement of the molecular structure. Upon reaching a polyurethane blending ratio of 50%, a cross-linked network structure that is similar to polyurethane is formed. The results of the AFM test demonstrate that an increase in polyurethane content results in a corresponding increase in surface roughness. At a polyurethane content of 50%, the curing reaction is most effective, which is beneficial for enhancing the bonding performance between the asphalt and the aggregate, thereby enhancing the overall water stability of the mixture. The results of the scanning electron microscopy (SEM) tests indicate that the microstructure is more stable when the polyurethane content is 50%. The results of the performance test of the polyurethane-modified asphalt mixture indicate that the dynamic stability of the polyurethane-modified asphalt mixture is approximately four times that of the SBS-modified asphalt mixture. The flexural tensile strength and maximum flexural strain of the polyurethane-modified asphalt mixture are, respectively, 1.5 and 3.2 times those of the SBS-modified asphalt mixture, indicating that its anti-deformation ability is stronger in a low-temperature environment, and it is found that the low-temperature performance of the mixture prepared with the internal blending method is better than that with the external blending method. The splitting strength of the polyurethane asphalt mixture before and after freezing and thawing is greater than that of an SBS asphalt mixture: before freezing and thawing, by about 3.8 times; after freezing and thawing, by about 3 times. Although the freezing and thawing of the polyurethane mixture has damage, it still meets the requirements of the use of pavement materials. It can be observed that the incorporation of polyurethane alters the internal structure of the asphalt, which markedly enhances the properties of the asphalt mixture and offers a novel perspective on the development of modified asphalt materials. [ABSTRACT FROM AUTHOR]

This is an article in the field of ceramics and composites. In order to investigate the basic road performance of mica powder modified asphalt mixture, modified asphalt with 0%, 3%, 5%, 7%, 9%, and 11% content was prepared. Through rotational viscosity test, penetration test and Fourier infrared spectroscopy test, the performance of mica powder modified asphalt was analyzed. AC-20 mica powder modified asphalt mixture was prepared to explore its road performance and the influence law of mica powder dimension content on asphalt mixture road performance was determined by grey correlation analysis. The test results show that the addition of mica powder can reduce the temperature sensitivity of the asphalt, and the addition of mica powder to the asphalt only causes physical blending. As the content of mica powder increases, the improvement effect of mica powder on asphalt pavement performance first increases and then decreases. When the content of mica powder is 7%, the road performance of mica powder modified asphalt mixture reaches the best. The grey correlation analysis shows that the influence degrees of mica powder dosage on road performance indicators are high temperature stability > moisture stability > low temperature crack resistance．

Micro-nano rubber asphalt was prepared by high-temperature and high-speed shearing with micro-nano degraded rubber powder as raw material, and the micromorphology of micro-nano degraded rubber powder and miscible process of micro-nano rubber rubber and substrate asphalt were investigated by scanning electron microscopy, transmission electron microscopy and X-ray photoelectron spectrometer, and the road performance of micro-nano rubber asphalt mixture including water stability, temperature stability and cracking failure resistance were studied by the design of asphalt aggregate ratio. In addition, the application effect of micro-nano rubber asphalt mixture in practical road engineering was further evaluated. The results showed that mass fraction of sol in degraded rubber in which the size of dissociated carbon black was about 200 nm reached 65.7%, and the interaction of sulfur cross-linked bond between degraded rubber and asphalt appeared during the miscible process; the micro-nano rubber asphalt mixture showed excellent water stability, high- and low-temperature stability and cracking failure resistance; the key technical indexes of the upper layer and the lower layer in full-depth rubber asphalt pavement of test section of Jiuquan-Jiayuguan ring expressway prepared by using micro-nano rubber asphalt mixture in Gansu province all complied with the specifications and design requirements.

Waste plastics and rubber have always posed a threat to the environment and a great challenge for disposal. The use of these two waste materials as modifiers for road asphalt provides new road asphalt binders and at the same time provides a new way for waste material resource treatment. Rubber-modified asphalt and plastic-modified asphalt have received widespread attention due to their green and low-carbon characteristics and some performance advantages, but there are still some performance shortcomings that hinder their promotion and application. In order to continue to explore the application of waste materials in the field of road engineering, combined with the performance advantages of both, many scholars began to study the rubber-plastic composite modified asphalt (RPCMA). Therefore, this paper reviewed the different types of waste rubber and plastic, the comprehensive performance of different types of asphalt and its mixture performance, analyzed the modification mechanism of rubber-plastic composite modified asphalt and its performance changes. The results show that rubber-plastic composite modified asphalt is mostly prepared by directly adding modified materials. However, the pretreatment or melt granulation of rubber and plastic will make the performance of rubber-plastic modified asphalt has improved. There is a mutual promotion mechanism between rubber and plastic in asphalt, which makes the performance of rubber-plastic modified asphalt better than that of asphalt obtained by a single modification method (rubber modified asphalt or plastic modified asphalt). In some properties, it can be close to the commercial SBS modified asphalt. The performance of rubber and plastic composite modified asphalt at high temperature has been generally recognized by researchers, but its low-temperature performance is still controversial. Therefore, it is recommended to apply in high-temperature areas. Future work should focus on the development of composite modifiers with stable performance, low cost and ease of use, standardization of modification processes, improvement of low-temperature performance, and monitoring of road performance and environmental impact.

The pavement base and subbase are the main load-bearing structures of asphalt pavement, and their materials need to have sufficient bearing capacity. Therefore, in the development of LSAM-50 mixtures with higher bearing capacity, after significant research and engineering practice, conventional particle size asphalt mixtures have formed their own excellent mineral gradation and have been incorporated into relevant specifications, while LSAM-50 mixtures, including mineral gradation, have not been involved in related research and engineering applications. According to the strength composition mechanism of asphalt mixtures, under the same circumstances of asphalt, due to the large nominal maximum particle size of LSAM-50 and the small amount of asphalt used, the strength of mineral grading is more important than that of asphalt, which is one of the key issues to be solved in the research of LSAM-50 mixtures. This study aims to enhance the road performance of asphalt mixtures with a maximum nominal particle size of 50 mm (LSAM-50). The variation of void ratios in coarse aggregate skeletons was investigated when aggregates of 37.5–53 mm (designated as D1), 19–37.5 mm (designated as D2), and 9.5–19 mm (designated as D3) were mixed in different proportions. Meanwhile, the effects of fine aggregate gradation on the strength of asphalt mortar and the influence of the ratio of coarse to fine aggregates on the mechanical strength of LSAM-50 were examined. A densely graded structure with strong interlocking for LSAM-50 was proposed, and its road performance was verified. The results indicate that when the ratio of D1, D2, and D3 is 5:2:3, the void ratio of the mixed coarse aggregate is minimized. When the decrement factor i is 0.75, the compressive strength and splitting strength of asphalt mortar reach their maxima. Compared with the densely graded asphalt-stabilized aggregate mixture (ATB-30) with a maximum nominal particle size of 37.5 mm, the dynamic stability of LSAM-50 with the proposed gradation is increased by 400%, the low-temperature bending strain by 3%, the SCB bending strength by 47%, and the residual SCB strength by 90%. [ABSTRACT FROM AUTHOR]

Owing to its good performance and quick construction, micro-surfacing is frequently employed in the prevention and treatment of pavement diseases. However, the shortcomings of the current design methods and the noise problems have not been resolved. Two ways of optimising gradation and adding additives were used to reduce the noise and enhance the performance of micro-surfacing. The gradation of the micro-surfacing was investigated based on fractal theory and the optimum gradation range was determined. The results showed that adding more fibre to micro-surfacing improves its resistance to rutting, wear, water damage and cracking. The anti-skid performance of rubber powder-fibre micro-surfacing (RFMS) falls as the asphalt aggregate ratio rises, but wear resistance and water damage resistance rise and rutting resistance and fracture resistance increase initially before declining. The best mix proportion of RFMS is determined based on the overall mass of aggregate and each component is as follows: 1.5% cement (PO42.5), 3% rubber powder (40 mesh) and 0.2–0.25% polypropylene monofilament fibre (6 mm). RFMS can reduce pavement noise while maintaining good anti-skid performance. The study is an important supplement to the research on micro-surfacing and its noise reduction. [ABSTRACT FROM AUTHOR]

This study investigates the mechanical response and road performance of waterproof adhesive layers on concrete bridge decks through numerical simulations and laboratory tests. A finite element model examined mechanical responses under various parameters. Composite samples made of waterborne epoxy–polyurethane asphalt (WEPA) were prepared and tested, analyzing factors like spray volume, curing time, shear angle, and shear rate through pull-out and shear tests. Shear fatigue characteristics of WEPA were also evaluated. Results show that maximum shear stress in the waterproof layer is positively correlated with pavement modulus, overload coefficient, vehicle driving state, deck slope, and interlayer contact, but negatively correlated with vehicle speed. The most unfavorable condition corresponds to a shear angle of 30.6°. Tests indicate that the optimal WEPA spray volume is 1.1 kg/m2 with a curing time of approximately 24 hours. Shear strength increases with shear rate, optimal at 10 mm/min. Shear fatigue performance is significantly affected by temperature changes. These findings are important for enhancing the road performance of waterproof adhesive layers and extending the service life of concrete bridge deck pavements. [ABSTRACT FROM AUTHOR]

Thermoplastic polyurethane (TPU) is an excellent asphalt modifier, which is consisted of hard and soft segments in the TPU molecular chain. In this paper, The conventional road performances (high and low temperature performance, water stability, fatigue performance and aging resistance) of TPU modified asphalt mixture (TPU-AM) with different hard segment content were evaluated. The results proved that the hard segment of TPU can effectively improve the high temperature performance of asphalt. Compared with TPU-AM with high hard segment content, using TPU with low hard segment content as modifier, the low temperature flexibility and fatigue resistance of TPU-AM are significantly improved. TPU-AM with hard segment content of 40% has excellent high temperature performance, while the TPU-AM with hard segment content of 10% has the best fatigue ability and low temperature performance. The water stability of TPU-AM is obviously stronger than that of base asphalt mixture, although the content of TPU hard segment has little influence on the water stability of TPU-AM. The aging results show that TPU-AM has the best aging resistance when the hard segment content is 30%. Based on the above analysis, the high performance of TPU-AM can be designed by changing the hard segment content. [ABSTRACT FROM AUTHOR]

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Copyright of China Plastics / Zhongguo Suliao is the property of Journal Office of CHINA PLASTICS 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.)

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.)

Copyright of Experimental Technology & Management is the property of Experimental Technology & Management 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 investigate the feasibility of composite modification techniques in improving the performance of recycled asphalt mixtures, in this study, the high-viscosity agent (HVA) and crumb-rubber materials (CRM) were used to modify asphalt with a styrene-butadiene-styrene block copolymer (SBS), in order to prepare SBS-HVA and SBS-CRM composite-modified asphalts. The virgin asphalt mixtures, as well as three asphalt types of recycled asphalt mixtures with 50% reclaimed asphalt pavement (RAP) content, were designed. The optimal asphalt content of the four types of asphalt mixtures was analyzed, and the rutting test, the asphalt bond strength test, the moisture-induced sensitivity test, and the low-temperature cracking resistance test were conducted to investigate the performance of the four types of asphalt mixtures. The results showed that the higher the asphalt kinematic viscosity, the higher the optimum asphalt content of the asphalt mixtures under the same air voids. HVA significantly improves the adhesion between SBS-modified asphalt and aggregate under dry conditions, while SBS-CRM composite-modified asphalt performs similarly to SBS-modified asphalt. Before and after water immersion, the degree of pull-out strength decay between the asphalts and aggregates follows the sequence of SBS-CRM- > SBS- > SBS-HVA-modified asphalts. Additionally, the residual pull-out work follows the sequence of SBS-HVA- > SBS-CRM- > SBS-modified asphalt. SBS-CRM composite-modified asphalt can significantly improve the moisture sensitivity of recycled asphalt mixtures, as well as low-temperature cracking resistance, while SBS-CRM composite-modified asphalt only improves the low-temperature cracking resistance of recycled asphalt mixtures, and does not improve the moisture sensitivity. Based on the results, it is recommended to select the appropriate composite modification method based on the climate and loading conditions, to maximize the value of asphalt, and to achieve sustainable and durable pavement. [ABSTRACT FROM AUTHOR]

In order to reduce the amount of diluent in a diluted asphalt mixture, this study developed a cold patch asphalt (CPA) for repairing pavement potholes by using a mixture of treated biodiesel and diesel as the diluent. The effects of biodiesel on the performance of the cold patch asphalt mixture (CPAM) during the construction process were investigated through Brookfield rotational viscosity tests, adhesion tests, and FTIR (Fourier transform infrared spectroscopy) analyses. At the same time, the effect of biodiesel on the performance of the CPAM was analyzed by combining the strength growth test, rutting test, and water-soaked Marshall test of CPAMs. The test results show that the construction performance of the CPAM can be significantly improved by adding pretreated biodiesel. Under the same amount of diluent, the strength and high-temperature performance of the asphalt mixture diluted with biodiesel were significantly improved compared to that with diesel as the diluent. The optimal high-temperature performance reached 9027 (times/mm), representing an approximate increase of 94.7% compared to 4636 (times/mm) when only diesel was used as the diluent. When the biodiesel content increased from 10% to 40%, the residue stability improved from 85.9% to 91.3%. The corresponding 0.5 h Marshall stability increased from 5.59 kN to 8.1 kN, while the 48 h Marshall stability rose from 4.8 kN to 7.39 kN. All tests met the requirements for hot mix asphalt. [ABSTRACT FROM AUTHOR]

SBS-modified asphalt produces a large number of hazardous fumes in the preparation process, which severely endangers health and causes environmental pollution. This paper details the design of a fume generation and collection device for asphalt and proposed a comprehensive method for analyzing fume composition. Two deodorants were incorporated into SBS-modified asphalt to mitigate the hazards of the original hazardous emissions. Then, ultraviolet–visible spectrophotometry, gas chromatography–mass spectrometry, and Fourier-transform infrared spectroscopy were combined to analyze the main component differences between asphalt fumes before and after adding deodorant, and to specify the mechanism of action of deodorants on hazardous fumes and SBS-modified asphalt. Finally, the road performance, including the physical and rheological properties of SBS-modified asphalt blended with deodorant, was evaluated. The results indicated that both deodorizers were effective in reducing the emission of hazardous substances in the fumes of SBS-modified asphalt, and no new hazardous substances were generated. Under hot mixing conditions, the addition of 0.3% of deodorant A (high boiling point ester) was effective in reducing the emission of volatile organic compounds (VOCs) by up to 41.7%, while the reduction in benzene congeners reached at least 50%. On the other hand, 1% of deodorant B (silica–magnesium compounds) reduced the emissions of VOCs and benzene congeners by 36% and 20–42%, respectively, under the same conditions. Furthermore, the addition of deodorant did not affect the original road performance, and even improved the rheological properties to a certain extent, which was conducive to the application of deodorant in pavement engineering. [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.)

Bio-oil as a substitute or modifier for petroleum asphalt has significant environmental, economic, and sustainable development implications. However, the insufficient high-temperature and anti-aging characteristics of bio-asphalt lead to the limited application of bio-oil in road engineering. In this study, the characteristics of bio-asphalt were reinforced by nano-Al2O3 and nano-SiO2. The nanomaterial-modified bio-asphalt was evaluated using basic characteristics, viscosity, and high- and low-temperature rheological characteristic tests. Meanwhile, the road behavior of nanomaterial-modified bio-asphalt mixtures was assessed. The test results demonstrated that incorporating bio-oil improved the low-temperature performance of PA. Compared with PA, BA's ductility was increased by 83.87%. Nano-Al2O3 and nano-SiO2 positively affected the bio-asphalt's temperature sensitivity and high-temperature and anti-aging characteristics but inhibited the low-temperature characteristics. Combining the results of the high- and low-temperature characteristics of nanomaterial-modified bio-asphalt, a nano-Al2O3 dosage between 4 and 6% or a nano-SiO2 dosage between 6 and 8% can realize the enhancement of high-temperature and anti-aging characteristics of bio-asphalt, and the low-temperature characteristics are better than those of petroleum asphalt. Meanwhile, the dynamic stability, crack resistance, and water loss resistance of the nanomaterial-modified bio-asphalt mixtures meet the specification requirements. The adjustable and designable high- and low-temperature characteristics of bio-asphalt can be realized by adjusting the dosage of nanomaterials. The application of bio-oil and nanomaterials promotes the resourceful utilization of waste and provides new possibilities for road engineering materials. [ABSTRACT FROM AUTHOR]

In order to promote the application of steel slag in road engineering and alleviate the problems of land occupation and environmental pollution caused by steel slag stockpiling, the physicochemical characteristics of steel slag during aging and the performance of steel slag asphalt mixtures were investigated. The morphological characteristics and mineral composition of steel slag before and after aging were investigated using particle size and shape and XRF(X-ray fluorescence spectroscopy) tests. Subsequently, asphalt mixtures were prepared using untreated steel slag, aged steel slag and basalt, and the volumetric expansion, water stability, high-temperature stability and low-temperature cracking resistance of the three asphalt mixtures were comparatively evaluated. In addition, the correlation between aggregate properties and mix performance was analysed by grey correlation method. The results show that the high roughness and angularity of steel slag make it an ideal substitute for natural aggregates such as basalt. However, the poor volume stability of unaged steel slag and its tendency to swell in contact with water resulted in its inability to meet the requirements for pavement use. It is worth noting that CaO and Fe2O3 contents are important factors affecting the volumetric stability of steel slag, and aging treatment can reduce these negative effects to a certain extent, thus improving the road performance of steel slag asphalt mixtures. Comprehensive analyses, aged steel slag asphalt mixture has better comprehensive road performance, and the secondary use of steel slag is of great significance to achieve sustainable development of road infrastructure. [ABSTRACT FROM AUTHOR]

In order to improve the road performance of asphalt pavement, polyurethane/nano-ZnO composite modified asphalt was prepared by polyurethane, nano-ZnO and matrix asphalt. Taking penetration, softening point, ductility and 135 ° viscosity as evaluation indexes, the influence of modifier on asphalt performance was studied, and the storage stability was evaluated by softening point difference. Three kinds of composite modified asphalt AC-13C mixture were prepared for rutting test, trabecular bending test and immersion Marshall test to study the performance of modified asphalt mixture. The results show that the incorporation of polyurethane and nano-ZnO can significantly improve the high and low temperature performance of the matrix asphalt, and the storage stability meets the requirements of the specification. The composite modified asphalt mixture can meet the road performance of asphalt pavement. The modified asphalt mixture with 5% polyurethane and 3% nano-ZnO content has the best effect on improving high temperature performance and water stability. Compared with the matrix asphalt mixture, the dynamic stability is increased by 2.32 times, the residual stability is increased by 9.0%, and the maximum flexural tensile strain (-10 °) is increased by 8.3%. Considering the improvement effect of road performance, it is recommended to use 5% polyurethane compound 3% nano-ZnO as the best content of composite modified asphalt and its mixture. [ABSTRACT FROM AUTHOR]

Liquid rubber (LR) has been proven to be a valuable asphalt modifier capable of addressing the existing deficiencies associated with crumb rubber–modified asphalt (CRMA), including poor workability and storage stability. Therefore, an accessible preparation method based on olefin metathesis was explored to produce optimal LR from crumb rubber (CR) in the laboratory. This research established the optimal laboratory preparation conditions for LR and investigated the performance of liquid rubber–modified asphalt (LRMA) mixture when used in pavement. A total of 32 LR samples were generated by olefin metathesis and physical swelling under various catalytic and swelling conditions. The physical properties, viscosity, and storage ability of LRMA were evaluated to select the optimal preparation parameters for LR. A comprehensive analysis was performed to compare the physicochemical characteristics of LR and the original CR through microscopic examinations with scanning electron microscopy (SEM), Fourier-transform infrared spectrometry (FTIR), and gel permeation chromatography (GPC). An in-depth evaluation assessed the stability at high temperatures, the properties at low temperatures, and the moisture stability of LRMA and CRMA mixtures. Experimental results showed that the optimal laboratory preparation conditions for LR were a catalyst dosage between 3‰ and 5‰, a catalytic duration of 48 h, a swelling temperature of 160°C, and a swelling time of 8 h. Moreover, LR possessed a smooth surface without rubber particles. The molecular weight and distribution of LR were considerably reduced compared with those of CR after olefin metathesis and physical swelling. The introduction of LR significantly enhanced the cracking resistance of the base asphalt mixture. However, the enhancement effect of LR on the base asphalt mixture to resist high-temperature rutting and moisture damage was inferior to that of CR. [ABSTRACT FROM AUTHOR]

Copyright of Fly Ash Comprehensive Utilization is the property of Hebei Fly Ash Comprehensive Utilization Magazine Co., Ltd. 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.)

Coffee grounds were thermally degraded to produce spent coffee grounds biochar (SBC), which was used for the bio-modification of asphalt. Rheological experiments and microscopic structure tests were conducted to investigate the effects of SBC on the high and low temperature rheological properties of asphalt and its modification mechanism. A 9% SBC content was selected to prepare asphalt mixtures, and their road performance was analyzed. The results showed that the irregular, rough, and porous structure of SBC could improve the high-temperature resistance to rutting and deformation of asphalt binder, and it was highly compatible with asphalt. The modification mechanism of SBC-modified asphalt was a physical filling effect rather than chemical modification. The road performance of asphalt mixtures showed that SBC could improve the resistance to water damage and high-temperature deformation of asphalt. Consistent with BBR rheological tests, SBC had a certain negative effect on the low-temperature performance of asphalt, but this effect was controllable. [ABSTRACT FROM AUTHOR]

As a nanomaterial, graphene can affect the microstructure and macroscopic properties of the material, and make the material have electrical conductivity and thermal conductivity. The application effect of graphene and its related nanomaterials in asphalt and its mixture is remarkable. The characteristics of Gr (graphene), GO (graphene oxide) and GNPs (graphene nanosheets) in asphalt and its mixtures were reviewed, including high temperature performance, low temperature performance, aging performance, water stability, electrical conductivity and thermal conductivity. It is pointed out that Gr, GO and GNPs can improve the performance of asphalt and asphalt mixture, and improve the high temperature rutting resistance, aging resistance and water damage resistance. At the same time, due to the excellent thermal conductivity and electrical conductivity of Gr, GO and GNPs, the resistivity of asphalt and mixture can be reduced and the thermal conductivity can be improved. Graphene can play a better role in the construction of intelligent roads such as snow melting, ice melting and self-sensing pavement. [ABSTRACT FROM AUTHOR]

To solve the problems on resource utilization and environmental pollution of waste concrete and waste polypropylene (PP) plastics, the recycling of them into asphalt pavement is a feasible approach. Considering the high melting temperature of waste PP, this study adopted a thermal-and-mechanochemical method to convert waste PP into high-performance warm-mix asphalt modifiers (PPMs) through the hybrid use of dicumyl peroxide (DCP), maleic anhydride (MAH), and epoxidized soybean oil (ESO) for preparing an asphalt mixture (RCAAM) containing recycled concrete aggregate (RCA). For the prepared RCAAM containing PPMs, the mixing temperature was about 30 °C lower than that of the hot-mix RCAAM containing untreated PP. Further, the high-temperature property, low-temperature crack resistance, moisture-induced damage resistance, and fatigue resistance of the RCAAM were characterized. The results indicated that the maximum flexural strain of the RCAAM increased by 7.8~21.4% after using PPMs, while the sectional fractures of the asphalt binder were reduced after damaging at low temperature. The use of ESO in PPMs can promote the cohesion enhancement of the asphalt binder and also improve the high-temperature deformation resistance and fatigue performance of the RCAAM. Notably, the warm-mix epoxidized PPMA mixture worked better close to the hot-mix untreated PPMA mixture, even after the mixing temperature was reduced by 30 °C. [ABSTRACT FROM AUTHOR]

Aqueous epoxy color coatings was modified by IIV absorbent. Through indoor accelerated aging simulation tests, FUR tests and SEM tests, the aging mechanism of coatings, the modification mechanism ami effect of ultraviolet absorbers were studied. And the road performance of the coating was tested under oomiitions of immersion, low temperature, high temperature, IIV aging, chemical oorrosion, an