Search Results (29)

The behavior of the cast-in-place continuously reinforced concrete (CRC) bus pad applied to bus stop pavement in a central bus-only lane was experimentally analyzed under environmental and moving vehicle loads, and the early-age performance of the CRC bus pad was evaluated using experimental data and finite element analysis results. Using various measurement sensors, the concrete slab strain, longitudinal steel bar strains, horizontal and vertical displacements, and crack behavior of the CRC bus pad due to environmental loads were measured, and the dynamic responses of the concrete slab and steel bars due to moving vehicle loads were also measured. Additionally, a method for converting strain gauge measurements of a cracked concrete slab to the strain of an uncracked concrete slab was also proposed. Under environmental loads, the range of stresses acting on the steel bars and the bond between concrete and steel bars were analyzed to be appropriate for ensuring excellent performance of the CRC bus pad. The crack widths and vertical and longitudinal displacements of the CRC bus pad were found to have no effect on the pavement performance. Within the vehicle velocity range used in this experiment, the strains of the slab and steel bars as the vehicle passed through the CRC bus pad were virtually independent of the vehicle velocity and were within a range that did not cause any reduction in pavement performance. This study confirmed that the CRC bus pad has excellent performance and can replace asphalt concrete bus stop pavement or jointed concrete bus pad. Full article

This study evaluates the feasibility of reusing steel slag aggregates in asphalt concrete, analyzing the impact of different gradation methods (Bailey method and conventional Brazilian method) on the mechanical properties of the mix. Using the Marshall methodology and Petroleum Asphalt Concrete (PAC) 30/45, parameters such as Marshall stability, indirect tensile strength, resilient modulus, fatigue life through diametral compression, and permanent deformation (Flow Number) were investigated. Additionally, a simulation for a hypothetical section in the city of Rio de Janeiro, Brazil, was performed using the mechanistic-empirical pavement design software, Medina. The results showed that the mixture produced by the Bailey method outperformed the others in all analyses. This method led to a more compact mix, providing significant advantages, including up to a 35% reduction in final pavement thickness and a 110.6% increase in Flow Number (FN), enabling the mix to withstand extremely heavy traffic, as reported in the literature. Regarding fatigue life, the Bailey mixture achieved a fatigue class of 4, compared to the conventional mixture class 1. These findings indicate that using the Bailey gradation method for producing asphalt mixtures with steel slag can optimize binder content and improve resistance to permanent deformation and fatigue, making it a viable and sustainable alternative for asphalt pavements. Full article

In this study, the practical application of self-healing asphalt mixtures incorporating steel wool fibers and induction heating was investigated, expanding upon previous research that primarily assessed the self-healing properties rather than optimizing the heating process. Specifically, the aim was to enhance the induction heating methodology for a semi-dense asphalt concrete mixture (AC 16 Surf 35/50 S). In this research, the induction heating parameters were refined to improve the self-healing capabilities, focusing on the following three key aspects: (i) energy consumption, (ii) heating rate, and (iii) heating homogeneity. The findings reveal that the current intensity, the percentage of ferromagnetic additives, and coil shape are critical for achieving optimal heating conditions. Higher current intensity and additive percentage correlate with improved heating speed and reduced energy consumption. Additionally, variations in coil shape significantly influence the heating uniformity. Although asphalt mixtures with steel slag coarse aggregates exhibit slightly higher specific heat, this aggregate type is preferable for sustainability, as it allows for the recycling of industrial waste. The optimized mixtures can rapidly reach high temperatures, facilitating effective crack repair. This innovation offers a durable, environmentally friendly, and cost-effective solution for road maintenance, thereby enhancing the longevity and performance of asphalt pavements. Full article

In recent years, fatigue cracking in orthotropic steel bridge deck pavements has become a significant concern, so the investigation of the mechanical response of the pavement layer has become a central focus in pavement structure design. This experiment subjected a full-scale specimen to a constant amplitude dynamic load of 60 kN to 300 kN over 2 million cycles. Throughout the testing, a circulating water bath elevated the temperature of the pavement layer from 15 °C to 50 °C. Key locations were monitored for strain and deflection data, facilitating an investigation into the mechanical response of the epoxy asphalt pavement system under the effects of temperature and load. The results indicate that the maximum transverse strain at the bottom of the steel deck occurs at the U-rib weld aligned with the load center, reaching 190% of the initial loading strain. Meanwhile, the maximum transverse strain on the pavement surface is observed at the U-rib weld adjacent to the loaded area, measuring 167% of the initial strain. The maximum longitudinal strain is lower than the maximum transverse strain. In the load zone, the longitudinal strain between the U-ribs exceeds that at the U-rib weld. Both transverse strain and relative deflection increase as the load intensifies. The relationship between transverse strain and applied load is characterized by an exponential function, while deflection exhibits a cubic relationship with the applied load. Elevated temperatures also contribute to increased transverse strains at both the bottom of the steel deck and the pavement surface, following an exponential trend. Relative deflection is primarily influenced by the applied load and remains relatively unaffected by temperature variations. When accounting for the coupling of load and temperature, the maximum transverse strains at both the bottom of the steel deck and the pavement surface can be modeled as an exponential function of the independent variables: load and temperature. Full article

The decks of steel–concrete composite bridges are constantly exposed to severe environmental conditions, which frequently give rise to significant issues, including cracks and holes. These problems occur due to the formation of blisters under the paving layer with waterproofing membranes. This paper aims to delve into the characteristics of blisters during their expansion and propagation stages. Additionally, it proposes a rating index and a simplified calculation formula to assess the interface propagation performance of bridge deck pavement. To achieve this, the research group developed a simulated blister test device and employed the digital image correlation (DIC) technique. The study investigated the impact of pavement structure, waterproofing layer, and air voids on blister propagation behavior. It was discovered that the pavement blister test encompassed two distinct stages: expansion and propagation. Furthermore, the SMA-13 asphalt mixture exhibited slightly superior resistance to blistering compared to AC-13. It was also observed that when the mixture void ratio is less than 3.5%, it becomes more susceptible to blistering deformation, ultimately leading to debonding damage. Among the waterproofing materials tested, SBS-modified emulsified asphalt demonstrated the weakest adhesion to cement concrete substrates, while SBS-modified asphalt performed slightly better than rubberized asphalt. Full article

The paving layer on the steel box girder bridge deck is widely used when constructing pavements for steel bridges. Owing to the orthotropic feature of steel decks, a transverse clapboard and rib can lead to a concentration of stress. Consequently, fatigue cracks are often identified in asphalt concrete pavement layers due to re-compaction caused by heavy vehicles. This study aims to derive an evaluation method of fatigue life for asphalt pavement based on the inhomogeneous Poisson stochastic process in view of the highly random and uncertain working conditions of layered composite structures. According to the inhomogeneous Poisson stochastic process, along with Miner’s fatigue damage accumulation theory and the linear elastic fracture mechanics theory, the fatigue life formula could be deduced. Meanwhile, fatigue experiments for asphalt concrete are designed to investigate the correlation between the theoretical formula and the actual fatigue damage life of the material. Compared with the test, the accuracy error is within 10%, which is better than other traditional methods. Therefore, the fatigue life prediction model could better reflect the loading order effect and the interaction between loads, providing a new path for the fatigue reliability design of steel bridge deck asphalt pavement. Full article

To realize the application of epoxy asphalt concrete on roads and solve the problem of the high cost of epoxy asphalt concrete and the causes of bulging in the construction process, a low-content epoxy asphalt mixture was experimentally studied. Rheological and microscopic tests were carried out to study its performance. At the same time, 17 kinds of low-content asphalt mixture Marshall test pieces and rut plate test pieces with different oil stone ratios were made. Their road performances were tested, and a watertight breathable epoxy asphalt mixture was studied to solve the bulging problem. The research shows that, for ordinary roads, a content of epoxy resin of 10–15% can meet both the high-temperature and the low-temperature requirements. For sections with special rutting resistance requirements, a controlled epoxy resin content between 15 and 30% is recommended. When the content of epoxy resin is greater than 30%, epoxy asphalt initially forms a crosslinked spatial network. An epoxy asphalt with a complex structure from asphaltene to epoxy, with ultra-high performance, can be used for small steel bridge pavements. A BBR test showed that, with an increase in epoxy resin content, the low-temperature performance of asphalt gradually weakens. When the content was 20%, epoxy asphalt’s low-temperature performance was weaker than that of SBS-modified asphalt. Under extremely low-temperature conditions, the performance of epoxy asphalt could not meet the specifications. When the voids of low equivalent epoxy asphalt mixture are controlled at 4.1–4.5%, it is watertight and breathable; this can solve the problem of bulging and greatly reduce the cost of projects. Full article

One of the most roller cement concrete pavement failures of pavement is the formation of first cracks. The roughness of its completed surface after the installation has restricted the usage of this pavement. Therefore, engineers increase the quality of service of this pavement by placing a layer of asphalt coating; The primary goal of this study is to evaluate the impact of particle size and type of chip seal aggregates on filling cracks in rolled concrete pavement. Accordingly, rolled concrete samples with chip seal covering were prepared with various aggregates (limestone, steel slag, and copper slag). Then, the influence of temperature on its self-healing ability was tested by putting the samples in the microwave device for cracking improvements. With the aid of Design Expert Software and image processing, the Response Surface Method reviewed the data analysis. Even though due to the study’s limitations, a constant mixing design was applied, the results of this study indicate that the amount of crack filling and repair in specimens slag is higher than that of aggregate materials. With the increase of steel and copper slag, 50% of repair and crack repair at 30 °C, the temperature is 27.13% and 28.79%, respectively, and at 60 °C, the temperature is 58.7% and 59.4%, respectively. Full article

Although the double-layer pavement structure with a top layer of stone mastic asphalt concrete (SMAC) and a bottom layer of epoxy asphalt concrete (EAC) has been confirmed to have excellent overall performance in the laboratory, there is a lack of comparison and verification in practical projects. Hence, the utilization of the SMAC + EAC structure in this steel bridge deck pavement (SBDP) practical project and the clarification of its service performance are of significant importance for facilitating the promotion and application of this novel structure. This study relied on an SBDP reconstruction project in Ningbo, China. Indoor performance tests were used to determine the appropriate material compositions for SMAC and EAC. Subsequently, both ERS and SMAC + EAC pavement structures were paved in the project, and the service conditions of the different pavements after one year of operation were tested and compared. The results indicated that the epoxy SBS asphalt (ESA) binder prepared by substituting SBS-modified asphalt binder for the base binder, exhibited improved mechanical strength and toughness. The variation of modifier content significantly affected the high-temperature stability, low-temperature crack resistance, and moisture damage resistance of epoxy SBS asphalt concrete (ESAC) and high-viscosity SBS asphalt concrete (HSAC), while the gradation mainly influenced the skid resistance. The optimal contents of modifiers in ESA and HAS binders were finalized at 45 wt% and 11 wt%. After one year of operation on the trial road, the pavement performance of the SMAC + EAC structure had significant advantages over the ERS system, with all lanes having an SBDP quality index (SDPQI) above 90 and an excellent service condition. The successful application of the SMAC + EAC structure validated its applicability and feasibility in SBDP, which provided strong evidence for the further promotion of this structure. Full article

Suitable evaluation of distress is beneficial to understanding the in situ performance of deck pavement. This study attempts to evaluate the long-term in situ performance of American ChemCo epoxy asphalt concrete on the Xihoumen Bridge (XHMB) after 12 years of service. The traditional performance indexes were adopted to reveal the performance of XHMB. Then, based on the typical distresses, a new pavement performance index (PPI) was proposed to characterize the authentic distress condition. Finally, the performance evaluation and evolution were conducted. According to the results, the rutting depth indexes and riding quality indexes of all lanes are higher than 97 and 94, respectively. The pavement condition indexes of the pass lanes and drive lanes in 2021 are greater than 94 and 86, respectively, which is contradictory to the distribution of numerous distresses on the pavement. According to the PPI results, the PPIs of the down direction pass lane are mostly 100. However, for the down direction drive lane, the PPIs of about 30% of segments are below 80 or 60. Finally, based on the limited data, the distress of American ChemCo epoxy asphalt concrete may initiate after serving for 4–5 years and then escalate after about 10 years. Full article

In order to obtain the optimal electrode layout and ice melting effect of cast conductive asphalt concrete steel bridge deck pavement, firstly, pouring conductive asphalt concrete was prepared; secondly, different electrode materials and layout methods were selected to test the heating rate of the specimen from start to 120 min, and the electrode materials and layout methods were optimized. Then, the finite element analysis software ANSYS was used to build the model for heating and ice melting simulation, and the indoor test was used to further verify the ice melting effect of the cast conductive asphalt coagulation with or without the insulation layer. Finally, the thermal-structural coupling analysis of cast conductive asphalt concrete steel bridge deck pavement was carried out using ANSYS finite element software. The results showed that the stainless steel electrode material had the best heating effect, and the electrode thickness in the range of 0.1~3 mm had no effect on the heating effect. The intermediate heating rate of the upper surface of the stainless steel sheet electrode cast conductive asphalt concrete in the left and right external electrodes was 8 ${}^{\circ }$C/h, while the intermediate heating rate of the upper surface of the stainless steel mesh electrode cast conductive asphalt concrete was 12.9 ${}^{\circ }$C/h. The layout of the left and right buried stainless steel metal mesh was able to effectively improve the snow melting efficiency; ANSYS finite element ice melting simulation was used to obtain the variation law of ice melting efficiency and a temperature field of cast conductive asphalt concrete. The indoor ice melting test showed that when melting the same thickness ice layer at 50 V voltage, it took 240 min with an insulation layer and 720 min without an insulation layer, which was three times that of the ice with an insulation layer, which further verifies the superiority of its ice melting effect. The most unfavorable load position of pavement under load and temperature field was determined. The maximum tensile stress and compressive stress of the pavement surface were transverse, and the maximum shear stress of the pavement bottom was transverse. Full article

Various researchers are developing efforts to integrate waste and by-products as alternative materials in road construction and maintenance, reducing environmental impacts and promoting a circular economy. Among the alternative materials that several authors have studied regarding their use as partial or total substitutes for natural aggregates in the asphalt paving industry, the steel slag aggregate (SSA) and recycled concrete aggregate (RCA) from construction demolition waste (CDW) stand out. This paper reviews and discusses the characteristics and performance of these materials when used as aggregates in asphalt mixtures. Based on the various studies analyzed, it was possible to conclude that incorporating SSA or RCA in asphalt mixtures for road pavements has functional, mechanical, and environmental advantages. However, it is essential to consider some possible drawbacks of these aggregates that are discussed in this paper, to define the acceptable uses of SSA and RCA as sustainable feedstocks for road paving works. Full article

The bonding between pavement and a steel bridge deck is a key component affecting the structural integrity of steel deck pavement and delamination is a major cause. The bonding interface of steel deck pavement was systematically investigated to evaluate the interactive influences of factors, such as the air void of the asphalt concrete pavement, the surface roughness of the steel deck, the thickness of the zinc-rich epoxy primer, and the waterproof bonding membrane, on the bond strength of the pavement interface, through simulated loading, brine immersion, pull-off, and interface observation experiments. The results show that a low air void (<3.0%) was a necessary condition for the corrosion resistance and bonding reliability of the steel deck pavement structure, and a zinc-rich epoxy primer provided an additional guarantee for corrosion resistance of the steel deck pavement; additionally, the combination of steel deck plate roughness in the range of 120–140 μm and zinc-rich epoxy primer thickness in the range of 80–110 μm led to a high bond strength, which was also conducive to the corrosion resistance of the steel bridge plate. The steel deck pavement structure should be designed through combinatorial optimization of multiple factors to create an integrated waterproof and anticorrosion bonding system. Full article

Asphalt concrete pavements are vulnerable to freeze-thaw cycles. Consecutive cracking and penetration of corrosive agents can expedite the degradation of asphalt pavements and result in weight loss and reduced strength. Fiber reinforcement in flexible bituminous asphalt bridge cracks limits the crack width and enhances the toughness of the composite. Furthermore, steel fibers facilitate asphalt heating during maintenance and repair operations. Electrical resistivity is a vital parameter to measure the efficiency of these operations and to identify the state of degradation in fiber-reinforced asphalt concrete. The significant difference between conductivities of steel fibers and bituminous matrix warrants in-depth investigations of the influence of fiber reinforcement on the measured surface electrical resistivity of placed pavements. Numerical simulations endeavor to predict the resistivity and associated deviations due to randomly distributed fiber reinforcement. Results and discussions reveal the sources and magnitudes of fiber geometry and content adjustments. Outcomes investigate associated errors for practical applications. Full article

Aiming at the problem that orthotropic steel bridge deck and bridge deck pavement are prone to fatigue damage, Engineered Cementitious Composites (ECC) bridge deck pavement is used to replace concrete or asphalt in flexible bridge deck pavement. In order to deeply explore the shear resistance of the short stud interface in the ECC–steel composite structure and provide theoretical support for the practical application of the project, 16 static push-out tests were completed. The effects of stud diameter, height and arrangement spacing on the shear capacity of the medium and short ECC studs were studied. The failure modes, load–slip curves, load–strain curves and interface gap width curves of the components were analyzed. The test results showed that the shear force of the medium and short ECC bolts mainly produces two failure modes, bolt shearing and bolt root weld shearing, while the ECC plate has a local crushing area at the interface bolt root position, and no large cracks occur in other areas. The shear capacity of short bolts is significantly affected by the diameter of the bolts, but is less affected by the height and spacing of the bolts, and increases with the diameter of the short bolts. The length of the stud has an important influence on the stress on the surface of the ECC board. The longer the stud, the greater the tensile stress on the ECC surface. The shorter the peg, the more prone to eccentric compression the ECC plate is, and the longer the peg, the more prone to axial compression it is. Full article