Freeze-thaw Splitting Test Research Articles

Optimizing Thermosetting Epoxy Asphalt with Styrene–Butadiene Rubber and Styrene–Butadiene–Styrene Modifiers for Enhanced Durability in Bridge Expansion Joints

The high- and low-temperature performance of asphalt-based seamless expansion joints seriously affects road performance. The purpose of this paper is to explore the application of thermosetting epoxy asphalt-based materials in bridge expansion joints. The composite modification of asphalt was performed using Styrene–Butadiene rubber (SBR) and Styrene–Butadiene–Styrene (SBS) copolymer. The study then investigates the impact of five different dosages of SBR/SBS-modified asphalt on the performance of epoxy asphalt. The results of the cone penetration test, tensile test, and stress relaxation test of SBR/SBS-modified epoxy asphalt (SSEA) and BJ200 (a commercial Seamless expansion joint material) were comparatively analyzed. The Marshall test, rutting test, three-point bending test, and freeze–thaw split test were used to evaluate the road performance of SSEA mixtures. The test results show that with the increase in asphalt content, the shear resistance and tensile strength of SSEA decrease, and the low-temperature relaxation ability and elongation at break increase. The content of SBR/SBS-modified asphalt has a positive effect on the low-temperature performance of SSEA mixtures, and the residual stability in water and freeze–thaw splitting strength ratio (TSR) are higher than that of BJ200. Based on the requirement of balancing high and low-temperature performance, SSEA-3 has the best overall performance, and the dosage of SBR and SBS modifier is 12% and 2.5%, respectively. The ratio of epoxy resin, SBR/SBS-modified asphalt, and the curing agent is 1:4:1.6, and its use is recommended in areas with slight temperature differences.

Evaluation of SMA-13 Asphalt Mixture Reinforced by Different Types of Fiber Additives.

This research aims at systematically evaluating the properties of SMA-13 asphalt mixture reinforced by several fiber additives including flocculent lignin fiber (FLF), granular lignin fiber (GLF), chopped basalt fiber (CBF), and flocculent basalt fiber (FBF). Firstly, the thermal stability, moisture absorption, and oil absorption property of these fiber additives were analyzed. Secondly, the property of SMA-13 reinforced using four types of single fibers and two kinds of composite fibers (FLF + CBF and FLF + FBF) was comprehensively analyzed. Specifically, the high-temperature performance was evaluated using the uniaxial penetration test and the rutting test, the medium-temperature anticracking property was evaluated using the IDEAL-CT test, the low-temperature property was analyzed using the beam bending test, and the water stability was studied by the freeze-thaw splitting test. Thirdly, the dynamic mechanical response of different-fibers-modified SMA-13 was evaluated using the uniaxial compression dynamic modulus test. Finally, correlation analysis between the results of dynamic modulus and the high-, medium-, and low-temperature mechanical performance was carried out. The research results reveal that the stability of CBF and FBF under thermal action is better than that of GLF and FLF, and FBF shows the best thermal stability. The oil absorption property of FLF is better than that of GLF, followed by FBF and CBF. The comprehensive mechanical properties of CBF- and FBF-reinforced SMA-13 are better than those of FLF- and GLF-modified SMA-13. CBF can better reinforce the mechanical property of SMA-13 under low and medium temperature, while FBF can better reinforce the performance of SMA-13 at high temperature. FLF/CBF- and FLF/FBF-composite-modified SMA-13 show better high-temperature mechanical performance than that of the single-fiber-reinforced mixture, and FLF has some negative impact on the properties of FLF/FBF-composite-modified SMA-13 at low temperature. Fibers have no significant influence on the water stability of the mixtures. Meanwhile, the linear correlation between the mechanical performance of all the fiber-reinforced SMA-13 and the dynamic modulus result is good.

Influence of Basalt Fiber Morphology on the Properties of Asphalt Binders and Mixtures.

Basalt fiber (BF) has been proven to be an effective additive for improving the properties of asphalt mixtures. However, the influence of basalt fiber morphology on the properties of asphalt binders and mixtures remains inadequately explored. In this study, chopped basalt fiber (CBF) and flocculent basalt fiber (FBF) were selected to make samples for testing the influence of the two types of basalt fibers on asphalt materials. Fluorescence microscopy was used to obtain the dispersion of fiber in asphalt binders. Then, a temperature sweep test and a multiple stress creep recovery (MSCR) test were carried out to appraise the rheological characteristics of the binder. Moreover, the performance of the fiber-reinforced asphalt mixture was evaluated by a wheel tracking test, a uniaxial penetration test, an indirect tensile asphalt cracking test (IDEAL-CT), a low-temperature bending test, a water-immersion stability test, and a freeze-thaw splitting test. The results indicate that the rheological behavior of asphalt binders could be enhanced by both types of fibers. Notably, FBFs exhibit a larger contact area with asphalt mortar compared to CBFs, resulting in improved resistance to deformation under identical shear conditions. Meanwhile, the performance of the asphalt mixture underwent different levels of enhancement with the incorporation of two morphologies of basalt fiber. Specifically, as for the road property indices with FBFs, the enhancement extent of DS in the wheel tracking test, that of RT in the uniaxial penetration test, that of the CTindex in the IDEAL-CT test, and that of εB in the low-temperature trabecular bending test was 3.1%, 6.8%, 15.1%, and 6.5%, respectively, when compared to the CBF-reinforced mixtures. Compared with CBFs, FBFs significantly enhanced the elasticity and deformation recovery ability of asphalt mixtures, demonstrating greater resistance to high-temperature deformation and a more pronounced effect in delaying the onset of middle- and low-temperature cracking. Additionally, the volume of the air void for asphalt mixtures containing FBFs was lower than that containing CBFs, thereby reducing the likelihood of water damage due to excessive voids. Consequently, the moisture susceptibility enhancement of CBFs to asphalt mixture was not obvious, while FBFs could improve moisture susceptibility by more than 20%. Overall, the impact of basalt fibers with different morphologies on the properties of asphalt pavement materials varies significantly, and the research results may provide reference values for the choice of engineering fibers.

Assessing pavement characteristics: An in-depth evaluation of waste engine oil and Buton rock asphalt composite modified asphalt and its mixture

To investigate the cooperative influence of waste engine oil (WEO) and Buton rock asphalt (BRA) on asphalt characteristics, the WEO/BRA composite modified asphalt and its mixture with varied dosages were prepared. The high-, moderate-, and low-temperature assessments of WEO/BRA composite modified asphalt were conducted through temperature sweep tests, multiple stress creep and recovery (MSCR), and bending beam rheometer (BBR) tests. The softening point difference was used to analyze the storage stability of composite modified asphalt. Based on the Fourier transform infrared spectroscopy (FTIR) and fluorescence microscope (FM) test, the microscopic feature and chemical constitution of WEO/BRA composite modified asphalt were analyzed. Rutting test, low-temperature bending test, immersed Marshall test, freeze-thaw splitting test, and four-point fatigue bending test were carried out to verify the pavement properties of the WEO/BRA composite modified asphalt mixture. The results indicated that WEO improved the capability in low-temperature conditions and fatigue properties of asphalt modified with BRA. BRA enhanced the high-temperature property of asphalt modified with WEO. The synergistic effect of WEO, BRA, and neat asphalt was a physical reaction, and these modifiers were uniformly distributed in the asphalt. Meanwhile, WEO/BRA composite modified asphalt had excellent storage stability for the single modified asphalt. The test results of the asphalt mixture verified the results, indicating that WEO/BRA composite modified asphalt can be considered a new green and durable asphalt pavement material.

Performance Study of Asphalt Mixtures Reinforced with Gradated Basalt Fibers of Mixed Lengths

The length of basalt fibers affects the performance of asphalt mixtures. To explore the influence of different lengths of basalt fibers on the performance of asphalt mixtures, this study selected basalt fibers with lengths of 6 mm, 9 mm, and 12 mm to design gradations that were incorporated into asphalt mixtures to prepare specimens. High-temperature rutting tests, immersion Marshall tests, freeze-thaw splitting tests, and low-temperature splitting tests were conducted, resulting in 11 test mix designs and 12 test indicators. Then, a multi-objective grey target decision method was used to optimize the optimal combination ratio of basalt fiber lengths. The results indicate that compared to asphalt mixtures with single-length basalt fibers, incorporating well-combined basalt fibers significantly enhances the high-temperature, low-temperature, and water stability performance of asphalt mixtures. According to the grey target decision method, this study determined that a basalt fiber combination ratio of 3:4:3 for lengths of 6 mm, 9 mm, and 12 mm provides the best overall performance of asphalt mixtures. Additionally, when designing asphalt mixtures with graded basalt fibers, the inclusion of 9 mm fibers should be the primary control point. These research findings provide important guidance for the enhanced application of basalt fibers in road engineering.

Experimental Study on Pavement Performance of Warm High Modulus Mixture WHMM-13

In order to solve the dusting and rutting problems of hot mix asphalt mixture during construction and operation, rutting test, bending test, Marshall stability test, freeze-thaw splitting test, uniaxial compression dynamic modulus test, overlay test, and four-point bending fatigue life test are applied on WHMM-13 to study the high-temperature stability, low-temperature cracking resistance, water stability, anti-reflection crack performance and fatigue durability in comparison with HMM-13. The results show that, compared to HMM-13, the dynamic stability and dynamic modulus (45 ℃, 10 Hz) of WHMM- 13 are improved by 10.0% and 47% respectively, and the rutting depth is reduced by 27.3%, indicating that the high temperature stability of WHMM-13 has been greatly improved. As for low temperature cracking resistance, the bending failure strain, stiffness modulus, flexural tensile strength and rupture energy of WHMM-13 are slightly lower than those of HMM-13. As for water stability, the residual stability of WHMM-13 in immersion Marshall test is 87.5%, and the splitting strength is 82.3%, both higher than that of HMM-13. As for anti-reflection crack performance, the total tensile rupture energy of WHMM-13 is 2.32 times that of HMM-13, with cracking resistance index (CRI) increased by 25%, which shows that WHMM-13 has better strength, can effectively prevent the crack from spreading and effectively improve the cracking resistance capacity of asphalt pavement. As for fatigue durability, the fatigue life of WHMM-13 is 5.4% lower than that of HMM-13, with bending stiffness modulus and cumulative dissipation energy reduced by 11.3% and 2.8% respectively, indicating that the fatigue durability of WHMM-13 is slightly reduced.

Performance of Asphalt Mixtures Modified with Desulfurized Rubber and Rock Asphalt Composites

This study explores the performance of asphalt mixtures modified with North American rock asphalt and desulfurized rubber particles at varying rubber-to-asphalt ratios ranging from 18% to 36% by weight. A comprehensive set of laboratory tests, including high-temperature rutting tests, low-temperature bending tests, indirect tensile tests, and freeze–thaw splitting tests, were conducted to evaluate the modified mixtures. The results indicate that both wet and dry blending methods produce mixtures that meet technical requirements, with the optimal asphalt-to-aggregate ratio determined to be 7.1%. At a rubber-to-asphalt ratio of 18%, the wet blending method slightly improves high-temperature rutting resistance compared to the dry method. However, an increase in rubber content generally enhances rutting resistance regardless of the blending technique. The wet blending method excels in low-temperature crack resistance, possibly due to better rubber dispersion, while an increase in rubber content diminishes crack resistance due to a thinning asphalt film. In terms of fatigue performance, the dry blending method results in significantly longer fatigue life, with a 27% rubber-to-asphalt ratio exhibiting optimal balance. The dry method consistently outperforms the wet method in water stability, and the resistance to water damage increases with rubber content. In conclusion, this study provides valuable insights into optimizing rubber-to-asphalt ratios and blending methods for various application needs, showcasing the benefits of rock asphalt and desulfurized rubber particles in asphalt modification.

The Production of Porous Asphalt Mixtures with Damping Noise Reduction and Self-Healing Properties through the Addition of Rubber Granules and Steel Wool Fibers.

Conventional asphalt roads are noisy. Currently, there are two main types of mainstream noise-reducing pavements: pore acoustic absorption and damping noise reduction. However, a single noise reduction method has limited noise reduction capability, and porous noise-reducing pavements have a shorter service life. Therefore, this paper aimed to improve the noise-damping performance of porous asphalt mixture by adding rubber granules and extending its service life using electromagnetic induction heating self-healing technology. Porosity and permeability coefficient test, Cantabro test, immersion Marshall stability test, freeze-thaw splitting test, a low-temperature three-point bending experiment, and Hamburg wheel-tracking test were conducted to investigate the pavement performance and water permeability coefficients of the mixtures. A tire drop test and the standing-wave tube method were conducted to explore their noise reduction performance. Induction heating installation was carried out to study the heating rate and healing performance. The results indicated that the road performance of the porous asphalt mixture tends to reduce with an increasing dosage of rubber granules. The road performance is not up to the required standard when the dosage of rubber granules reaches 3%. The mixture's performance of damping and noise tends to increase with the increase of rubber granule dosage. Asphalt mixtures with different rubber granule dosages have different noise absorption properties, and the mixture with 2% rubber granules has the best overall performance (a vibration attenuation coefficient of 7.752 and an average absorption factor of 0.457). The optimum healing temperature of the porous asphalt mixture containing rubber granules and steel wool fibers is 120 °C and the healing rate is 74.8% at a 2% rubber granule dosage. This paper provides valuable insights for improving the noise reduction performance and service life of porous asphalt pavements while meeting road performance standards.

Mixing design and performance of porous asphalt mixtures containing solid waste

The process of urbanization generates substantial amounts of solid waste materials, including glass, red brick, concrete, and ceramic tile. Effective treatment methods for these waste materials are currently lacking, resulting in significant land wastage and environmental pollution. Utilizing these waste materials in the construction of asphalt pavements presents a viable solution for their high-quality and large-scale utilization. In this study, the properties of commonly produced urban solid waste materials, including glass, red brick, concrete, and ceramic tile, were investigated for their suitability as limestone porous asphalt mixtures. The physical and chemical properties of the coarse aggregate were examined using four groups of preliminary tests, including leakage analysis, scattering, rutting, and freeze-thaw splitting tests. The results revealed that the apparent relative density varied for different particle sizes within the range of 2.36–4.75 mm, 4.75–9.5 mm, 9.5–16 mm, and 13.2–16 mm. However, the dynamic stability of the glass specimen was only 740 times/mm, which falls significantly below the technical requirement of 1500 times/mm. Additionally, the high-temperature stability of the glass specimen was deemed unsatisfactory. The red brick test piece exhibited inadequate water stability due to its high-water absorption rate. Therefore, reducing the amount of waste glass and minimizing the incorporation of waste red brick are recommended. The findings of this study contribute to the expansion of application methods and techniques for urban solid waste, improving the utilization rate of solid waste resources. Furthermore, the study sheds light on the changes in the performance of solid waste aggregates mixed with porous asphalt mixtures, providing valuable insights for road engineering endeavors.

Research on the Prediction of Optimal Frequency for Vibration Mixing and Comparison on Initial Performance of Cold-Recycled Asphalt Emulsion Mixture.

The multicomponent cold-recycled asphalt emulsion mixture (CRAEM) has the ability of antireflection cracking between the base and the bottom surface layer, but it has secondary compaction and residual void, which is not conducive to crack resistance and fatigue performance. The application of high-frequency vibration mixing technology can reduce voids and improve crack resistance, but it is limited by the complexity of testing to determine the optimal mixing frequency. The fractal dimension of gradation is deduced by fractal theory, and the prediction model for optimal frequency is proposed. Dry, wet, freeze-thaw splitting tests, and rutting tests were employed to test the early mechanical properties of high-frequency vibration mixing specimens corresponding to different vibration accelerations, and mercury inclusion tests were utilized to compare the void distribution corresponding to the optimal mixing frequency and forced mixing, and to verify the prediction model for optimal frequency. The results indicate that the high-frequency vibration mixing technology is able to benefit the initial cracking resistance (28.1% increase), moisture stability (11.2% increase), and high-temperature stability on the macro level on the optimal frequency. Meanwhile, the void distribution structure can be optimized, reducing the proportion of harmful voids and increasing the proportion of transitional pores on the micro level. However, the freeze-thaw resistance needs to be further studied. This study reduces the number and cost of experiments to determine the optimal frequency, and provides theoretical guidance and technical support for the engineering application of the CRAEM.

Research on the Preparation and Performance of Biomimetic Warm-Mix Regeneration for Asphalt Mixtures

To determine the formula for biomimetic warm-mix regeneration and fulfill the requirements of a “high waste asphalt mixture content, high quality, and high level” for its usage in reclaimed asphalt pavement (RAP), this paper first determined the suitable preparation process and formula for biomimetic warm-mix regeneration based on orthogonal experiments and a gray correlation analysis. Then, the optimum dosage of the warm-mix regenerant was determined by a uniaxial penetration test, low-temperature splitting test, and freeze–thaw penetration test. The rutting test was conducted to characterize the high-temperature performance of the asphalt mixture. The Immersion Marshall Test and the freeze–thaw splitting test were used to characterize the water stability of the recycled asphalt mixture. The low-temperature small beam test was employed to study the low-temperature performance of the recycled asphalt mixture. The asphalt’s short-term and long-term aging processes were simulated using the rotary thin-film oven test (RTFOT) and the pressure aging test (PAV). The action mechanism of biomimetic warm-mix regeneration was revealed by Fourier-transform infrared spectroscopy (FTIR). Finally, a comprehensive thermal performance test was conducted on the aged asphalt after biomimetic warm-mix regeneration. The results showed that the self-made biomimetic warm-mix regeneration agent exhibited an excellent regenerative effect on RAP and significantly reduced the mixing temperature of the styrene–butadiene–styrene (SBS)-modified asphalt mixture. In addition, the self-made biomimetic warm-mix regeneration agent effectively improved the high- and low-temperature performance of the recycled asphalt mixture, but had no noticeable effect on the water stability. The suggested dosage of the biomimetic warm-mix regeneration agent was 6%, and the mixing temperature was 130 °C. The microscopic chemical analysis revealed that biomimetic warm-mix regeneration restored the performance of aged asphalt by supplementing the light component. The change rules of the chemical functional groups and the comprehensive thermal properties of the recycled mixture showed a good correlation with the change rules of its high- and low-temperature performance.

Research on the Road Performance of Ring Diamond Resin Modified Asphalt Mixture

In order to solve the problems of ineffective modification and high cost of most asphalt modifiers, a new type of high viscosity and high elasticity asphalt modifier - ring diamond resin is introduced, and this modifier is injected into 70 # base asphalt. Through high-temperature rutting, low-temperature bending, immersion Marshall and freeze-thaw splitting tests, the road performance of 70 # base asphalt and ring diamond resin modified asphalt mixture is compared and analyzed. Intended to improve the quality of asphalt pavement while reducing economic costs, thereby extending the service life of the road. The research results indicate that the ring diamond resin modifier can greatly improve the high-temperature performance of asphalt mixtures, and to a certain extent improve their low-temperature crack resistance and water stability. It is a resin modified material with great potential and high advantages. It is recommended to use a dosage of 1% in practical road engineering applications.

The stability of foamed asphalt concrete based on different soaking conditions

The purpose of this study is to test the water stability of foam asphalt mixture under various immersion conditions. For this purpose, experiments were conducted on warm mixed foamed asphalt and traditional hot mixed asphalt. To evaluate its water stability, Marshall tests, immersion Marshall tests, vacuum saturation Marshall tests, and freeze-thaw splitting tests were conducted. Based on surface energy theory, the water damage mechanism of asphalt mixtures was analyzed. The research results indicate that due to the adverse effects of water erosion and pressure, the water stability of the two mixtures gradually decreases. Although the failure load value of warm mixed foamed asphalt mixture is slightly lower than that of hot mixed asphalt mixture, its water stability parameters still meet the specified requirements. Therefore, warm mix foam asphalt mixture shows satisfactory water stability under different soaking conditions.

The Performance of Modified Asphalt Mixtures with Different Lengths of Glass Fiber

AbstractOne practical option for modifying an asphalt mixture’s performance is to use additives. This will help the mixture perform better against the damaging effects of traffic, loads, and climatic variations. In this regard, glass fiber (GF) has drawn much interest because of its positive effect. Therefore, this paper attempts to study the effect of glass fiber length and content on the performance and strength of asphalt mixtures. It also aims to determine the optimum glass fiber content and the best glass fiber length of modified asphalt mixtures. An experimental program is carried out, which includes the Marshall test, volumetric properties, freeze-thaw splitting test, immersion Marshall test, and wheel tracking test to characterize related properties of glass fiber incorporated in asphalt mixtures. Seven different percentages (0, 0.25, 0.5, 0.75, 1, 1.25, and 1.5) of glass fiber by total weight of aggregates in three various lengths are used to design 19 asphalt mixtures. Based on the results obtained, the performance of the asphalt mixture was enhanced remarkably after adding glass fiber. The use of various lengths of glass fiber led to a better-quality asphalt mixture in terms of volumetric properties, moisture damage resistance, and permanent deformation resistance. Specifically, asphalt mixtures made with (0.5%) glass fiber illustrated the highest quality, and adding (20 mm) length of glass fiber was better than (10 mm and 30 mm) glass fiber lengths. The results also show that adding (10 mm and 30 mm) lengths of glass fiber can improve the resistance of asphalt mixtures to water damage and permanent deformation compared with the control mixture (M0). The findings indicate the applicability of 20 mm glass fiber length in asphalt mixtures to achieve better resistance against moisture and reduce the chance of irreparable permanent deformation under growing traffic loads and hot climate changes. Although the inclusion of glass fiber in asphalt mixtures led to a modest increase (6%) in overall cost, the effective improvement in performance and extension of the service life of the asphalt pavement constitute a convincing argument for this approach, making it an attractive option. Finally, it was concluded that a higher amount of glass fiber (i.e., > 0.5%) and a length greater than (20 mm) could diminish the positive effect of glass fiber to improve the properties of glass fiber asphalt mixtures.

Rheological Properties of Silica-Fume-Modified Bioasphalt and Road Performance of Mixtures.

The objective of this research is to enhance the high-temperature antirutting and antiaging characteristics of bioasphalt. In this study, silica fume (SF) was selected to modify bioasphalt. The dosage of bio-oil in bioasphalt was 5%, and the dosage of SF was 2%, 4%, 6%, 8%, and 10% of bioasphalt. The high- and low-temperature characteristics, aging resistance, and temperature sensitivity of Bio + SF were evaluated by temperature sweep (TS), the multiple stress creep recovery (MSCR) test, the bending beam rheology (BBR) test, and the viscosity test. Meanwhile, the road behavior of the Bio + SF mixture was evaluated using the rutting test, low-temperature bending beam test, freeze-thaw splitting test, and fatigue test. The experimental results showed that the dosage of SF could enhance the high-temperature rutting resistance, aging resistance, and temperature stability of bioasphalt. The higher the dosage of SF, the more significant the enhancement effect. However, incorporating SF weakened bioasphalt's low-temperature cracking resistance properties. When the SF dosage was less than 8%, the low-temperature cracking resistance of Bio + SF was still superior to that of matrix asphalt. Compared with matrix asphalt mixtures, the dynamic stability, destructive strain, freeze-thaw splitting strength ratio, and fatigue life of 5%Bio + 8%SF mixtures increased by 38.4%, 49.1%, 5.9%, and 68.9%, respectively. This study demonstrates that the development of SF-modified bioasphalt could meet the technical requirements of highway engineering. Using SF and bio-oil could decrease the consumption of natural resources and positively reduce environmental pollution.

Investigation on the Performance of Modified Corn Stalk Fiber AC-13 Asphalt Mixture

As an agricultural waste, a large amount of corn stalk will cause environmental pollution. In order to realize the resource utilization of waste and meet the strict requirements of modern traffic on pavement strength and durability, it was modified and applied to an AC-13 asphalt mixture to study its influence on the road performance of asphalt mixture and its mechanism. The road performances of modified corn stalk fiber, lignin fiber, and ordinary asphalt mixtures were evaluated via the wheel tracking test, low-temperature bending test, water immersion Marshall test, freeze–thaw splitting test, and fatigue test. Based on the results of three-point bending fatigue test, the viscoelastic parameters and indexes of the fiber asphalt mixture were obtained by fitting the loading specimen and deflection data with the Burgers constitutive model, and the creep strain response was analyzed by applying dynamic load, so as to explore the relationship between the viscoelastic characteristics and creep behavior of modified corn stalk fiber and AC-13 mixture. The long-term high-temperature performance test of the asphalt mixture with the best fiber content was carried out by using the long-term pavement intelligent monitoring equipment independently developed by the group of investigators. According to the findings, the ideal fiber contents for modified corn and lignin in asphalt mixture are 0.2% and 0.3%, respectively. Among them, the modified corn stalk fiber with a 0.2% content has the best effect on road performance, viscoelastic performance, and the asphalt mixture’s creep behavior under dynamic load. Compared with the 0.3% lignin fiber asphalt mixture, its dynamic stability, bending stiffness modulus, immersion residual stability, freeze–thaw splitting strength ratio, and loading times at failure increased by 19.9%, 18.28%, 4.19%, 8.6%, and 9.15%, respectively. Compared with ordinary asphalt mixture, it increased by 47.0%, 28.72%, 7.65%, 15%, and 75.81%, respectively. Moreover, when modified corn stalk fiber is added at 0.2%, the viscoelastic delay time of asphalt mixture is the longest, the strain peak value and rut depth are at a minimum, and the viscoelastic properties, creep properties, and long-term high-temperature properties are the best.

Simulation study on basic road performance and modification mechanism of red mud modified asphalt mixture

Abstract In order to study the basic road performance and the mechanism of red mud modified asphalt, Marshall test, rut test, freeze-thaw splitting test, and immersion Marshall test were carried out for matrix asphalt mixture and red mud modified asphalt mixture, and molecular simulation technology was introduced to study the mechanism of red mud modified asphalt. The results showed that the penetration rate of red mud modified asphalt was lower than that of the matrix asphalt, and the softening point of asphalt was significantly improved after the addition of red mud, and the mixing of red mud reduced the asphalt ductility greatly. The intensity ratio (test strength ratio; TSR) of the freeze-thaw test of red mud modified asphalt under 3, 5, 7, 9, and 11% was increased by 13.18, 11.22, 13.54, 12.01, and 8.45%, respectively, compared with the matrix asphalt mixture, and the dynamic stability value increased by 127.23, 176.87, 200.99, 96.23, and 12.95%; the residual stability value of the immersion Marshall test increased obviously. Generally, the research of red mud modified asphalt is quite worthy, it can solve the problem of aluminum ore slag and reuse of resources, and provide a new way to extend the industrial chain.

Design and evaluation of semi self-compacting cold mix polyurethane mixture for steel bridge deck pavement

To enhance the environmental sustainability and pavement performance of steel bridge deck paving, a novel semi self-compacting cold mix polyurethane mixture (CMPU-10) for steel bridge deck paving was specifically designed and evaluated. Herein, this study presents the first comprehensive documentation of the research process involved in the mix design of CMPU-10. Initially, based on the theory of maximum density curve, a gradation with a Talbot index (n) of 0.40 was identified as the preliminary gradation for designing CMPU-10 by void ratio, compressive strength and slump tests. Subsequently, the aggregate grade-by-grade filling test revealed the critical influence of sieve sizes (0.075 mm, 0.6 mm, and 2.36 mm) on the mixture dense degree. From these findings, an in-depth analysis of the effects of aggregate passage under the key sieve on the degree of mixture density, compressive strengths, and flow properties led to the determination of the gradation range of CMPU-10. The optimum binder-aggregate ratio for the median gradation was determined to be 9.2%. Finally, wheel tracking, semi-circular bending (SCB) and freeze-thaw splitting tests showed that the designed CMPU-10 exhibits superior high-temperature stability performance, low-temperature cracking resistance and moisture susceptibility compared to the TAF epoxy asphalt mixture (EA-10). This paper not only provides a new potential low-carbon material for steel bridge deck paving projects, but also establishes a theoretical foundation for the optimization design and promotion polyurethane mixture.

Road Performance and Self-Healing Property of Bituminous Mixture Containing Urea-Formaldehyde Microcapsules.

Urea-formaldehyde (UF) is a common shell material for self-healing microcapsules; however, the influence of urea-formaldehyde microcapsules (UFMs) on the road performance of bituminous mixtures and the sensitivity of their healing abilities remains unclear. In this paper, UFMs were prepared via in situ polymerization (ISP), followed by an investigation into the road performance of UFM self-healing bituminous mixtures through various tests, including wheel tracking, immersed Marshall, freeze-thaw splitting, low-temperature bending, and three-point bending fatigue tests. Subsequently, the impact of the damage degree, healing duration, and temperature on the self-healing property was discussed. The results indicated that incorporating 3 wt% UFMs into bitumen significantly improved the high-temperature stability and fatigue resistance of the bituminous mixture; for example, its dynamic stability and fatigue life could be increased by about 16.5% and 10%, respectively. However, it diminished the thermal crack resistance, as evidenced by decreases in bending tensile strength and strain by 3.7% and 10.1%, respectively. And it did not markedly improve the moisture susceptibility. Additionally, the maximum improvement observed in the healing rate was about 9%. Furthermore, the healing duration and temperature positively influenced the bituminous mixture's self-healing, whereas the degree of damage exerted a negative impact, with a relatively significant effect.

Design of High-Modulus Asphalt Concrete for the Middle Layer of Asphalt Pavement

This article investigates the application of high-modulus asphalt mixtures (HMM-13) in the intermediate layer of pavement, addressing rutting issues in asphalt pavements subjected to heavy traffic and high temperatures. The study utilized a 1% dosage of high-modulus modifier, and initially, the mix design of HMM-13 was determined using the gyratory compaction method. Subsequently, this study evaluated the road performance of HMM-13 through tests, including the −10 °C beam bending test, rutting tests at 60 and 70 °C, the freeze–thaw splitting test, and the single-axis compression dynamic modulus test. To ensure the effectiveness of the mixture’s on-site application, this study validated the raw material specifications at the construction site and adjusted the mix design accordingly. Water stability tests were also conducted. Finally, a survey of the mixing plant at the construction site was carried out, establishing the relationship between each bin’s flow rate and speed ratio. The suitable speed for the production of HMM-13 was calculated. The research results indicate that the optimal asphalt-to-aggregate ratio for HMM-13 is 4.2% (with a comprehensive asphalt-to-aggregate ratio of 5.2%), and the freeze–thaw splitting strength ratio can reach 84.2%. The dynamic stability is 11,217 cycles/mm at 60 °C and 6167 cycles/mm at 70 °C. The stiffness modulus at −10 °C is 5438 MPa, with a failure strain of 2049 με. At 10 Hz and 15 °C, the dynamic modulus is 15,488 MPa, and at 45 °C, it is 3872 MPa. All these indicators meet the requirements for construction technology and pavement performance.