A kind of neat asphalt and three kinds of diatomite asphalt are tested using differential scanning calorimetry（DSC）. The anti-cracking mechanism of diatomite asphalt is analyzed by DSC and the thermal stress restrai...A kind of neat asphalt and three kinds of diatomite asphalt are tested using differential scanning calorimetry（DSC）. The anti-cracking mechanism of diatomite asphalt is analyzed by DSC and the thermal stress restrained specimen test（TSRST） of the asphalt mixtures. The results show that the low temperature performance of diatomite asphalt is better than that of neat asphalt. The glass transition temperature can reflect the low temperature performance of the diatomite asphalt better and has a good relationship with breaking temperatures. Besides, the TSRST, the bending test, the compressing test and the contraction coefficient test are used to study the low temperature performance of the diatomite asphalt mixture. The results prove that the low temperature performance of the diatomite asphalt mixture is better than that of the neat asphalt mixture. The critical bending strain energy density and the compressing strain energy density of the diatomite asphalt mixture are greater than those of the neat asphalt mixture. After adding diatomite to the asphalt mixture, the contraction coefficient is reduced. Based on the above results, the anti-cracking mechanism of the diatomite asphalt mixture is analyzed from the angle of contraction performance and breaking energy.展开更多
The deoiled asphalt as the carbon source and the ferrocene as the metal source and the catalyst precursor were chosen to synthesize iron-containing carbon microparticles through co-carbonization at the temperature of ...The deoiled asphalt as the carbon source and the ferrocene as the metal source and the catalyst precursor were chosen to synthesize iron-containing carbon microparticles through co-carbonization at the temperature of about 450℃ for 3 h. The resulting products were treated at 2 000 ℃ for 2 h. All samples were examined by high resolution transmission electron microscopy （HRTEM） and X-ray diffraction （XRD）. The results show that the iron particles in the heat-treated material are completely coated by carbon. In addition to the fully filled carbon microparticles as well as hollow carbon ones, also form carbon fibers with hollow centers. The formation mechanism of the as-prepared products was discussed briefly.展开更多
Through scanning electron microscope （SEM）, spectral analysis, and component analysis tests, the interaction theory between asphalt and rubber was discussed. It is concluded that rubber powder become soft and bond t...Through scanning electron microscope （SEM）, spectral analysis, and component analysis tests, the interaction theory between asphalt and rubber was discussed. It is concluded that rubber powder become soft and bond together with each other after being mixed with asphalt. The asphalt changes from a smooth homogeneous matter to a continuous mixing system which is composed of rubber powder and asphalt. The interaction is mainly physical diffusion, but there are some chemical reactions in the process, especially at long reaction time.展开更多
In order to find a parameter as the evaluation index that can capture the effect of the interaction between asphalt and aggregate, the rheological properties of asphalt mastics using two kinds of asphalts and four kin...In order to find a parameter as the evaluation index that can capture the effect of the interaction between asphalt and aggregate, the rheological properties of asphalt mastics using two kinds of asphalts and four kinds of aggregates under different filler-asphalt ratios were measured by a dynamic shear rheometer （DSR）. Moreover, four rheological parameters of K.Ziegel-B, Luis Ibrarra-A, complex shear modulus ΔG＊and complex viscosity Δη＊ for evaluating the interaction ability were studied. Results indicate that all the four parameters can characterize the interaction ability of asphalt and aggregate correctly and feasibly. Through the comparison of sensitivities and physical meanings of the four parameters, K.Ziegel-B with high sensitivity and exact physical meaning is finally selected as the evaluation index for interaction ability of asphalt and aggregate.展开更多
With the rapid development of asphalt pavement technology,it has attracted considerable attention to improving the durability of asphalt pavement.An effective action is to use modified asphalt with high performance an...With the rapid development of asphalt pavement technology,it has attracted considerable attention to improving the durability of asphalt pavement.An effective action is to use modified asphalt with high performance and durability.Polyurethane(PU)has been used in asphalt pavement engineering to enhance the durability and service life of asphalt pavement because of its excellent high-temperature performance,toughness,wear resistance,aging resistance and oil resistance.However,PU modified asphalt technology is still in the exploratory stage.The preparation,modification mechanism and working performances of PU modified asphalt need to be further clarified.Therefore,this paper summarized the research progress of PU modified asphalt and its mixture.The composition of PU modified asphalt was introduced.The addition methods of PU materials and preparation process parameters of the PU modified asphalt were determined.The modification mechanism of PU on asphalt was discussed.The effects of polyurethane on asphalt were analyzed and the road performances of its mixture were evaluated.Finally,the development tendency towards PU modified asphalt and its mixture were forecasted.展开更多
Asphalt mixtures and cement concrete are an important material in the construction of roads,highways and buildings,and there has been a lot of research about the improvement of their performance.Among them,fibers are ...Asphalt mixtures and cement concrete are an important material in the construction of roads,highways and buildings,and there has been a lot of research about the improvement of their performance.Among them,fibers are commonly used in the construction industry because of their superior properties as reinforcing materials that can provide a proper interfacial action between the fibers and the substrate.This review classifies fibers into natural fibers,inorganic fibers and polymer fibers according to their sources and properties.It summarizes and compares the characteristics,modification methods,usage requirements and research status of each type of fiber in asphalt and cement construction materials,and analyzes the problems and challenges faced by fibers in their applications.The evaluation results show that various types of fibers can enhance the fracture resistance,tensile strength and rutting resistance of asphalt to a certain extent,improve the high temperature performance and viscoelasticity of asphalt,and have a certain effect on the fatigue resistance and road water resistance of asphalt mixes.The fibers also provide better tensile,compressive and abrasion resistance to cement concrete and improve the brittleness and crack resistance of ordinary cement.Besides,for some defects of various types of fibers in construction materials,such as biodegradability,dispersibility and surface inertness of fibers,the targeted modification of fibers is introduced based on physical and chemical modification methods to improve the performance impact of modified fibers in various conditions of application.展开更多
Within the past two decades or so, the asphalt paving industry has responded positively to increasing global concerns over shrinking natural resource reserves and worsening environmental conditions through the develop...Within the past two decades or so, the asphalt paving industry has responded positively to increasing global concerns over shrinking natural resource reserves and worsening environmental conditions through the development and deployment of warm-mix asphalt technologies. Such technologies make it possible to produce and place asphalt concrete at reduced temperatures compared to conventional hot-mix methods. Several studies have reported on the potential of warm-mix asphalt with regard to improved pavement performance, efficiency and environmental stewardship. This paper reviews several of those studies in the context of pavement sustainability. Overall, warm-mix asphalt provides substantial sustainability benefits similar to or, in some cases, better than conventional hot-mix asphalt. Sustainability benefits include lower energy use, reduced emissions, and potential for increased reclaimed asphalt pavement usage. Growth in utilization of warm-mix asphalt worldwide may, in the not-too-distant future, make the material the standard for asphalt paving. Regardless, there are concerns over some aspects of warm-mix asphalt such as lower resistance to fatigue cracking, rutting and potential water-susceptibility problems, particularly with mixes prepared with water-based technologies, which require further research to address.展开更多
Rutting of asphalt pavement occurs earlier and is more serious under the increasingly heavy traffic load conditions that can be found in subtropical monsoon climate regions.High modulus asphalt concrete(HMAC)with exce...Rutting of asphalt pavement occurs earlier and is more serious under the increasingly heavy traffic load conditions that can be found in subtropical monsoon climate regions.High modulus asphalt concrete(HMAC)with excellent anti-rutting and anti-fatigue properties is generally used to mitigate this issue.Given the relatively high cost of the additives used in this type of asphalt,in this study the feasibility of using recycled asphalt mixture(RAP)and Trinidad lake asphalt(TLA)for the preparation of HMAC is considered.The mineral composition of the RAP is first analyzed,then the TLA modified asphalt with different levels of RAP content is used to assess the effect of RAP on the performance of the mixture.Finally,the high-temperature rheological properties of extracted bitumen and the adhesion characteristic between mineral and bitumen are analyzed.The results show that after RAP combustion,the yellowish and greyish minerals display different alkalinity values,while the greyish mineral exhibits an improved ability to combine with bitumen.Thus,RAP can significantly enhance the high-temperature rutting resistance of TLA modified asphalt mixtures.The aged bitumen in RAP makes the mixed binder harder and improves its rheological properties at high temperatures.展开更多
The study of the performances of the Archean of Man gneiss aggregates with the addition of filler to replace the basalt of Kasila group in the asphalt and concrete mix design of southern Sierra Leone is presented in t...The study of the performances of the Archean of Man gneiss aggregates with the addition of filler to replace the basalt of Kasila group in the asphalt and concrete mix design of southern Sierra Leone is presented in this document. The goal is to compare the results of the asphalt and concrete mix design with gneiss and basalt aggregate. The applied methods and design used are 1) Volumetric design and Marshall method for the asphalt, 2) French Dreux-Gorisse Method for the concrete. We added 2% of gneissic filler and 2% portland cement type 42.5 R to the asphalt hot mix with the gneiss aggregates to follow the criteria variation. The Marshall, the diametric compression and the Duriez tests require us to perform four different types of mix design. The four mix designs meet the requirements but F2 and F4 give the best mechanical properties. F2 (gneiss + 2% filler) and F4 (basalt) have many similarities from which we can conclude their interchangeability. F2 gives 5255 of optimal bitumen content. In regards to hydraulic concrete, the results of the compressive strength test (cement content 350 kg CMI 42.5 R/m3) with the gneiss and basalt aggregates are respectively 40 MPa and 45 MPa at 28 days curing: these values are greater than 35 MPa required by the technical specifications. The use of the Super Fluid ® Thermoplast 120 admixture, to increase the concrete compressive strength, is justified by the requirement of a minimum of 80% Rc28 at 24 hours. For both types of concrete, we have at 24 hours, 34 and 35 MPa which are higher than the minimum of 32 MPa (in 24 h). These results meet the requirements of the technical specifications.展开更多
Waste rubber-modified asphalt has good anti-aging properties and can significantly improve the service life of asphalt pavements. For domestic and foreign scholars of rubber modified asphalt thermal oxygen aging, phot...Waste rubber-modified asphalt has good anti-aging properties and can significantly improve the service life of asphalt pavements. For domestic and foreign scholars of rubber modified asphalt thermal oxygen aging, photo-oxidative aging and water aging some behavioural research, and rubber asphalt aging after the characteristics of the research progress are reviewed. Especially rubber-modified asphalt after light, water and other multi-factor agingsituations, the aging situation is more serious, for rubber-modified asphalt mixture aging, rubber asphalt anti-aging process research and analysis means are still very few, the future research must have more thinking.展开更多
Dynamic thermal mechanical analysis was used to evaluate the viscoelasticity of asphalt.The parameters included the energy storage modulus(E),the loss modulus(E'),and the loss tangent(tanδ).The impact of three ki...Dynamic thermal mechanical analysis was used to evaluate the viscoelasticity of asphalt.The parameters included the energy storage modulus(E),the loss modulus(E'),and the loss tangent(tanδ).The impact of three kinds of particles containing CaCO_(3)with different size and structure on the mechanical properties was also measured.The addition of limestone increases the glass transition temperature,while nanoCaCO_(3)@SiO_(2)decreases the glass transition temperature.Nano-CaCO_(3)has a negligible effect on the glass transition temperature.The particle size of the limestone is 0.075 mm,which is a material at the micrometer level.During the heating process,it hinders the molecular movement and makes the material harder.Thus the glass transition temperature is relatively high.展开更多
To explore the best preparation process for terminal blend(TB)composite-modified asphalt and to filter its formulation with excellent performance,this study evaluates the performance of TB composite modified asphalt b...To explore the best preparation process for terminal blend(TB)composite-modified asphalt and to filter its formulation with excellent performance,this study evaluates the performance of TB composite modified asphalt by physical property index,microscopic morphology,rheological testing,and infrared spectroscopy on multiple scales.The results show that the best preparation process for TB-modified asphalt is stirring at 260℃ for 4 h at 400 rpm,which significantly reduces the modification time of the asphalt.From a physical property viewpoint,the TB composite-modified asphalt sample with 5% styrene-butadiene-styrene(SBS)+1% aromatics+0.1% sulfur exhibits high-comprehensive,high-and low-temperature properties.More-over,its crosslinked mesh structure comprises black rubber particles uniformly interwoven in the middle,which further enhances the performance of the asphalt and results in an excellent performance formulation.In addition,the sample with 5%SBS content has a higher G*value and smaller δ value than that with 3%SBS content,indicating that its high-temperature resistance is improved.The effect of adding 3%SBS content on the viscoelastic ratio is,to some extent,less than that caused by 20% rubber powder.展开更多
To reduce the temperature diseases of asphalt pavement,improve the service quality of road and extend service life,the research of inorganic powders that reduce the temperature of asphalt pavements was systematically ...To reduce the temperature diseases of asphalt pavement,improve the service quality of road and extend service life,the research of inorganic powders that reduce the temperature of asphalt pavements was systematically sorted out.The common types,physicochemical properties and application methods of inorganic powders were defined.The road performances of modified asphalt and its mixture were evaluated.The modification mechanism of inorganic powders in asphalt was analyzed.On this basis,the cooling effect and cooling mechanism of inorganic powders was revealed.The results indicate that inorganic powders are classified into hollow,porous,and energy conversion types.The high-temperature performance of inorganic powders modified asphalt and its mixture is significantly improved,while there is no significant change in low-temperature performance and water stability.The average increase in rutting resistance factor(G*/sin(δ))and dynamic stability is 40%–72%and 30%–50%,respectively.The modification mechanism of inorganic powders in asphalt is physical blending.The thermal conductivity of hollow and porous inorganic powders modified asphalt mixture decreases by 30.05%and 43.14%,respectively.The temperature of hollow,porous and energy conversion inorganic powders modified asphalt mixture at 5 cm decreases by 2.3 ℃–3.5 ℃,0.8 ℃–3.7 ℃and 4.1 ℃–4.7℃,respectively.Hollow and porous inorganic powders block heat conduction,while energy conversion inorganic powders achieve cooling through their functional properties.展开更多
Determination of Shear Bond strength(SBS)at interlayer of double-layer asphalt concrete is crucial in flexible pavement structures.The study used three Machine Learning(ML)models,including K-Nearest Neighbors(KNN),Ext...Determination of Shear Bond strength(SBS)at interlayer of double-layer asphalt concrete is crucial in flexible pavement structures.The study used three Machine Learning(ML)models,including K-Nearest Neighbors(KNN),Extra Trees(ET),and Light Gradient Boosting Machine(LGBM),to predict SBS based on easily determinable input parameters.Also,the Grid Search technique was employed for hyper-parameter tuning of the ML models,and cross-validation and learning curve analysis were used for training the models.The models were built on a database of 240 experimental results and three input variables:temperature,normal pressure,and tack coat rate.Model validation was performed using three statistical criteria:the coefficient of determination(R2),the Root Mean Square Error(RMSE),and the mean absolute error(MAE).Additionally,SHAP analysis was also used to validate the importance of the input variables in the prediction of the SBS.Results show that these models accurately predict SBS,with LGBM providing outstanding performance.SHAP(Shapley Additive explanation)analysis for LGBM indicates that temperature is the most influential factor on SBS.Consequently,the proposed ML models can quickly and accurately predict SBS between two layers of asphalt concrete,serving practical applications in flexible pavement structure design.展开更多
This study investigates the mechanism of action of representative molecules of basalt fibers on the healing of water-soaked asphalt.Thermodynamic parameters,morphological characteristics,interfacial healing energy,and...This study investigates the mechanism of action of representative molecules of basalt fibers on the healing of water-soaked asphalt.Thermodynamic parameters,morphological characteristics,interfacial healing energy,and interfacial healing strength were analyzed using molecular dynamics and macroscopic tests under different time,temperature,and water conditions to evaluate the specific states and critical conditions involved in self-healing.The results indicate that basalt-fiber molecules can induce rearrangement and a combination of water-soaked asphalt at the healing interface.Hydroxyl groups with different bonding states increase the interfacial adsorption capacity of water-soaked asphalt.The interaction between basalt fiber molecules and water molecules leads to a"hoop"phenomenon,while aromatics-2 molecules exhibit a"ring band aggregation"phenomenon.The former reduces the miscibility of water and asphalt molecules,while the latter causes slow diffusion of the components.Furthermore,a micro-macro dual-scale comparison of interfacial healing strength was conducted at temperatures of 297.15 and 312.15 K to identify the strength transition point and critical temperature of 299.4 K during the self-healing process of basalt-fiber modified water-soaked asphalt.展开更多
Graphene oxide nanomaterials are increasingly used in various fields due to their superior properties.In order to study the influence of graphene oxide additives on the performance of modified asphalt,in this study,gr...Graphene oxide nanomaterials are increasingly used in various fields due to their superior properties.In order to study the influence of graphene oxide additives on the performance of modified asphalt,in this study,graphene oxide modified asphalt was prepared and characteristics was studied including the high deformation resistance performance and the self-healing property of modified asphalt.Functional groups and morphology of graphene oxide modified asphalt were described by Fourier transform infrared spectroscopy.The high deformation resistance performance and self-healing effect of asphalt samples were obtained through dynamic slear rheometer(DSR)test.Results shows that graphene oxide dispersions improve the performance of asphalt relatively well compared to graphene oxide powder.There is no chemical reaction between graphene oxide and asphalt,but physical connection.The addition of graphene oxide improved the high deformation resistance of modified asphalt and expedited the self-healing ability of asphalt under fatigue load.展开更多
Isocyanate and its products are playing an increasingly important role in the high-performance development of asphalt pavement,but researchers have always focused on polyurethane(PU),one of the isocyanate products,and...Isocyanate and its products are playing an increasingly important role in the high-performance development of asphalt pavement,but researchers have always focused on polyurethane(PU),one of the isocyanate products,and neglected the other roles of isocyanate-based materials in asphalt pavement.The application of isocyanate-based materials in asphalt pavement is still in the exploratory stage,and the research direction is not clear.It is necessary to summarize and propose research directions for the application of isocyanate-based materials in asphalt pavement.Therefore,this paper reviews the application of isocyanate-based materials in asphalt pavement,classifies the products synthesized from isocyanate for asphalt binder,introduces the application effects of different isocyanate-based materials in asphalt binder,and analyzes the limitations of each material.Meanwhile,the other roles of isocyanate-based materials in asphalt pavement,such as coating materials and adhesive materials,are summarized.Finally,the development direction of isocyanate-based materials in asphalt pavement is prospected.Isocyanate-based materials are expected to significantly increase the service life of asphalt pavement because of their excellent properties.With the advancement of technology,the application of isocyanate-based materials will become more and more common,promoting the sustainable development of road construction.This paper can provide a reference for the development and application of isocyanate-based materials in asphalt pavement.展开更多
Warm mix asphalt(WMA)has gained significant attention in the asphalt industry,tradi-tionally dominated by Hot mix asphalt(HMA),due to its advantages in reducing energy consumption and lowering carbon emissions.This st...Warm mix asphalt(WMA)has gained significant attention in the asphalt industry,tradi-tionally dominated by Hot mix asphalt(HMA),due to its advantages in reducing energy consumption and lowering carbon emissions.This study introduces an innovative warm mix technology,soft-hard compound warm mix asphalt(SHC-WMA),which combines the low softening point of soft asphalt for effective coating of aggregate particles at reduced temperatures,with the high viscosity and aging resistance of rock asphalt to enhance the mixture’s overall performance.Unlike conventional WMA technologies,SHC-WMA was specifically developed with an optimized mixing temperature as a critical design parame-ter.Through extensive laboratory and field testing,this paper evaluates and compares the road performance,compaction efficiency,emissions reduction,energy savings,and cost-effectiveness of SHC-WMA against Sasobit Warm mix asphalt(SA-WMA)and HMA.The results highlight the superior performance of SHC-WMA,particularly in high-temperature stability and fatigue resistance.SHC-WMA demonstrates a 25%improvement in rutting resistance over HMA and a 15%increase in fatigue life compared to SA-WMA,making it highly suitable for long-term road applications.Furthermore,SHC-WMA signif-icantly outperforms both HMA and SA-WMA in terms of environmental impact,achieving reductions in CO_(2) emissions by 27.0%,particulate matter by 35.0%,and benzo[a]pyrene emissions by 55.3%compared to HMA.In terms of energy efficiency,SHC-WMA reduces diesel consumption for asphalt heating by 83.2%and heavy oil consumption for aggregate heating by 28.3%when compared to HMA.The cost of SHC-WMA is 7.7%higher than HMA,and represents 99.2%of the cost of SA-WMA.Additionally,SHC-WMA exhibits the lowest rut depth after eight years of service,indicating its superior long-term performance.展开更多
The use of epoxy resin(EP)to prepare epoxy recycled asphalt mixture can achieve the reuse of 100%reclaimed asphalt pavement(RAP).However,the high stiffness and brittleness of epoxy resin result in insufficient crack r...The use of epoxy resin(EP)to prepare epoxy recycled asphalt mixture can achieve the reuse of 100%reclaimed asphalt pavement(RAP).However,the high stiffness and brittleness of epoxy resin result in insufficient crack resistance of mixture.To address the issue,dry-method styrene-butadiene-styrene(DSBS)and epoxy resin were mixed with aged asphalt to prepare SBS-modified epoxy reclaimed asphalt(SERA).The micro fusion characteristics and mechanical properties of SERA were evaluated,and the optimal DSBS dosage was determined based on various tests.The results show that adding DSBS can enable the tensile toughness and low-temperature performance of SERA with less EP content to reach or exceed the performance level of epoxy reclaimed asphalt(ERA)with higher EP content.At 30%EP content,the recommended dry-method SBS content is 9%;At 40%EP content,the recommended dry-method SBS content is 5%;When the EP content is 50%,the recommended dry-method SBS content is 7%.展开更多
Aluminum industrial solid waste represents a highly abundant yet underutilized resource.Its incorporation into asphalt pavement applications can effectively reduce the exploitation of natural resources and mitigate en...Aluminum industrial solid waste represents a highly abundant yet underutilized resource.Its incorporation into asphalt pavement applications can effectively reduce the exploitation of natural resources and mitigate environmental issues caused by waste accumulation.This paper focuses on typical solid waste resources generated by the aluminum industry,summarizing the latest research progress in their application within the asphalt pavement industry and proposing key directions for future attention.The physicochemical properties of red mud(RM),spent aluminum electrolytic cathode materials,and secondary aluminum dross(SAD)are reviewed.The effects and mechanisms of RM,spent aluminum electrolytic cathode materials,and SAD on the performance of asphalt and its mixtures are elaborated.RM significantly enhances the aging resistance of asphalt,the hightemperature rheological properties of asphalt mastic,and the rutting resistance of asphalt mixtures.Spent aluminum electrolytic cathode materials require the removal of fluorides and cyanides before further application in asphalt pavement.SAD effectively improves the dynamic stability of asphalt mixtures.This review presents the first systematic summary of key scientific challenges and technical bottlenecks in the application of aluminum industrial solid waste in asphalt pavements.It clarifies that future research should prioritize waste pretreatment technologies,performance regulation mechanisms,and life cycle environmental impact assessments.These contributions provide essential theoretical foundations and technical guidance for advancing the resource utilization of aluminum industrial solid waste,holding substantial significance for promoting the development of green transportation infrastructure.展开更多
基金The National Natural Science Foundation of China(No.50778057)
文摘A kind of neat asphalt and three kinds of diatomite asphalt are tested using differential scanning calorimetry（DSC）. The anti-cracking mechanism of diatomite asphalt is analyzed by DSC and the thermal stress restrained specimen test（TSRST） of the asphalt mixtures. The results show that the low temperature performance of diatomite asphalt is better than that of neat asphalt. The glass transition temperature can reflect the low temperature performance of the diatomite asphalt better and has a good relationship with breaking temperatures. Besides, the TSRST, the bending test, the compressing test and the contraction coefficient test are used to study the low temperature performance of the diatomite asphalt mixture. The results prove that the low temperature performance of the diatomite asphalt mixture is better than that of the neat asphalt mixture. The critical bending strain energy density and the compressing strain energy density of the diatomite asphalt mixture are greater than those of the neat asphalt mixture. After adding diatomite to the asphalt mixture, the contraction coefficient is reduced. Based on the above results, the anti-cracking mechanism of the diatomite asphalt mixture is analyzed from the angle of contraction performance and breaking energy.
基金National Basic Research Program of China (2004CB217808)National Natural Science Foundation of China (20471041, 90306014)+1 种基金Natural Science Foundation of Shanxi Province (20051018)Shanxi Research Fund for Returned Scholars (200428)
文摘The deoiled asphalt as the carbon source and the ferrocene as the metal source and the catalyst precursor were chosen to synthesize iron-containing carbon microparticles through co-carbonization at the temperature of about 450℃ for 3 h. The resulting products were treated at 2 000 ℃ for 2 h. All samples were examined by high resolution transmission electron microscopy （HRTEM） and X-ray diffraction （XRD）. The results show that the iron particles in the heat-treated material are completely coated by carbon. In addition to the fully filled carbon microparticles as well as hollow carbon ones, also form carbon fibers with hollow centers. The formation mechanism of the as-prepared products was discussed briefly.
基金Funded by Jiangsu Transportation Research Program(No. 05Y07)
文摘Through scanning electron microscope （SEM）, spectral analysis, and component analysis tests, the interaction theory between asphalt and rubber was discussed. It is concluded that rubber powder become soft and bond together with each other after being mixed with asphalt. The asphalt changes from a smooth homogeneous matter to a continuous mixing system which is composed of rubber powder and asphalt. The interaction is mainly physical diffusion, but there are some chemical reactions in the process, especially at long reaction time.
基金the National Natural Science Foundation of China(Nos.51108138,51008099)the Program for New Century Excellent Talents in University by Ministry of Education(No.NCET-06–0340)
文摘In order to find a parameter as the evaluation index that can capture the effect of the interaction between asphalt and aggregate, the rheological properties of asphalt mastics using two kinds of asphalts and four kinds of aggregates under different filler-asphalt ratios were measured by a dynamic shear rheometer （DSR）. Moreover, four rheological parameters of K.Ziegel-B, Luis Ibrarra-A, complex shear modulus ΔG＊and complex viscosity Δη＊ for evaluating the interaction ability were studied. Results indicate that all the four parameters can characterize the interaction ability of asphalt and aggregate correctly and feasibly. Through the comparison of sensitivities and physical meanings of the four parameters, K.Ziegel-B with high sensitivity and exact physical meaning is finally selected as the evaluation index for interaction ability of asphalt and aggregate.
基金supported by Innovation Capability Support Program of Shaanxi(2022TD-07).
文摘With the rapid development of asphalt pavement technology,it has attracted considerable attention to improving the durability of asphalt pavement.An effective action is to use modified asphalt with high performance and durability.Polyurethane(PU)has been used in asphalt pavement engineering to enhance the durability and service life of asphalt pavement because of its excellent high-temperature performance,toughness,wear resistance,aging resistance and oil resistance.However,PU modified asphalt technology is still in the exploratory stage.The preparation,modification mechanism and working performances of PU modified asphalt need to be further clarified.Therefore,this paper summarized the research progress of PU modified asphalt and its mixture.The composition of PU modified asphalt was introduced.The addition methods of PU materials and preparation process parameters of the PU modified asphalt were determined.The modification mechanism of PU on asphalt was discussed.The effects of polyurethane on asphalt were analyzed and the road performances of its mixture were evaluated.Finally,the development tendency towards PU modified asphalt and its mixture were forecasted.
基金supported by Natural Science Foundation of Guangxi Province under Grant No.2020GXNSFGA297001the National Natural Science Foundation of China(51768007).
文摘Asphalt mixtures and cement concrete are an important material in the construction of roads,highways and buildings,and there has been a lot of research about the improvement of their performance.Among them,fibers are commonly used in the construction industry because of their superior properties as reinforcing materials that can provide a proper interfacial action between the fibers and the substrate.This review classifies fibers into natural fibers,inorganic fibers and polymer fibers according to their sources and properties.It summarizes and compares the characteristics,modification methods,usage requirements and research status of each type of fiber in asphalt and cement construction materials,and analyzes the problems and challenges faced by fibers in their applications.The evaluation results show that various types of fibers can enhance the fracture resistance,tensile strength and rutting resistance of asphalt to a certain extent,improve the high temperature performance and viscoelasticity of asphalt,and have a certain effect on the fatigue resistance and road water resistance of asphalt mixes.The fibers also provide better tensile,compressive and abrasion resistance to cement concrete and improve the brittleness and crack resistance of ordinary cement.Besides,for some defects of various types of fibers in construction materials,such as biodegradability,dispersibility and surface inertness of fibers,the targeted modification of fibers is introduced based on physical and chemical modification methods to improve the performance impact of modified fibers in various conditions of application.
文摘Within the past two decades or so, the asphalt paving industry has responded positively to increasing global concerns over shrinking natural resource reserves and worsening environmental conditions through the development and deployment of warm-mix asphalt technologies. Such technologies make it possible to produce and place asphalt concrete at reduced temperatures compared to conventional hot-mix methods. Several studies have reported on the potential of warm-mix asphalt with regard to improved pavement performance, efficiency and environmental stewardship. This paper reviews several of those studies in the context of pavement sustainability. Overall, warm-mix asphalt provides substantial sustainability benefits similar to or, in some cases, better than conventional hot-mix asphalt. Sustainability benefits include lower energy use, reduced emissions, and potential for increased reclaimed asphalt pavement usage. Growth in utilization of warm-mix asphalt worldwide may, in the not-too-distant future, make the material the standard for asphalt paving. Regardless, there are concerns over some aspects of warm-mix asphalt such as lower resistance to fatigue cracking, rutting and potential water-susceptibility problems, particularly with mixes prepared with water-based technologies, which require further research to address.
基金This work was funded by the Self-Financing Technology Plan Project of Foshan(2020001005386)Open Fund of Key Laboratory of Geological Survey and Evaluation of Ministry of Education(No.GLAB2019ZR01).
文摘Rutting of asphalt pavement occurs earlier and is more serious under the increasingly heavy traffic load conditions that can be found in subtropical monsoon climate regions.High modulus asphalt concrete(HMAC)with excellent anti-rutting and anti-fatigue properties is generally used to mitigate this issue.Given the relatively high cost of the additives used in this type of asphalt,in this study the feasibility of using recycled asphalt mixture(RAP)and Trinidad lake asphalt(TLA)for the preparation of HMAC is considered.The mineral composition of the RAP is first analyzed,then the TLA modified asphalt with different levels of RAP content is used to assess the effect of RAP on the performance of the mixture.Finally,the high-temperature rheological properties of extracted bitumen and the adhesion characteristic between mineral and bitumen are analyzed.The results show that after RAP combustion,the yellowish and greyish minerals display different alkalinity values,while the greyish mineral exhibits an improved ability to combine with bitumen.Thus,RAP can significantly enhance the high-temperature rutting resistance of TLA modified asphalt mixtures.The aged bitumen in RAP makes the mixed binder harder and improves its rheological properties at high temperatures.
文摘The study of the performances of the Archean of Man gneiss aggregates with the addition of filler to replace the basalt of Kasila group in the asphalt and concrete mix design of southern Sierra Leone is presented in this document. The goal is to compare the results of the asphalt and concrete mix design with gneiss and basalt aggregate. The applied methods and design used are 1) Volumetric design and Marshall method for the asphalt, 2) French Dreux-Gorisse Method for the concrete. We added 2% of gneissic filler and 2% portland cement type 42.5 R to the asphalt hot mix with the gneiss aggregates to follow the criteria variation. The Marshall, the diametric compression and the Duriez tests require us to perform four different types of mix design. The four mix designs meet the requirements but F2 and F4 give the best mechanical properties. F2 (gneiss + 2% filler) and F4 (basalt) have many similarities from which we can conclude their interchangeability. F2 gives 5255 of optimal bitumen content. In regards to hydraulic concrete, the results of the compressive strength test (cement content 350 kg CMI 42.5 R/m3) with the gneiss and basalt aggregates are respectively 40 MPa and 45 MPa at 28 days curing: these values are greater than 35 MPa required by the technical specifications. The use of the Super Fluid ® Thermoplast 120 admixture, to increase the concrete compressive strength, is justified by the requirement of a minimum of 80% Rc28 at 24 hours. For both types of concrete, we have at 24 hours, 34 and 35 MPa which are higher than the minimum of 32 MPa (in 24 h). These results meet the requirements of the technical specifications.
文摘Waste rubber-modified asphalt has good anti-aging properties and can significantly improve the service life of asphalt pavements. For domestic and foreign scholars of rubber modified asphalt thermal oxygen aging, photo-oxidative aging and water aging some behavioural research, and rubber asphalt aging after the characteristics of the research progress are reviewed. Especially rubber-modified asphalt after light, water and other multi-factor agingsituations, the aging situation is more serious, for rubber-modified asphalt mixture aging, rubber asphalt anti-aging process research and analysis means are still very few, the future research must have more thinking.
基金Funded by National Natural Science Foundation of China(No.52472033)。
文摘Dynamic thermal mechanical analysis was used to evaluate the viscoelasticity of asphalt.The parameters included the energy storage modulus(E),the loss modulus(E'),and the loss tangent(tanδ).The impact of three kinds of particles containing CaCO_(3)with different size and structure on the mechanical properties was also measured.The addition of limestone increases the glass transition temperature,while nanoCaCO_(3)@SiO_(2)decreases the glass transition temperature.Nano-CaCO_(3)has a negligible effect on the glass transition temperature.The particle size of the limestone is 0.075 mm,which is a material at the micrometer level.During the heating process,it hinders the molecular movement and makes the material harder.Thus the glass transition temperature is relatively high.
基金Funded by the National Natural Science Foundation of China(No.52278446)。
文摘To explore the best preparation process for terminal blend(TB)composite-modified asphalt and to filter its formulation with excellent performance,this study evaluates the performance of TB composite modified asphalt by physical property index,microscopic morphology,rheological testing,and infrared spectroscopy on multiple scales.The results show that the best preparation process for TB-modified asphalt is stirring at 260℃ for 4 h at 400 rpm,which significantly reduces the modification time of the asphalt.From a physical property viewpoint,the TB composite-modified asphalt sample with 5% styrene-butadiene-styrene(SBS)+1% aromatics+0.1% sulfur exhibits high-comprehensive,high-and low-temperature properties.More-over,its crosslinked mesh structure comprises black rubber particles uniformly interwoven in the middle,which further enhances the performance of the asphalt and results in an excellent performance formulation.In addition,the sample with 5%SBS content has a higher G*value and smaller δ value than that with 3%SBS content,indicating that its high-temperature resistance is improved.The effect of adding 3%SBS content on the viscoelastic ratio is,to some extent,less than that caused by 20% rubber powder.
基金supported by Fundamental Research Funds for the Central Universities(300102214908)Innovation Capability Support Program of Shaanxi(2022TD-07).
文摘To reduce the temperature diseases of asphalt pavement,improve the service quality of road and extend service life,the research of inorganic powders that reduce the temperature of asphalt pavements was systematically sorted out.The common types,physicochemical properties and application methods of inorganic powders were defined.The road performances of modified asphalt and its mixture were evaluated.The modification mechanism of inorganic powders in asphalt was analyzed.On this basis,the cooling effect and cooling mechanism of inorganic powders was revealed.The results indicate that inorganic powders are classified into hollow,porous,and energy conversion types.The high-temperature performance of inorganic powders modified asphalt and its mixture is significantly improved,while there is no significant change in low-temperature performance and water stability.The average increase in rutting resistance factor(G*/sin(δ))and dynamic stability is 40%–72%and 30%–50%,respectively.The modification mechanism of inorganic powders in asphalt is physical blending.The thermal conductivity of hollow and porous inorganic powders modified asphalt mixture decreases by 30.05%and 43.14%,respectively.The temperature of hollow,porous and energy conversion inorganic powders modified asphalt mixture at 5 cm decreases by 2.3 ℃–3.5 ℃,0.8 ℃–3.7 ℃and 4.1 ℃–4.7℃,respectively.Hollow and porous inorganic powders block heat conduction,while energy conversion inorganic powders achieve cooling through their functional properties.
基金the University of Transport Technology under grant number DTTD2022-12.
文摘Determination of Shear Bond strength(SBS)at interlayer of double-layer asphalt concrete is crucial in flexible pavement structures.The study used three Machine Learning(ML)models,including K-Nearest Neighbors(KNN),Extra Trees(ET),and Light Gradient Boosting Machine(LGBM),to predict SBS based on easily determinable input parameters.Also,the Grid Search technique was employed for hyper-parameter tuning of the ML models,and cross-validation and learning curve analysis were used for training the models.The models were built on a database of 240 experimental results and three input variables:temperature,normal pressure,and tack coat rate.Model validation was performed using three statistical criteria:the coefficient of determination(R2),the Root Mean Square Error(RMSE),and the mean absolute error(MAE).Additionally,SHAP analysis was also used to validate the importance of the input variables in the prediction of the SBS.Results show that these models accurately predict SBS,with LGBM providing outstanding performance.SHAP(Shapley Additive explanation)analysis for LGBM indicates that temperature is the most influential factor on SBS.Consequently,the proposed ML models can quickly and accurately predict SBS between two layers of asphalt concrete,serving practical applications in flexible pavement structure design.
文摘This study investigates the mechanism of action of representative molecules of basalt fibers on the healing of water-soaked asphalt.Thermodynamic parameters,morphological characteristics,interfacial healing energy,and interfacial healing strength were analyzed using molecular dynamics and macroscopic tests under different time,temperature,and water conditions to evaluate the specific states and critical conditions involved in self-healing.The results indicate that basalt-fiber molecules can induce rearrangement and a combination of water-soaked asphalt at the healing interface.Hydroxyl groups with different bonding states increase the interfacial adsorption capacity of water-soaked asphalt.The interaction between basalt fiber molecules and water molecules leads to a"hoop"phenomenon,while aromatics-2 molecules exhibit a"ring band aggregation"phenomenon.The former reduces the miscibility of water and asphalt molecules,while the latter causes slow diffusion of the components.Furthermore,a micro-macro dual-scale comparison of interfacial healing strength was conducted at temperatures of 297.15 and 312.15 K to identify the strength transition point and critical temperature of 299.4 K during the self-healing process of basalt-fiber modified water-soaked asphalt.
基金supported by Gansu Provincial Science and Technology Plan(23CXGA0195)Longnan Science and Technology Plan(2024CX03)。
文摘Graphene oxide nanomaterials are increasingly used in various fields due to their superior properties.In order to study the influence of graphene oxide additives on the performance of modified asphalt,in this study,graphene oxide modified asphalt was prepared and characteristics was studied including the high deformation resistance performance and the self-healing property of modified asphalt.Functional groups and morphology of graphene oxide modified asphalt were described by Fourier transform infrared spectroscopy.The high deformation resistance performance and self-healing effect of asphalt samples were obtained through dynamic slear rheometer(DSR)test.Results shows that graphene oxide dispersions improve the performance of asphalt relatively well compared to graphene oxide powder.There is no chemical reaction between graphene oxide and asphalt,but physical connection.The addition of graphene oxide improved the high deformation resistance of modified asphalt and expedited the self-healing ability of asphalt under fatigue load.
基金The authors are appreciative of the financial assistance granted by the National Natural Science Foundation of China(No.52378462)Guangdong Basic and Applied Basic Research Foundation(No.2023A1515011448).
文摘Isocyanate and its products are playing an increasingly important role in the high-performance development of asphalt pavement,but researchers have always focused on polyurethane(PU),one of the isocyanate products,and neglected the other roles of isocyanate-based materials in asphalt pavement.The application of isocyanate-based materials in asphalt pavement is still in the exploratory stage,and the research direction is not clear.It is necessary to summarize and propose research directions for the application of isocyanate-based materials in asphalt pavement.Therefore,this paper reviews the application of isocyanate-based materials in asphalt pavement,classifies the products synthesized from isocyanate for asphalt binder,introduces the application effects of different isocyanate-based materials in asphalt binder,and analyzes the limitations of each material.Meanwhile,the other roles of isocyanate-based materials in asphalt pavement,such as coating materials and adhesive materials,are summarized.Finally,the development direction of isocyanate-based materials in asphalt pavement is prospected.Isocyanate-based materials are expected to significantly increase the service life of asphalt pavement because of their excellent properties.With the advancement of technology,the application of isocyanate-based materials will become more and more common,promoting the sustainable development of road construction.This paper can provide a reference for the development and application of isocyanate-based materials in asphalt pavement.
基金supported by the National Natural Science Foundation of China(No.52278455)the highway administration bureau of Hangzhou.
文摘Warm mix asphalt(WMA)has gained significant attention in the asphalt industry,tradi-tionally dominated by Hot mix asphalt(HMA),due to its advantages in reducing energy consumption and lowering carbon emissions.This study introduces an innovative warm mix technology,soft-hard compound warm mix asphalt(SHC-WMA),which combines the low softening point of soft asphalt for effective coating of aggregate particles at reduced temperatures,with the high viscosity and aging resistance of rock asphalt to enhance the mixture’s overall performance.Unlike conventional WMA technologies,SHC-WMA was specifically developed with an optimized mixing temperature as a critical design parame-ter.Through extensive laboratory and field testing,this paper evaluates and compares the road performance,compaction efficiency,emissions reduction,energy savings,and cost-effectiveness of SHC-WMA against Sasobit Warm mix asphalt(SA-WMA)and HMA.The results highlight the superior performance of SHC-WMA,particularly in high-temperature stability and fatigue resistance.SHC-WMA demonstrates a 25%improvement in rutting resistance over HMA and a 15%increase in fatigue life compared to SA-WMA,making it highly suitable for long-term road applications.Furthermore,SHC-WMA signif-icantly outperforms both HMA and SA-WMA in terms of environmental impact,achieving reductions in CO_(2) emissions by 27.0%,particulate matter by 35.0%,and benzo[a]pyrene emissions by 55.3%compared to HMA.In terms of energy efficiency,SHC-WMA reduces diesel consumption for asphalt heating by 83.2%and heavy oil consumption for aggregate heating by 28.3%when compared to HMA.The cost of SHC-WMA is 7.7%higher than HMA,and represents 99.2%of the cost of SA-WMA.Additionally,SHC-WMA exhibits the lowest rut depth after eight years of service,indicating its superior long-term performance.
基金Funded by the National Natural Science Foundation of China(Nos.52378444,52078130)the Natural Science Foundation of Shandong Province(No.ZR2021QE250)。
文摘The use of epoxy resin(EP)to prepare epoxy recycled asphalt mixture can achieve the reuse of 100%reclaimed asphalt pavement(RAP).However,the high stiffness and brittleness of epoxy resin result in insufficient crack resistance of mixture.To address the issue,dry-method styrene-butadiene-styrene(DSBS)and epoxy resin were mixed with aged asphalt to prepare SBS-modified epoxy reclaimed asphalt(SERA).The micro fusion characteristics and mechanical properties of SERA were evaluated,and the optimal DSBS dosage was determined based on various tests.The results show that adding DSBS can enable the tensile toughness and low-temperature performance of SERA with less EP content to reach or exceed the performance level of epoxy reclaimed asphalt(ERA)with higher EP content.At 30%EP content,the recommended dry-method SBS content is 9%;At 40%EP content,the recommended dry-method SBS content is 5%;When the EP content is 50%,the recommended dry-method SBS content is 7%.
基金supported by the National Natural Science Foundation of China(No.52368058)Guangxi Science and Technology Program(Gui Ke AB23026067).
文摘Aluminum industrial solid waste represents a highly abundant yet underutilized resource.Its incorporation into asphalt pavement applications can effectively reduce the exploitation of natural resources and mitigate environmental issues caused by waste accumulation.This paper focuses on typical solid waste resources generated by the aluminum industry,summarizing the latest research progress in their application within the asphalt pavement industry and proposing key directions for future attention.The physicochemical properties of red mud(RM),spent aluminum electrolytic cathode materials,and secondary aluminum dross(SAD)are reviewed.The effects and mechanisms of RM,spent aluminum electrolytic cathode materials,and SAD on the performance of asphalt and its mixtures are elaborated.RM significantly enhances the aging resistance of asphalt,the hightemperature rheological properties of asphalt mastic,and the rutting resistance of asphalt mixtures.Spent aluminum electrolytic cathode materials require the removal of fluorides and cyanides before further application in asphalt pavement.SAD effectively improves the dynamic stability of asphalt mixtures.This review presents the first systematic summary of key scientific challenges and technical bottlenecks in the application of aluminum industrial solid waste in asphalt pavements.It clarifies that future research should prioritize waste pretreatment technologies,performance regulation mechanisms,and life cycle environmental impact assessments.These contributions provide essential theoretical foundations and technical guidance for advancing the resource utilization of aluminum industrial solid waste,holding substantial significance for promoting the development of green transportation infrastructure.
