Creep Recovery Research Articles

Recycling the electric arc furnace waste after geopolymerization in bitumen: experimental analyses and LCA study

The conversion of solid waste materials into cleaner products for road paving. applications appears to be a promising and sustainable option. However, there is still a lack of attention given to quantifying the potential environmental benefits of recycling solid wastes in asphalt pavements, regarding the impact on asphalt performance. To address this gap, the present study investigates the effects of recycling electric arc waste based geopolymers on asphalt binder and mixture characteristics, as well as environmental outputs. For this purpose, geopolymers were incorporated into both neat and SBS-modified binders. A comprehensive rheological investigation was conducted using cutting-edge multiple stress creep recovery (MSCR) and linear amplitude sweep (LAS) analyses. Stability, Marshall quotient, and flow values, as well as dry and wetconditioned tensile strength were considered, to determine asphalt mixture properties. In the Life Cycle Assessment (LCA), greenhouse gases resulting from fuel and energy consumption in each inventory phase were determined. The varying service lifetimes, maintenance and rehabilitation plans, and production and construction requirements of the different asphalt schemes were taken into account. Subsequently, the environmental impacts of the asphalt mixtures, including global warming potential, acidification, eutrophication, and smog formation potential, along with the total energy demand, were calculated across different stages of the LCA. The results show that the geopolymerization process results in important contributions in terms of both environmental savings and pavement performance.

Application of fume silica nanoparticles to improve high-temperature rheological performance of terminal blend rubberized asphalt

This study aims to evaluate the impact of fume silica nanoparticles (FSNPs) on the high-temperature rheological properties of terminal blend rubberized asphalt (TBRA). In this study, FSNPs were utilized to modify TBRA asphalt with three different CR contents (30%, 40%, 50%). The micro-morphology of FSNPs was observed through Scanning Electron Microscopy (SEM) experiments. The effects of FSNPs on the high-temperature rheological properties of TBRA were assessed using temperature sweep tests, Multiple Stress Creep Recovery (MSCR), and rotational viscosity tests. Furthermore, the influence of FSNPs on the chemical and thermal properties of TBRA was analyzed through Fourier Transform Infrared Spectroscopy (FTIR) and Thermogravimetric Analysis (TGA) tests. Rheological tests and SEM results indicate that FSNPs can effectively enhance the high-temperature elasticity, fatigue resistance, and deformation resistance of TBRA binders. This improvement is attributed to the unique branched network structure of FSNPs, which plays a pivotal role in enhancing the elasticity within the TBRA asphalt matrix. Additionally, the degradation of TBRA's low-temperature performance due to FSNPs is minimal. Considering the optimal viscosity for FSPN-modified TBRA, recommended ratios are: TB30/6%, TB40/4%, and TB50/2%. FTIR and TGA results demonstrate that the modification of TBRA by FSNPs is primarily physical blending, and the addition of FSNPs enhances the thermal stability of TBRA.

Study on the influencing factors of mechanical properties of anti-icing modified asphalt mortar

Accumulated snow and ice on road surface affect traffic operation. Anti-icing asphalt pavement is widely implemented as an active snow melting technology. However, there are few studies on anti-icing modified asphalt mortar mechanical properties and the effect of mortar materials on the interaction between modified asphalt and anti-icing filler. For this reason, this study investigated the mechanical properties of asphalt including rheological, high-temperature, fatigue and low-temperature properties through frequency and temperature scan, multiple stress creep recovery, linear amplitude scan, and single edge notched beam test. Based on this, the significant factors affecting asphalt mechanical properties were identified by analysis of variance. Subsequently, the Palierne-C-G* parameter was used to quantify the interaction between modified asphalt and anti-icing filler, and the effect of asphalt chemical structure on the interaction was revealed by Fourier Transform Infrared Spectroscopy (FTIR) test. The results indicated that the anti-icing filler significantly improved the high temperature and fatigue resistance of asphalt. Compared with SBS modified asphalt mortar, the mechanical properties of composite modified asphalt mortar were superior. The most significant factor affecting the mechanical properties of SBS modified asphalt mortar was modifier dosage, while the most significant factor affecting the composite modified asphalt mortar was crushed rubber dosage. The interaction showed a decreasing trend with the increase of frequency, while it appeared to increase and then decrease with the increase of temperature. The carbonyl functional group of asphalt correlated best with the interaction between asphalt and filler.

Evolution of aging depth gradient distribution in SBS-modified bitumen during the aging of field

This study investigated the distribution of aging depth gradients in styrene-butadiene-styrene modified bitumen (SBSMB) during natural aging. SBSMB was sourced from bitumen recycling tests and was stratified into upper, middle, and lower layers according to depth. To examine the effects of various aging depths, SBSMB samples from different depths were prepared for subsequent bitumen recycling tests. Then, studying the rheological performance of the SBSMB involved conducting multiple stress creep recovery tests. Subsequently, investigating the bee structure and nanoscale indicators of SBSMB at various aging depths involved utilizing atomic force microscopy testing. Finally, the Verhulst model was applied to assess the aging of SBSMB at different depths. The results have shown that natural aging has gradually diffused from the surface to the interior of the bitumen. An increase in aging time leads to a more pronounced aging effect at the upper levels and an accelerated the downward diffusion rate. This ultimately results in a gradient behavior of the rheological properties of SBSMB at different depths. The quantity of bee structures and the distribution density of bee structures in SBSMB both progressively decrease with increased aging depth. As aging time increases, the aging properties of SBSMB exhibit significant gradient behavior at different depths. Simultaneously, the Verhulst model accurately explain the aging trend of bitumen at different nanoscale depths.

Improvement of physicochemical properties and quercetin delivery ability of fermentation-induced soy protein isolate emulsion gel processed by ultrasound

This study aimed to investigate the effects of ultrasonic treatment at different powers on the physicochemical properties, microstructure and quercetin delivery capacity of fermentation-induced soy protein isolate emulsion gel (FSEG). The FSEG was prepared by subjecting soy protein isolate (SPI) emulsion to ultrasonic treatment at various powers (0, 100, 200, 300, and 400 W), followed by lactic acid bacteria fermentation. Compared with the control group (0 W), the FSEG treated with ultrasound had higher hardness, water holding capacity (WHC) and rheological parameters. Particularly, at an ultrasonic power of 300 W, the FSEG had the highest hardness (101.69 ± 4.67 g) and WHC (75.20 ± 1.07%) (p < 0.05). Analysis of frequency sweep and strain scanning revealed that the storage modulus (G') and yield strains of FSEG increased after 300 W ultrasonic treatment. Additionally, the recovery rate after creep recovery test significantly increased from 18.70 ± 0.49% (0 W) to 58.05 ± 0.54% (300 W) (p < 0.05). Ultrasound treatment also resulted in an increased β-sheet content and the formation of a more compact micro-network structure. This led to a more uniform distribution of oil droplets and reduced mobility of water within the gel. Moreover, ultrasonic treatment significantly enhanced the encapsulation efficiency of quercetin in FSEG from 81.25 ± 0.62 % (0 W) to 90.04 ± 1.54% (300 W). The bioaccessibility of quercetin also increased significantly from 28.90 ± 0.40% (0 W) to 42.58 ± 1.60% (300 W) (p < 0.05). This study enriches the induction method of soy protein emulsion gels and provides some references for the preparation of fermented emulsion gels loaded with active substances.

Rheological and microstructural properties of nano-composite bitumen modified by nano-alumina and low-SBS content

This study explores a new nanocomposite-modified bitumen (NCMB) that could be more cost-effective and environmentally friendly than current options. It achieves this by combining a lower amount of styrene butadiene styrene (SBS) polymer with nano-alumina, aiming to improve performance at high and moderate temperatures. This innovative material aims to overcome the performance limitations of traditional polymer-modified bitumen (PMB). Moreover, this NCMB, which uses less modifier (SBS) and nano-alumina, paves the way for more economical and eco-friendly roads, leading to significant fuel savings. The new NCMB was prepared by mixing various nano-alumina contents (2, 3, 4, and 5 % by weight of bitumen) with low-SBS content (2.5 % by weight of bitumen) PMB. Multiple stress creep recovery (MSCR) and linear amplitude sweep (LAS) tests, further the Superpave standard method, were used to assess the rutting and fatigue cracking resistance of PMB and NCMBs. Field emission scanning electron microscopy (FESEM) with elemental analysis by energy dispersive X-ray spectroscopy map (EDS) techniques and Fourier-transform infrared spectroscopy (FTIR) was used to investigate the microstructural and elemental characteristics of NCBBs. The results demonstrated that adding nano-alumina to low-SBS content PMB significantly enhanced both the storage stability and its durability over time (i.e. aging resistance) of the NCMBs. The MSCR test results showed that samples with 5 % nano-alumina had a rutting resistance higher than the PMB, up to 31 %. The NCMB samples with 4 % nano-alumina demonstrated a significant improvement in fatigue resistance of up to 67 %. The FTIR results revealed a 64 % improvement in aging resistance for NCMBs containing 3 % nano-alumina compared to the PMB. The storage stability values increased for all NCMB types and reached 62 % for the samples with 5 % nano-alumina. Overall, adding nano-alumina to low-SBS content PMB led to a remarkable improvement of rheological properties at intermediate and high temperatures and a stable system under storage conditions with high anti-aging resistance.

Evaluation of asphalt binder and mixture properties utilizing fish scale powder as a biomodifier

Fish represents an abundant and underutilized waste product from the fishing industry. This study investigated the effects of incorporating fish scale powder (FSP) at various dosages (3%, 6%, 9%, and 12%) on the properties of asphalt binder and mixtures. Conventional tests, viscosity, storage stability, Fourier transform infrared spectroscopy, and multiple stress creep recovery tests were conducted on the binder. Mix design, wheel tracking, indirect tensile strength, fatigue, and ultrasonic pulse velocity tests were evaluated for the asphalt mixtures. The results showed that FSP increased the binder’s stiffness and reduced the temperature susceptibility but compromised the low-temperature performance and workability regardless of the dosages. The storage stability test results demonstrated the improved high-temperature storage stability. In the mixtures, the permanent deformation resistance enhanced with increasing the FSP content, decreasing the rut depth from 4.3 mm for the control sample to 2.9 mm at 12% FSP. The moisture damage resistance, indicated by the tensile strength ratio, increased from 90% for the control sample to 94.1% at 12% FSP. However, the fatigue life decreased from 14010 cycles for the control sample to 11190 cycles at 12% FSP. The dynamic and elastic modulus values before conditioning increased with higher FSP dosages, and this increasing trend was also observed after conditioning, signifying greater stiffness retention and moisture resistance of the asphalt mixtures containing higher amounts of FSP. Numerically, the 6–9% FSP range offered the optimum balance, improving the rutting resistance by 18% and the moisture resistance by 3.2% compared to those of the control sample, while limiting the fatigue life to 12% and maintaining the workability. Overall, FSP has potential for use as an asphalt biomodifier by transforming an environmental liability into a value-added sustainable paving material.

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.

Prediction models for creep and creep recovery of fly ash concrete

In order to clarify the deformation effect of fly ash concrete members after loading and unloading subsequently, experiments on creep and creep recovery of fly ash concrete were carried out on consideration of three fly ash contents and two concrete loading ages. After comparing the available prediction models for concrete creep, the B4 model was modified by multiplying the influence coefficient and creep terms, and the fly ash concrete creep prediction model was established correspondingly. The comparison shows that the modified B4 model is in good agreement with the experimental data. Furthermore, based on the experimental phenomena and the development law of creep recovery of fly ash concrete, the prediction model for creep recovery of fly ash concrete was proposed in combination with the factors affecting creep recovery which include loading age, fly ash content, etc. Finally, the calculated values of the proposed creep recovery model were compared with the experimental results and the applicability of the model was discussed. The creep and creep recovery model of fly ash concrete proposed is of great significance for revealing the time-varying law of fly ash concrete and improving the performance of concrete structures.

Study of High-Temperature Rheological Properties of Emulsified Asphalt Residues

The residue of emulsified asphalt is its final state when it becomes part of an asphalt mixture. Therefore, the mechanical properties of the residue have a significant impact on the performance of emulsified asphalt mixtures. Dynamic shear rheological tests and fluorescence microscopy were conducted to explore the effects of emulsification and aging on the rheological properties and micro-morphology of emulsified asphalt residue. The results of both the temperature sweep and multiple stress creep recovery tests indicated that the emulsification of the asphalt had different effects on the rheological properties of the base asphalt and the styrene-butadiene-styrene (SBS)-modified asphalt. For the base asphalt, emulsification increases the complex shear modulus by about 5% and reduces irrecoverable creep flexibility by 30%. However, the physical grinding effect of the colloid mill during the emulsification process could destroy the internal spatial network structure of SBS, leading to a reduction in the complex shear modulus by about 5% and a 10% increase in irrecoverable creep flexibility. This phenomenon is similar to the aging of SBS-modified asphalt, which, in turn, leads to a decline in the performance of emulsified SBS-modified asphalt residues.

Effect of UV radiation on the high temperature and fatigue performance of SBS modified asphalt and asphalt mixture

In this study, the effects of UV radiation on the high temperature fatigue performance of SBS modified asphalt and asphalt mixtures were analyzed, and the effects of outdoor atmospheric UV radiation were simulated by indoor UV accelerated aging test. The results showed that the increase of UV radiation time led to the increase of creep recovery rate of asphalt and the decrease of irrecoverable creep flexibility, i.e., the resistance to permanent high temperature deformation of SBS modified asphalt was improved. The fatigue cracking resistance of asphalt was weakened and accelerated by radiation. UV radiation increased the rutting resistance of asphalt mixtures and weakened the fatigue resistance at high temperatures. At the same time, UV radiation reduced the aromatic and saturated content of SBS modified asphalt, which led to a reduction in the relative aromatic and saturated content of asphalt mixtures.

Multiple Stress Creep Recovery of High-Polymer Modified Binders: Consideration of Temperature and Stress Sensitivity for Quality Assurance/Quality Control Policy Development

High polymer-modified binders (HiPMBs) have recently been introduced in the Gulf region, where pavement structures are commonly subjected to severe climate conditions and heavy traffic loads because there is no enforcement of weight limits. Local agencies are currently modifying quality assurance/quality control (QA/QC) policies to accommodate such technology. In this study, HiPMBs produced by different refineries were subjected to physicochemical and thermal characterizations to investigate the compositional variability of industrial HiPMBs. Their thermal and stress susceptivity was then assessed through multiple stress creep recovery (MSCR) tests. The validation of the MSCR-based hierarchy was performed by assessing nine hot mix asphalts (HMAs) through repeated load permanent deformation tests and performing mechanistic-based structural analysis. Results showed that styrene-butadiene-styrene (SBS) is not the only modifier added to the bitumen, as commonly done in laboratory settings. These undisclosed modifiers disrupt the correlation between MSCR results and SBS concentration typically observed in laboratory-prepared HiPMBs, highlighting the importance of investigating plant-produced binders. Moreover, higher temperatures and stress levels returned different MSCR performance hierarchies among binders, questioning the effectiveness of the current MSCR test protocol for HiPMBs. Additionally, findings confirmed that the current MSCR testing protocol does not correctly assess the bitumen response in HMAs. A higher MSCR stress level shall be prescribed in the local QA/QC specifications to ensure the correct selection of HiPMBs in the region. This study can be used as a framework for other countries actively engaged in the implementation of HiPMBs and novel bituminous materials.

Investigation of rheological properties of asphalt modified with low-temperature microencapsulated eutectic phase change materials

The effects of microencapsulated eutectic phase change materials (MEPCMs) on the viscosity-temperature relationship, viscoelasticity, creep recovery, and low-temperature properties of base asphalt and SBS asphalt were investigated using dynamic shear rheometer (DSR) and bending beam rheometer (BBR). The results revealed that the incorporation of microcapsules led to a reduction in the complex modulus and viscosity of the asphalt. Notably, at a concentration of 13 wt%, microcapsules disrupted the linear viscoelastic behavior of the asphalt and compromised its phase uniformity. However, the addition of microcapsules improved the low-temperature rheological properties of the asphalt. Specifically, the S and m-values of the asphalt decreased and increased, respectively, with increasing microcapsule content. Moreover, SBS asphalt exhibited less susceptibility to the effects of microcapsules compared to base asphalt, owing to its superior performance across a wide range of temperatures. This characteristic renders SBS asphalt more compatible with MPCMs for practical applications.

Evaluation of the effect of different preparation processes on the road performance of thermoplastic resin modified porous asphalt mixtures

In order to evaluate the effects of three preparation processes, namely dry process (DP), wet process (WP) and wet/dry mixing process (MP), and resin high viscosity modifier (RHVM) on the road performance of porous asphalt mixtures, the frequency scanning, multi-stress creep recovery, and bending beam rheometer tests were used to analyze the rheological performance of resin-modified high viscosity asphalt under different processes. Uniaxial compression, Wheel tracking, Semi-circular bending and Freeze-thaw indirect tensile tests were used to test the properties of resin-modified porous asphalt mixtures under different processes. The commonly used TAFPACK-Super (TPS) modifier was a control group. Finally, the changes in the microscopic morphology characteristics and chemical composition were used to illustrate the enhancement mechanism of resin modifiers. The results showed that the high-temperature deformation resistance and low-temperature cracking resistance of RHVM modified asphalt prepared by DP and MP are weaker than that of the WP. Compared to the RHVM(WP), the Jnr(3.2) of RHVM(DP) and RHVM(WP) decreased by 14.3% and 63.8%, the strength modulus of RHVM(DP) and RHVM(MP) increased by 21.5%, 28.0% and the creep rate decreased by 2.37%, 4.45%, respectively. As for the performance of asphalt mixture, compared to the RHVM(WP) asphalt mixture, the dynamic stability of RHVM asphalt mixture prepared by the DP and MP decreased by 17.3–18.2%, σs and εs of RHVM(DP) and RHVM(MP) increased by 15–35% and 21–29%, respectively. The water stability of RHVM(DP) asphalt mixtures was better than that of RHVM(WP) when the mixing time reached 180 s. RHVM(WP) asphalt mixtures have superior low-temperature cracking resistance, comparable water stability, and slightly poorer high-temperature stability than that of TPS(WP) asphalt mixture. Microscopic morphology observation found that some modifier particles and asphalt binder did not realize effective mixing under the DP and MP, and infrared spectroscopy results confirmed that TPS modifiers are mainly physically co-mingled with asphalt, while the tackifier resin in the RHVM reacts with the asphalt to form new functional groups to increase the viscosity of the asphalt.

Effect of PCL chain length on rheological and mechanical properties of PCL‐PDMS‐PCL triblock copolymer films

AbstractThe polycaprolactone‐polydimethylsiloxane‐polycaprolactone (PCL‐PDMS‐PCL) triblock copolymer films of variable PCL chain are analyzed for rheological characteristics in this paper. The dynamics of viscoelastic behavior of photocrosslinked films above their crystal melting temperature (Tcm) is measured using oscillatory shear rheology experiments. The frequency sweep tests are analyzed at 0.1% strain as obtained from linear viscoelastic region. Shear thinning is observed in the study of complex viscosity. It has been noted that viscosity rises with increase in crosslink density and decrease in with PCL chain length. Time‐dependent effect on the copolymer films has been analyzed by creep recovery behavior. The Burgers model is fitted in creep compliance data to analyze its viscoelastic and viscous region. An examination of structure recovery revealed that recovery increased as PCL chain length decreased. Tensile strength and percentage elongation are studied at ambient conditions with a universal testing machine, while storage modulus and tan δ are analyzed by a dynamic mechanical analyzer at varying temperatures.

Incorporation of intermediate wheatgrass (Thinopyrum intermedium) into bread wheat doughs: Effects on pasting and rheological properties

AbstractBackground and ObjectivesIntermediate wheatgrass (IWG), a resilient perennial grain with adaptability to difficult climates, is emerging as a compelling candidate for sustainable food solutions in bakery product applications. This study evaluated the pasting and rheological properties of doughs made from bread wheat flour and blended bread wheat–IWG flours (IWG content: 15%, 30%, 45% and 60%), with the goal of exploring the potential of IWG flour as a nutritious and sustainable ingredient in cereal‐based products.FindingsThe RVA peak, trough, and final viscosity values significantly (p &lt; .05) decreased, and the pasting temperature increased as the IWG substitution level increased. IWG‐containing flour blends had a lower retrogradation tendency compared to the control. As the IWG flour substitution level increased, both empirical (Mixograph, Kieffer dough and gluten extensibility, Glutograph) and fundamental (linear oscillatory frequency sweep and creep–recovery) rheological measurements indicated relatively weaker dough properties imparted by the addition of the IWG flour.ConclusionsThe outcomes of this research will shed light on the impacts of utilizing alternative grains, such as intermediate wheatgrass, in bakery applications. This will provide insights that could inform the development of nutritious and sustainable baked products to meet the demands of health‐conscious consumers.Significance and NoveltyThe dough weakening effect of the IWG flour was tolerated at the 15% IWG flour substitution level. At lower substitution levels, the IWG‐containing flour blends exhibited a lower retrogradation tendency compared to bread wheat flour, which could indicate lower staling of loaves of bread during bread storage without compromising the physical quality of bakery products. Finally, the present research fills a critical gap in the literature as it represents the first application of fundamental rheological methods at known and controlled strain and stresses to evaluate the physical properties of doughs prepared from IWG flour blends.

Thermal Oxidative Aging Effect on Chemo-Rheological and Morphological Evolution of Crumb Rubber Modified Asphalt Binders with Wax-Based Warm Mix Additives

Wax-based warm mix additives can decrease the viscosity and improve the workability of crumb rubber (CR)-modified asphalt, but the mechanism of influence on the aging performance of CR-modified asphalt is not clear. To investigate the thermal aging behavior and mechanism of wax-based warm mix CR-modified asphalt, polyethylene wax (PEW) and polyamide wax (PAW) were mixed to prepare warm mix CR-modified asphalt. The effect of thermal aging on the rheological and mechanical properties was characterized by a basic property test, frequency sweep test, and multiple stress creep recovery test. The chemical composition changes during aging were then analyzed by Fourier transform infrared spectroscopy and gel permeation chromatography. Finally, the phase morphology during thermal aging was observed by fluorescence microscopy. The results showed that compared with the degradation of CR, the oxidative aging of the asphalt binder played a dominant role in the process. Not only did PEW and PAW attach to the asphalt surface in the form of crystallization to prevent its reaction with oxygen but they also promoted the dissolution of CR, and released polymerization chains, thereby enhancing the antiaging properties of CR-modified asphalt. Furthermore, the antiaging of PAW/CR-modified asphalt was better than that of PEW/CR-modified asphalt, because the amide group of PAW reacted with CR-modified asphalt to form a polymer structure.

Rheology of Crumb Rubber-Modified Warm Mix Asphalt (WMA).

This study explores the impact of adding waste vehicular crumb rubber to the commercially available warm mix additives Sasobit® and Zycotherm® on modified asphalt binders' physical and rheological properties. Various concentrations of crumb rubber (0%, 10%, 15%, and 20%) were introduced to asphalt binder samples with 2% and 4% Sasobit and 1.5% and 3% Zycotherm. The investigation employed conventional tests (penetration and softening point) and advanced mechanical characterization tests, including Superpave rotational viscosity (RV), Dynamic Shear Rheometer (DSR), DSR multi-stress creep recovery (MSCR), DSR linear amplitude sweep (LAS), and Bending Beam Rheometer (BBR). Traditional tests measured the asphalt consistency, while workability was assessed through the RV test. The results showed that the Zycotherm binders experienced a more significant penetration reduction than the Sasobit binders. Additionally, an increased crumb rubber content consistently elevated the softening point and rotational viscosity, enhancing the complex shear modulus (G*) values. Rubberized binders exhibited an improved rutting performance and low-temperature PG grades. Increasing the crumb rubber content enhanced fatigue life, with Z1.5CR20 and S2CR20 demonstrating the longest fatigue lives among the Zycotherm and Sasobit binders, respectively. Overall, Z1.5CR20 is recommended for colder climates, while S2CR20 is suitable for hot-climate applications based on extensive analysis.

Rheological Performance Analysis of Different Preventive Maintenance Materials in Porous High-Viscosity Asphalt Pavements.

Porous asphalt pavements are widely used in rainy and wet areas for their skid resistance, noise reduction, runoff minimization and environmental sustainability. Long-term moisture vapor erosion and the destabilization of large pore structures can easily result in pavement problems such as fragmentation, spalling, cracking, and excessive permanent deformation. To this end, four different preventive maintenance materials, including the rejuvenation (RJ), cohesion reinforcement (CEM), polymerization reaction, and emulsified asphalt (EA) types, were selected in this paper to improve the high-viscosity porous asphalt pavement. The effects of the different preventive maintenance materials on the temperature sensitivity, rheological properties and fatigue performance of high-viscosity modified asphalt were evaluated through temperature sweep, frequency sweep, multi-stress creep recovery (MSCR), linear amplitude sweep (LAS), and bending beam rheometer (BBR) tests. The results showed that the four preventive maintenance materials exhibit different enhancement mechanisms and effects. RJ improves the fatigue properties, deformation resistance and low-temperature cracking resistance of aged asphalt by adding elastomeric components; CEM materials are more conducive to increasing the low-temperature crack resistance of aged asphalt; while GL1 and EA improve the viscoelastic behavior of aged asphalt, but the effect of the dosing ratio needs to be considered.

Evaluation of the laboratory aging of field-blended crumb rubber modified binder

Field-blending approach is widely employed by the industry to introduce crumb rubber into asphalt binder. Rubber-modified binder provides satisfactory performance and benefits the environment by consuming recycled rubber manufactured from scrap tires. This work investigated the aging mechanism and post-aging performance of rubber-modified binders using laboratory aging protocols. Four rubber-modified binders containing two rubber contents (5 and 10 percent) and two particle sizes (passing 1.18 mm and 2.36 mm, respectively) were evaluated in this study. After multiple laboratory aging protocols, chemical components in aged binders were measured with Fourier transform infrared spectroscopy. Chemical analysis revealed that rubber-modified binders accumulated fewer oxidative aging products (carbonyl and sulfoxide components) than their unmodified base binder after long-term aging. Increasing rubber content and particle size increased the complex shear modulus while decreasing the phase angle of the binder. Binder viscosities were back-calculated from complex moduli and phase angles. A linear correlation between logarithmic viscosity and carbonyl area index exists for the long-term aged rubber-modified binders. This linearity can be used to predict the age-hardening of rubber-modified binders. These binders were also tested in dynamic shear rheometer to determine performance grades. Multiple stress creep recovery tests evaluated the rutting resistance of short-term aged binders. Bending beam rheometer was used to evaluate the low-temperature cracking resistance of long-term aged binders. These test results showed that rubber-modified binders provided better rutting and cracking resistance than their base binder. Statistical analysis indicated that carbonyl components correlated to the binder performance at various aging statuses.