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• Thermal resistance aggregates wrapped with organosilicon resin are prepared. • The surface wrapping effect of different thermal resistance aggregates are evaluated. • The indoor sunlight simulation device is designed to test the heat resistance performance. To improve the road performance and heat resistance of thermal resistance aggregates, thermal resistance aggregates wrapped with organosilicon resin were prepared. The optimal surface treatment process of different thermal resistance aggregates was determined. The surface wrapping effect of different thermal resistance aggregates were evaluated based on the macropore structure and microsurface morphology. In addition, the road performance of different thermal resistance aggregates before and after surface treatment were compared and analyzed. The heat resistance performance of different thermal resistance asphalt mixtures was tested by an indoor sunlight simulation test. Furthermore, the effect of surface treatment on road performance and heat resistance of a thermal resistance asphalt mixture was evaluated. The results showed that the surface treatment of shale ceramsite with organosilicon resin achieved the best result. The 24 h oil absorption decreased to 2.05%. The surface pore sealing rate was as high as 78.3%, and the opening pores could hardly be seen in the SEM images. After being surface treated with organosilicon resin, the water absorption, crushing value and abrasion value of three kinds of thermal resistance aggregates decreased by 82.87%–94.50%, 6.8%–22.07% and 10.87%–28.56%, respectively, and their adhesion increased to grade 5. The surface treatment of thermal resistance aggregates could significantly improve the high temperature performance and water stability of thermal resistance asphalt mixtures. There was little effect on the low temperature performance, while the heat resistance performance of the thermal resistance asphalt mixture was improved to varying degrees. [ABSTRACT FROM AUTHOR]

Highlights • The performance of steel sleepers reinforced by rubber layers and web steel stiffeners are evaluated. • Lateral resistance of steel sleepers is investigated by the single tie push test. • The contribution of ballast components to the lateral resistance are obtained. Abstract In this study, the lateral resistance of different types of steel sleepers, placed on the ballast layer with a variety of shoulder height and shoulder width, has been investigated. A number of single tie push tests were conducted to examine the effect of bumped-rubber layers and web steel stiffeners on the ballast/sleeper interaction. In the next step, DEM simulations of STPTs were developed by PFC3D to estimate the contribution of shoulder ballast height to the lateral resistance of steel sleepers. According to the laboratory results, the use of 3 web steel stiffeners caused about 70% increase in the lateral resistance in comparison with the conventional steel sleeper. On the other hand, DEM simulation results indicate that ballast bed had a higher proportion to the lateral resistance of steel sleepers than that of all the other ballast components and using web steel stiffeners could increase by 9% the contribution of the bottom surface of steel sleepers to ballast/sleeper interaction. [ABSTRACT FROM AUTHOR]

• The pavement conductive interlayer bonding materials were prepared. • The temperature rise effect of the conductive bonding layer in pavement structure was evaluated. • The feasibility of using conductive bonding layer to realize the pavement deicing and snow melting was verified. The purpose is to realize the environmental friendliness and sustainability of pavement active deicing and snow melting. Different types of SBS modified asphalt conductive bonding materials for pavement interlayer bonding and melting ice and snow were prepared. The effects of conductive phase materials, electrodes and spacing on the conductivity and heat generation of conductive bonding layer were studied. The heating effect of SBS modified asphalt conductive bonding layer in pavement structure was analyzed. The feasibility of converting electric energy into heat energy by conductive bonding layer to realize melting ice and snow on pavement was verified. It provides a new direction for the research and application of green active deicing and snow melting. The results show that the carbon fiber conductive bonding layer had the best conductivity. At the constant temperature of −5 °C, the surface temperature of the pavement structure could reach above 0 °C after the conductive bonding layer was electrified for 100 min under 36 V voltage, which can realize the deicing and snow melting of the pavement. The distribution of carbon fiber has a certain adverse effect on the bonding performance of conductive bonding layers, but it still shows good bonding performance, water resistance and temperature change resistance. [ABSTRACT FROM AUTHOR]

• Innovated sleeper shape with texture attached at sleeper bottom. • Comparison of different friction sleeper design. • Discrete element modelling of sleeper-ballast interaction. • A rapid method for discrete element method model construction. The lateral stability of ballasted track becomes more important because of the safety requirement under the demand of higher train speed and heavier axle load. To increase the lateral resistance of ballast bed, this paper proposes three types of new sleepers, frictional sleepers. The frictional sleepers are sleepers with different shapes of textures attached at the sleeper bottom. To study the application feasibility of the frictional sleepers, experimental tests (single sleeper pull-out test) and numerical simulation (discrete element modelling) are performed. The lateral resistances of the three types of frictional sleepers are compared with the traditional sleeper based on the experimental test, and the mechanism of the lateral resistance increase is revealed according to the numerical simulation. The results indicate that the frictional sleepers can increase the lateral resistance by 32% (maximum), due to the enhanced interaction between sleeper and ballast particles. More importantly, different types of frictional sleepers have different performances, and the optimal friction sleeper is confirmed. This study is helpful for the further research on sleeper design. [ABSTRACT FROM AUTHOR]

This study investigates the mechanical and microstructural responses of Ultra-High Performance Concrete (UHPC) subjected to a substantial number of thermal cycles upto 300 times from ambient temperature to 60°C. The experimental findings reveal a distinctive pattern of behavior in the static compressive strength, characterized by an initial increase, followed by a subsequent decline, and a subsequent modest resurgence as the thermal cycling progressed. Notably, the peak compressive and flexural strengths were attained after 120 thermal cycles, whereas the maximum dynamic compressive strength was observed after 60 thermal cycles. It is worth highlighting that the dynamic increase factor (DIF) exhibited an inverse trajectory in comparison to the static compressive strength. After 120 thermal cycles, the stress-strain curves under impact loads exhibited pronounced strain softening characteristics, with an oscillation state duration of 250μs, which surpassed that of the ascending and descending phases. The observed variances in macroscopic mechanical properties can be attributed to several pivotal factors, including the quantity of hydration product, the mean chain length (MCL) of the calcium-silicate-hydrate (C-S-H) gel, the distribution of pore volume, and the presence of micro-cracks. This comprehensive examination serves as a valuable theoretical and empirical foundation for advancing the utilization of UHPC in applications subjected to prolonged and intricate thermal conditions. • The effect of 60℃ thermal cycling on UHPC was studied. • The peak compressive and flexural strengths were attained after 120 thermal cycles. • The maximum dynamic compressive strength was observed after 60 thermal cycles. • The stress-strain curves under impact loads exhibited pronounced strain softening characteristics. [ABSTRACT FROM AUTHOR]

Highlights • Lateral resistance of ladder sleepers is investigated by the lateral track panel test. • The contribution of ballast components to the lateral resistance is obtained. • The DEM simulation of a ladder sleeper on the ballast layer was performed. Abstract The sleeper-ballast interface of railway tracks directly is associated with lateral resistance which plays an important role in the mechanical behavior of ballasted tracks. In a real-case implementation of ballasted track for speeds as high as 400 km/h, sufficient lateral resistance is vital to prevent the lateral movement of the track. In view of the future development, a series of full-scale lateral track panel tests (LTPT) were conducted to evaluate the lateral resistance of ladder sleepers as a substitution of monoblock sleepers. The experimental results revealed that the application of the ladder sleepers caused an increase in lateral resistance of the ballasted track as well as a reduction in the use of ballast aggregates. In addition, the contribution of the ladder sleeper facets to the lateral resistance was investigated by the discrete element method (DEM). In conclusion, crib ballast has the main role in the lateral resistance of ladder sleeper tracks. [ABSTRACT FROM AUTHOR]

Highlights • The cooling effects of different new road cooling coatings. • Durability evaluation indexes under different composite operating conditions. • Multi-objective grey target decision-making method. Abstract A comprehensive durability evaluation system for road cooling coating had not yet been constructed. Aimed at this objective, different new road cooling coatings were prepared based on a variety of selected raw materials, and the cooling effects of different road cooling coatings were determined by means of a field test. The complex coupling environment of temperature, vehicle load, and pollution in the practical application of road cooling coating was simulated. Durability evaluation indexes of road cooling coatings under different composite operating conditions were presented, following which the comprehensive durability of different road cooling coatings was evaluated using a multi-objective grey target decision-making method. Road cooling coatings with superior comprehensive durability were selected. The results demonstrate that various road cooling coatings can reduce the asphalt pavement temperature under the impact of the outside environment. The comprehensive durability of road coatings is obviously improved with the addition of cooling function materials. [ABSTRACT FROM AUTHOR]

The snow- and ice-melting effect and energy usage of steel bridge deck pavement are affected by the heat-transfer rate and temperature change in the middle of the combination structure when using conductive gussasphalt concrete (CGA). To determine the heat conduction effect and the snow melting time of conductive gussasphalt concrete pavement, the heat conduction estimation method and a theoretical equation of the CGA combination structure are derived. A CGA combination structure with spreading carbon fiber in the middle of the CGA layer is prepared. The accuracy of the theoretical equation is checked and verified. Then, the heat conduction effect and the time required to reach and maintain the temperature above 0 °C of different CGA combination structures are evaluated. According to the estimation results and weather conditions, the power will be turned on or shut off ahead of time to improve the deicing efficiency and save energy. The results show that the theoretically obtained estimation values are close to the test values. The theoretical equation can estimate the heat conduction effect of the CGA combination structure. With a decrease in the environmental temperature, the time required for the surface temperature of different CGA combination structures to exceed 0 °C gradually increases, and the time required for the surface temperature to remain above 0 °C decreases. The surface temperatures of the CGA combination structure based on schemes 3 and 4 can be increased to above 0 °C in a short time and remain above 0 °C for a long time. [ABSTRACT FROM AUTHOR]

• The method of coating refractory bauxite in an organosilicon solvent. • The surface coating effects of different organosilicon solvents on high-alumina refractory bauxite. • The fundamental properties of different organosilicon–refractory bauxite materials. • The comprehensive performance evaluation of organosilicon–refractory bauxite based on the grey target decision-making method. The aim of this study is to improve the fundamental properties of refractory bauxite to promote its further application in the heat-resistant asphalt pavement technology. A method of coating refractory bauxite in an organosilicon solvent is proposed. The surface coating effects of different organosilicon solvents on high-alumina refractory bauxite are compared and evaluated using the macropore structure and the microsurface morphology. Based on the optimal treatment process and material proportion, the fundamental properties of different organosilicon–refractory bauxite materials are analyzed systematically. Based on the grey target decision-making method, the comprehensive performance of different organosilicon–refractory bauxite is evaluated. On this basis, the organosilicon–refractory bauxite material with better comprehensive performance was added into the asphalt mixture and its pavement performances were identified. The results show that a large number of pores of refractory bauxite are sealed by using organosilicon solvents. Moreover, the coating effect is good. In addition, the heat resistance is improved. The mechanical property and adhesion of refractory bauxite are increased by 30.66% and 66.67%, respectively. [ABSTRACT FROM AUTHOR]

[Display omitted] • A dataset of crushed ballast particles was prepared using single-particle crushing tests on 700 particles. • The crushed number and ballast particle size were predicted by machine learning classification and regression algorithms. • The validation of the proposed method is investigated using the discrete element modeling of ballast particles. Modeling the breakage of ballast particles is a key task for modeling the plastic deformation of ballast subjected to several loading cycles in DEM simulations. In this study, a series of single-particle crushing tests were performed on 700 ballast particles to specify the numbers and sizes of ballast particles crushed after ballast breakage. Four classification algorithms (support vector machine (SVM), backpropagation neural network (BPNN), random forest (RF), and CatBoost (CB)) were used to predict the number of particles crushed after ballast breakage. In addition, the particle sizes were estimated using the RF, SVM, BPNN, and eXtreme Gradient Boosting (XGB) regression algorithms. The initial particle size, shape, material, and loading conditions were considered variables for regression and classification. The dataset was divided into 75% and 25% as the training and test sets, respectively. The results indicated that CB and RF-based classification, with an accuracy of more than 91%, and RF and XGB based regression, with a normalized root-mean-squared error (NRMSE) of less than 0.08, appropriately estimated the number and sizes of crushed ballast particle. Moreover, the DEM simulation of ballast breakage using the particle bonded model (PBM) validated the values predicted using the machine learning models. The proposed method can be used to simulate ballast as bonded clumps instead of bonded pebbles with an acceptable breakage modeling accuracy. [ABSTRACT FROM AUTHOR]