Search Results (19)

To address the deficiencies of traditional emulsified asphalt-pavement maintenance material in cohesive strength, high-temperature rutting resistance, as well as adhesion to aggregates, this study developed waterborne epoxy resin-modified emulsified asphalt (WEA) binders using a two-component waterborne epoxy resin (WER) and systematically investigated their modification mechanisms and pavement performance. The results indicated that WER emulsions and curing agents could polymerize to form epoxy resin within the emulsified asphalt dispersion medium, with the modification process dominated by physical interactions. When the WER content exceeded 12%, a continuous modifier network structure was established within the emulsified asphalt. The epoxy resin formed after curing could significantly increase the polarity component of the binder, thereby increasing the surface free energy. The linear viscoelastic range of the WEA binder exhibited a negative correlation with the dosage of the WER modifier. Notably, when the WER content exceeded 6%, the high-temperature stability (rutting resistance and elastic recovery performance) of the binder was significantly enhanced. Concurrently, stress sensitivity and frequency dependence gradually decrease, demonstrating superior thermomechanical stability. Furthermore, WER significantly enhanced the interfacial interaction and adhesion between the binder and aggregates. However, the incorporation of WER adversely affects the low-temperature cracking resistance of the binder, necessitating strict control over its dosage in practical applications. Full article

High Friction Surface Treatments (HFSTs) are frequently used to increase skid resistance and reduce collisions, particularly in crash-prone zones, including horizontal curves and intersections. Epoxy-based binders traditionally have been the sole option for HFSTs, but their drawbacks, such as high costs and compatibility challenges, have led to the search for substitute binders, including asphalt-based options. This study investigates the comparative performance of highly modified asphalt-based binders, including polymer-modified, mastic, and highly modified emulsions, in HFST applications using two aggregate types, Calcined Bauxite (CB) and Rhyolite with different gradations, with an emphasis on their frictional properties, durability, and resistance to polishing. Laboratory evaluations, including the Pendulum Tester (BPT), Dynamic Friction Testing Equipment (DFT), Surface Texture Measurement Apparatus (CTM), and Binder Bond Strength Test (BBS), were carried out to examine the Coefficient of Friction (COF), Mean Profile Depth (MPD), and aggregate bonding and retention. In terms of durability and friction, this study indicated that highly modified asphalt-based binders performed better than PG binders and conventional emulsions. The highest BPT values, both prior to and following polishing, were consistently observed for CB, with the emulsion containing the highest reactive polymer modifier showing the smallest decrease in BPT value (12.86% for CB and 10.34% for Rhyolite). Epoxy showed a greater COF retention over lengthy polishing cycles; however, highly polymer-modified (PM) binders like PG82-22 (PM) performed better than Epoxy under specific conditions. The macrotexture analysis revealed that Epoxy-based samples retained surface texture for further polishing cycles, while Mastic2 and PG82-22 (PM) also showed strong MPD retention. These findings highlight the importance of optimizing aggregate–binder combinations to ensure durable and effective HFST applications. Full article

Epoxy asphalt, as a thermosetting and thermoplastic polymer composite material, has been widely used for steel bridge decks and specialty pavements due to its road performance, thermal stability, rutting resistance, and durability. However, the poor compatibility between epoxy resin binder and asphalt, due to the difference in chemical structure, polarity, and solubleness, severely restricts their practical applications in the construction of bridges and roads. Herein, we proposed a facial method to strengthen their compatibility by blending the poly(styrene-butadiene-styrene)-modified carbon nanotubes (SBS-CNTs) in the composite. The SBS-CNTs were found to evenly disperse in epoxy asphalt matrix with the epoxy resin contents of 10%–30% and could form the three-dimensional bi-continuous cross-linked structure at 30%. Moreover, the addition of epoxy resin increased the glass transition temperature (Tg) and enhanced the high-temperature shear capacity and tensile strength (over an order of magnitudes) of SBS-CNT-modified asphalt, which showed high potential for applications in the construction of bridges and roads, providing an alternative approach for improving the performance of epoxy asphalt. Full article

In order to improve the reclaimed asphalt pavement (RAP) dosing and the road performance of recycled asphalt mixtures, this study prepared epoxy recycled binder (ERB) and epoxy recycled mixtures (ERMs) by dosing epoxy asphalt, respectively. The rheological characteristics and microstructure of ERB were comprehensively analyzed using a dynamic shear rheometer (DSR), a bending beam rheometer (BBR), and fluorescence microscopy (FM). The road performance of ERM was evaluated by a four-point bending test, a rutting test, trabecular beam bending test, a freeze–thaw splitting test, an immersion Marshall test, and a uniaxial compression dynamic modulus test. Grey relational analysis (GRA) was used to quantify the correlation between the dosage of epoxy system and road performance indicators. The results show that, after the addition of the epoxy system, the high- and low-temperature rheological properties of ERB were improved by 458.3% and 97.9% compared with those of ordinary asphalt, and the high-temperature performance and fatigue performance of ERM were improved by 220.4% and 80.5% compared with SBS-modified asphalt mixtures. The dynamic modulus test showed that the dynamic modulus of ERM was positively correlated with the dosage of epoxy system. GRA showed that the dosage of epoxy system was most closely related to the fatigue performance of recycled mixtures. Full article

A fast-melting epoxy resin styrene–butadiene–styrene composite modifier (ER-SBS-T) was utilized for the rapid modification of an asphalt binder. The effect of this novel fast-melting modifier on high-temperature performance is not supported by any pertinent investigations. First, the penetration, softening points, and 60 °C kinematic viscosity of the asphalt samples were tested. In addition, these asphalt samples were subjected to multiple stress creep recovery (MSCR) tests to assess the ability to recover from creep and to test the high-temperature performance of the asphalt binder. The study then compared different models based on the zero-shear viscosity (ZSV) test. The research shows that the use of ER-SBS-T composite modifiers significantly improves the high-temperature performance of asphalt binder. The high-temperature performance of fast-melting SBS-T-modified asphalt binder is comparable to that of SBS-modified asphalt binder. The high-temperature performance of the asphalt binder can still be significantly improved when the amount of ER-SBS-T composite modifier exceeds 6%. For the high-temperature performance grading of the ER-SBS-T composite-modified asphalt binder, a reference temperature of 70 °C can be established. The results also demonstrate that the Cross rheological model is more suitable for determining the zero-shear viscosity of the ER-SBS-T composite-modified asphalt binder. Full article

Existing research shows that using waterborne epoxy resin (WER) instead of emulsified asphalt as the binder for cold mix asphalt (CMA) can enhance the rutting resistance, high-temperature performance, fracture performance, and early performance of CMA. In order to eliminate the potential drawbacks such as insufficient strength and low-temperature performance of CMA during application, a novel method was proposed in this study for the preparation of waterborne epoxy-acrylate resin (WER), specifically tailored to modify emulsified asphalt, resulting in waterborne epoxy-acrylate resin emulsified asphalt (WEREA). The modification effect of WER on emulsified asphalt was evaluated through rheological tests and direct tensile tests. A modified design method based on the conventional Marshall design method was proposed to determine the optimal mix proportions, including the key parameters of specimen compaction and curing. The results revealed that the incorporation of WER led to a substantial improvement in the complex shear modulus and a concurrent decrease in the phase angle. When the temperature exceeded 60 °C, the phase angle exhibited a diminishing trend, indicative of a reduced viscosity as temperatures escalated. As the WER content increased, a decrease in the direct tensile strain rate was observed, accompanied by a substantial elevation in direct tensile strength. At various stress levels, the shear strain of WEREA decreases with increased content of WER, indicating that the incorporation of WER can enhance the hardness of emulsified asphalt and improve its deformation resistance. The results from MSCR tests indicate that WER could significantly improve the elasticity and hardness of emulsified asphalt, transitioning it from a viscoelastic material to an elastic material, thereby improving its deformation resistance, resistance to rutting, and high-temperature performance. The results of fatigue life are consistent with those of the amplitude sweep, both reflecting the improvement of resistance to deformation of emulsified asphalt by WER. This indicates that WER has a significant improving effect on the fatigue resistance of emulsified asphalt. Furthermore, the Marshall design tests further confirmed the advantages of WEREA in asphalt mixtures. The optimal preparation for the WEREA mixture was proposed as follows: double-sided compaction for 50 times each, aging at 60 °C for 48 h, optimal moisture content of 5.14%, cement content of 2.5%, and emulsion content of 8.4%. The optimal mix proportions identified through these tests yielded asphalt mixtures with significantly improved stability, reduced flow value, and enhanced rutting resistance compared to the hot-mix asphalt mixture (HMA) of AC-16. These findings suggest that WEREA has the potential to significantly enhance the durability and longevity of asphalt pavements. For future applications, it can be explored for use in producing cold recycled asphalt mixtures. In addition to designing the WEREA mixture according to AC-16 gradation, consideration can also be given to using a gradation with a smaller nominal maximum aggregate size for the application in the surface layer or ultra-thin wearing course. Full article

The regeneration performance of an aged styrene–butadiene–styrene block copolymer (SBS) will be significantly influenced by different rejuvenators. The objective of this study was to comparatively investigate the regeneration effect of different SBS-modified asphalt regenerators on aged SBS-modified asphalt. Four types of different regenerant formulations were selected. The optimal rejuvenator content was determined firstly using conventional performance tests. The rheological properties of the aged SBS-modified asphalt binder were evaluated by multiple stress creep recovery (MSCR) experiments. Subsequently, the regeneration mechanism of the SBS-modified asphalt binder was investigated using thin-layer chromatography–flame ionization detection (TLC-FID) and Fourier transform infrared spectroscopy (FTIR). The results showed that the rejuvenator had a certain recovery effect on the penetration, softening point, and ductility of the SBS-modified asphalt binder after aging. The SBS-modified rejuvenating agent was the most favorable among the four types of rejuvenators, where a rejuvenator dosage of 12% showed the optimal rejuvenation effect. The addition of regenerators could appropriately improve the elastic deformation capacity of the aged asphalt binder. The epoxy soybean oil in the regenerant reacted with the aging SBS-modified asphalt binder, supplementing the lost oil in the aged SBS-modified asphalt binder, dispersing the excessive accumulation of asphaltene, and making the residual SBS swell again. The viscoelastic properties of the aging asphalt binder were improved by adjusting the content of components and functional groups to achieve the purpose of regeneration. Full article

When exposed to sun radiation and heat, asphalt binders age, resulting in reduced flexibility, cracking, and pavement failure. Given the increasing demands of traffic, environmental concerns, and resource scarcity, highway agencies and researchers are actively seeking solutions that meet performance requirements and demonstrate awareness of using non-renewable resources. Epoxy asphalt (EA) promotes sustainability concepts due to its production at significantly lower mixing and compaction temperatures, enhanced durability, improved serviceability, reduced maintenance needs, and successful recycling and reuse in hot asphalt mixtures. Crumb rubber, a widely recognized recycled waste tire material, is considered a viable option for promoting sustainability and enhancing asphalt binder properties. This study aims to enhance the durability and long-term performance of asphalt binders by utilizing sustainable materials. Six types of asphalt binders were employed: PG 67-22 base asphalt binder; styrene–butadiene–styrene (SBS)-modified PG 76-22 and PG 88-22H (3.5% and 7.0% dosage rates, respectively); a hybrid PG 76-22CS-modified asphalt binder prepared with SBS and crumb rubber modifiers; and 25EAB and 50EAB epoxy-modified asphalt binders prepared at 25 and 50% dosage rates, respectively. Results indicate that the sustainable asphalt binders PG 76-22CS, 25EAB, and 50EAB demonstrated comparable or superior performance compared to SBS-modified asphalt binders, as measured by rutting and fatigue factors. Additionally, epoxy asphalt binders had better anti-aging and cracking resistance, as shown by the outcomes of Fourier-transform infrared spectroscopy and linear amplitude sweep tests, respectively. This study contributes valuable insights into the potential of sustainable materials to enhance the overall performance and resilience of asphalt binders. Full article

Epoxy-modified asphalt binder has been widely used in steel deck pavement due to its excellent properties and it is a potential candidate for long life pavements. However, its short reserve time limits its widespread application in pavement engineering. Therefore, this work developed a novel epoxy-modified asphalt binder composed of a laboratory-made curing agent as a solution. Firstly, optimization of preparation temperature of this new material was studied to balance the requirements of enough construction time and the material strength and elongation. The epoxy-modified asphalt binder, prepared at the optimal temperature of 140 °C, had a reserve time exceeding 120 min, whereas the tensile strength and the elongation at failure were 2.22 MPa and 216%, respectively, which satisfied the standard requirements of paving epoxy material well. Secondly, the asphalt mixture property tests demonstrate excellent high-temperature rutting resistance, water stability and low-temperature anti-cracking ability. Additionally, the compatibility and colloidal stability of this epoxy-modified asphalt binder were analyzed in terms of microphase structure. The uniform microphase distribution of this binder showed by the laser confocal microscope observation in both short-term aging case and long-term aging case, indicates the great compatibility between asphalt and epoxy resin during paving process and service life. Furthermore, fatigue tests were conducted to evaluate the long-term durability. The fatigue life of epoxy-modified asphalt mixtures increased by 435%, 427%, 342%, and 276% under the stress ratios of 0.3, 0.4, 0.5, and 0.6, respectively, compared to those of SBS-modified asphalt mixtures. All these results indicate that the new epoxy-modified asphalt material is promising for applications in pavement engineering, especially suitable for long-life road pavement. Full article

A key factor in ensuring the stability and ductility of asphalt pavements is interlayer fatigue resistance. Interlayer bonding characteristics are one of the most significant elements influencing the lifespan of asphalt pavements. Poor bonding properties often lead to debonding, slippage cracking, and pavement deformation. The primary cause of interlayer slippage cracking is a lack of interface bonding between an asphalt overlay and underlayer, which is typically triggered by vehicle braking and turning. Emulsified asphalt, modified asphalt, and hot asphalt are just a few of the materials that are used as tack coats to address this issue. This paper examines five different bonding types between interlayers: a model with no tack coat, a model with SBS-modified hot asphalt, a model with SBS-modified asphalt emulsion, a model with an epoxy resin binder, and a model with SK-90 hot asphalt. This study evaluates the shear fatigue of asphalt pavement under a single wheel cycle load. A model is created using the Abaqus software to predict fatigue life while taking into account the various tack coat materials listed above. Considering the outcomes of this study, the best bonding type for asphalt pavement is SBS-modified hot asphalt. After selecting this material, various tack coat thicknesses were used until the optimum thickness of 6 mm was determined. The proposed model can withstand more load cycles and less rutting depth, which helps to prevent interlayer fatigue failure over the course of a pavement’s design life. Full article

Asphalt pavement recycling technology with high reclaimed asphalt pavement (RAP) content has always been limited by unsatisfactory pavement performance and the rising cost of pavement materials. To address these challenges, polyurethane-prepolymer-modified bitumen (PPB) was proposed to be utilized as the asphalt binder of fully reclaimed asphalt pavement (FRAP) in this study. The proper formula of the PPB binder was determined based on a range of tests. The rheological behavior and tensile properties of the PPB binder were then investigated, and the economic cost of materials was discussed as well. Results revealed that the PPB system can be obtained through chemical synthesis using readily available raw materials. The reaction of polyurethane prepolymer and chain extender provides PPB with significant improvement in temperature susceptibility, rutting resistance, and tensile properties. It is also demonstrated in this study that the PPB mixture containing 100% RAP, on the whole, takes advantage of cost-saving especially compared to the epoxy asphalt mixture. Therefore, the PPB binder exhibits a favorable application prospect in FRAP. Full article

The quality of pavements in tropical climates is negatively affected by the frequent wet and dry cycles during the rainy season, as well as by issues related to overloading from heavy trucks and traffic congestion. Contributing to this deterioration are factors such as acid rainwater, heavy traffic oils, and municipal debris. In light of these challenges, this study aims to assess the viability of a polymer-modified asphalt concrete mixture. This study investigates the feasibility of a polymer-modified asphalt concrete mixture with the addition of 6% crumb rubber powder from waste car tires and 3% epoxy resin to counter the harsh conditions of tropical climate weather. The study involved subjecting test specimens to five to 10 cycles of contaminated water (100% rainwater + 10% used oil from trucks), curing for 12 h, and air drying in a chamber of 50 °C for 12 h to simulate critical curing conditions. The specimens underwent fundamental laboratory performance tests such as the indirect tensile strength test, dynamic modulus test, four points bending test, and Cantabro test, as well as the double load condition in the Hamburg wheel tracking test to determine the effectiveness of the proposed polymer-modified material in actual conditions. The test results confirmed that the simulated curing cycles had a critical impact on the durability of the specimens, with the greater curing cycles leading to a significant drop in the strength of the material. For example, the TSR ratio of the control mixture dropped from 90% to 83% and 76% after five and 10 curing cycles, respectively. Meanwhile, the modified mixture showed a decrease from 93% to 88% and 85% under the same conditions. The test results revealed that the effectiveness of the modified mixture outperformed the conventional condition in all tests, with a more prominent impact observed under overload conditions. Under double conditions in the Hamburg wheel tracking test and a curing condition of 10 cycles, the maximum deformation of the control mixture sharply increased from 6.91 to 22.7 mm, whereas the modified mixture increased from 5.21 to 12.4 mm. Overall, the test results confirm the durability of the polymer-modified asphalt concrete mixture under harsh tropical climate conditions, promoting its application for sustainable pavements, especially in Southeast Asian countries. 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

Conventional asphalt concrete pavements have deteriorated rapidly due to the current increased traffic and extreme climate impacts. In addition to the upgrading in the construction quality, there is an urgent need to expand the utilization of modified asphalt binders to improve road capacity and traffic safety. The proposed research aims to combine epoxy resin (ER) and crumb rubber powder (CRP) contents into conventional Styrene-butadiene-styrene (SBS)-modified asphalt binder to not only reduce the consumption of normal asphalt binder but also promote the usage of recycled waste material in practice. To cope with this research objective, the ER and CRP were designed at 3% and 5% by weight of asphalt binder, respectively. Various laboratory tests were performed to evaluate the performance of modified mixtures (ERCRP), including the Frequency Sweep Test, Multiple Stressed Creep and Recovery, Dynamic Modulus, Semi-Circular Bending (SCB), and Cantabro Durability Tests. Additionally, an assessment of the modified asphalt concrete pavement via field testbed was conducted through Falling Weight Deflectometer and Ground Penetrating Radar. Overall, by adding the ER and CRP, the strain value of the control reference mix can be reduced up to 31.8% and 28.3% at MSCR 0.1 and 3.1 kPa, respectively. Additionally, the dynamic modulus of the ERCRP-modified samples was approximately 32,267 and 189 MPa, while the value of the reference mixture was 28,730 and 105 MPa at the highest and lowest frequency, respectively, indicating an enhancement under repeated loads. Regarding the SCB test results at 0 °C, the peak stress of the ERCRP-modified mixture was 4.75 MPa, while the value of the reference specimens was only 4.2 MPa, noticing the improved stress-bearing capacity. Based on a full-scale testbed, the FLWD elastic modulus of reinforced pavement shows a novel improvement (6.75%) compared with the control pavement, suggesting a potential application of ERCRP-modified asphalt binder for sustainable development purposes. Full article

This study examines the mechanical performance, deformability properties and rheological properties of a newly developed waterborne epoxy resin (WER)-modified emulsified asphalt (WE/A) binder for micro-surfacing. Two types of WER, semi-flexible and rigid, were used to modify the binder. Furthermore, the modification mechanism was investigated using the fluorescent microscope test and the scanning electron microscope (SEM). In addition, the pavement performance at micro-surfacing was studied using the wet wheel wear resistance test, the pendulum friction test and the slurry rutting test. The results indicated that with a small content (<15%) of WER in WE/A, WER existed as a continuous structure (cellular membrane wrapped around asphalt bubbles), thereby enhancing its high temperature properties and mechanical properties. Meanwhile, it also improved the cohesion properties of the transition interface between the aggregate and asphalt (enhanced by at least 30.0%) and the rutting resistance (improved by about 55.3–63.8%). In addition, WER could also improve the peeling resistance and water damage resistance of the micro-surfacing. Full article