Dynamic Shear Rheology Research Articles

REOB/SBS Composite-Modified Bitumen Preparation and Modification Mechanism Analysis

To investigate the effect of recycled engine oil bottoms (REOB) as a compatibilizer on the properties of styrene–butadiene–styrene-modified bitumen (SBS-PMB), this paper studied the preparation method, properties, and micro-mechanism of composite modification of matrix bitumen with SBS and REOB. Firstly, a multi-factor orthogonal experiment determined the optimal preparation scheme of REOB/SBS composite-modified bitumen (REOB/SBS-PMB). Then, the high-temperature stability rheological properties, and anti-aging performance of REOB-PMB were studied by testing Brookfield viscosity, elasticity recovery, and dynamic shear rheology (DSR) and by short-term aging simulation (TFOT). Finally, the microstructure, fraction content, and SBS particle dispersion of 70# matrix bitumen (70-MB), SBS-PMB, and REOB/SBS-PMB were compared and analyzed by tests of Fourier transform infrared spectroscopy (FTIR), rod-shaped thin-layer chromatography, and fluorescence microscopy to reveal the micro-mechanism of REOB improving SBS and bitumen compatibility. The research results showed that the mixing form of SBS and REOB in bitumen was mainly physical swelling and blending, with chemical changes also present that have a minor impact. The light fraction in REOB increased the flowability of bitumen, promoted the swelling of SBS, improved the compatibility between SBS and bitumen, and improved the high-temperature stability and rheological properties while reducing the impact of aging.

Performance Evaluation of Reinforced Asphalt Using Six Organic and Inorganic Fibers

This paper aims to evaluate the performance of asphalt individually reinforced by six types of fibers, including three organic and three inorganic fibers, to study the interface between fibers and asphalt, and to analyze their relationships. Specifically, the chemical and physical interaction between fiber and asphalt was analyzed using FTIR testing. The interface pullout behavior of the fibers from asphalt was analyzed using a fiber-asphalt pullout (FAP) test. The high-temperature performance of the fiber-reinforced asphalt using dynamic shear rheology (DSR) testing. The relationship between the performance index and interface index was analyzed using linear and grey correlation methods. Meanwhile, the interface micromorphology was observed using SEM testing. The results showed that the inorganic fibers and organic fibers mainly physically interacted with the asphalt. The interface bonding ability between BF-A and asphalt was the largest, followed by BF-B, GF, PEF, PAF-A, and PAF-B. The organic fibers decreased the phase angle and increased the complex modulus and rutting factor better than the inorganic fibers. The performance index G* and G*/sinδ are positively correlated with the interface pullout parameters. The influence of the interface pullout parameters on the performance index G* was the biggest, followed by the fiber modulus, fiber volume content, and fiber density.

Chemical structure of rubber powder on the compatibility of rubber powder asphalt

The sedimentation problem of waste rubber powder in asphalt not only restricts the engineering application of rubber powder asphalt, but also impedes the recycling of waste rubber. To solve this industry malady, this study designs and prepares three different chemical structures of rubber powder, and systematically investigates the influence of the chemical structure of rubber powder on the compatibility of rubber powder asphalt by cigar tube test, dynamic shear rheology test, microscopic characterization analysis, and molecular dynamics method. The microstructure results indicate that new characteristic peaks (such assulfonic acid groups, thiol groups, and amino groups) appeared in the infrared spectra of each of the modified rubber powder. The elemental analysis further proves that the sulfur and hydrogen contents of the mechanochemical modified rubber powder (AR) have been reduced, the carbon and hydrogen contents of the sulfonated modified rubber powder (SR) have been reduced, and the nitrogen contents of the tetraethylenepentamine with mechanochemical co-modified rubber powder (NR) have been increased. These facts indicate that different chemically structured rubber powder have been successfully prepared. The macroscopic results show that NR and asphalt blends has a lower softening point difference (2.1 ℃) and segregation index (12%), followed by SR and AR, and waste rubber powder (WR) and asphalt blends is the highest in softening point difference (6.3 ℃) and segregation index (35%). Microscopic characterization results show that NR, SR, and AR can form a fuzzy phase interface with asphalt, and further quantitative analysis finds that NR has the highest compatibility index with asphalt (80%), followed by SR and AR, and WR has the lowest compatibility index with asphalt (36%). Molecular dynamics simulation indicates that the solubility parameter of NR and asphalt is the closest and its difference is the smallest (0.4 (J/cm3) 1/2) as well as the strongest intermolecular interactions (-563.93 kJ/mol), followed by SR, AR, and WR. All the above results reveal that the order of compatibility between four types of chemical structure rubber powder and asphalt is NR > SR > AR > WR. Furthermore, based on macroscopic, microscopic, and molecular dynamics simulation, the compatibility mechanism of different chemically structured rubber powder with asphalt could be that the acidic groups in SR and the thiol functional groups in AR can be dissolved with the acidic groups in asphalt based on the principle of similar solubility, which improves the compatibility of the rubber powder with asphalt. The NR contains strong polar alkaline groups, which can be combined with the acidic components of asphalt based on the principle of acid-base neutralization reaction, thereby improving the compatibility of the rubber powder with asphalt. In view of the above, it is not difficult to see that the combination of tetraethylenepentamine and mechanochemically co-modified rubber powder and asphalt has a promising application in the future construction of pavement engineering and recycling of waste tire resource.

Research on the road performance of self-adhesive basalt fiber geotextiles based on the background of long-life pavements

Achieving sustained asphalt pavements can minimize the structural damage brought on by minor pavement cracks, which will reduce the high repair and maintenance costs resulting from pavement distress. This study introduces a new composite geomaterial, self-adhesive basalt fiber geotextiles (SBFG) prepared by hot-melt lamination of basalt fiber cloth and modified asphalt, intended for the deterrence and control of reflection cracks in asphalt pavements. In this study, the self-adhesive geotextile was placed between the cement-stabilized macadam base and AC-20 surface layer to prepare composite samples, and the road performance was evaluated by a three-point bending test, Overlay Tester, dynamic shear rheology test, and the crack expansion time under different parameters of SBFG was simulated by ABAQUS finite element to predict the whole life cycle of the pavement structure. The results indicate that the fracture energy of the SBFG sample is the largest among all samples, and the structural design of fiber reinforcement disperses the concentrated stress at the crack tip, increases the stress area, and prolongs the time of crack expansion from the subgrade to the surface layer; Smooth and stable load loss curve of the sample in the reflection crack test, with slow crack expansion. This new geomaterial has an excellent rutting factor and maintains good resistance to permanent deformation at high temperatures; In the finite element prediction of fatigue cracking life of asphalt pavement, the structural life of the pavement with the addition of SBFG was improved by 78.3% compared to the control group. The application of basalt fibers in geosynthetics provides a new idea for achieving prolonged asphalt pavements.

Rheological properties of composite DTDM/DOP/SBS modified asphalt and its effect on high and low temperature performance

To investigate the effect of crosslinker (DTDM) and plasticizer (DOP) on the rheological properties of SBS modified asphalt at high and low temperatures. In this study, the composite DTDM/DOP/SBS modified asphalt was subjected to infrared spectroscopy, dynamic shear rheology, and low-temperature bending beam rheology experiments. Analysis of microscopic properties and high and low temperature rheological properties of composite DTDM/DOP/SBS modified asphalt. The findings of the tests suggest that the cross-linking agent (DTDM) and plasticizer (DOP) have a better chemical response with SBS modified asphalt. It may significantly increase SBS modified asphalt's high-temperature deformation resistance, elastic recovery capacity, low-temperature fracture resistance, and aging resistance. The research findings have theoretical and practical significance for enhancing asphalt high and low temperature performance.

The Effect of the Kaolinitic Clay and Asphaltenes on the Rheological Properties of Trinidad Lake Asphalt and Trinidad Petroleum Bitumen-Clay Composites

Trinidad Lake Asphalt (TLA) is a source of superior quality asphalt and is often specified as a mandatory ingredient for paving in high-demand applications. The TLA resource is limited and expensive and the ability to synthetically convert refinery petroleum bitumen such as Trinidad Petroleum Bitumen (TPB) into a TLA-like material would be a very profitable and more sustainable approach. The objective of this paper is to determine whether kaolinitic clay and asphaltenes when blended with TPB can improve its rheological properties and produce a TLA-like material. Studies were conducted using dynamic (oscillatory) shear rheology (DSR) to measure changes on the rheological properties of complex modulus, degree of stiffness, G*, and phase angle, degree of elasticity, δ, of blends. Although the addition of kaolinite to TPB resulted in changes to the rheological properties (G* and δ) of the blends to values closer in magnitude to TLA, the properties of TLA were not achieved. Removal of the inorganic kaolinitic component from TLA resulted in a significant decrease in the complex modulus and an increase in the phase angle to values close to TPB (δ equal to 89.6 for TLA and δ equal to 89.1), demonstrating the key role played by the kaolinitic clay in the rheological properties of TLA. The addition of Valencia clay and asphaltenes to TPB clearly showed that in tandem, they play a significant rheological role in the TPB blends as it was possible to produce blends with similar or even better rheological properties compared to pure TLA. The TPB blend containing 30% Valencia clay and 30% asphaltenes exhibited a G* higher than that of TLA and a δ that was marginally less than that of TLA. This study also demonstrated the ability to create customized TPB blends to suit special applications by manipulating the kaolinitic clay and asphaltenes content.

Development of rejuvenator using waste vegetable oil and its influence on pavement performance of asphalt binder under ultraviolet aging

With the development of road engineering, the shortage of resources and road damage are becoming increasingly serious. In this research, The regeneration effect of a rejuvenator on the ultraviolet (UV)-aged asphalt is tested. The rejuvenator is composed of base oil, plasticizer, toughener and petroleum resin. The recovery performance of aged asphalt inareas with strong UV light is compared using indoor asphalt aging tests. A representative UV aged asphalt is selected for experiments. The basic performance of regenerated asphalt with the mixed ratio of different materials is measured using penetration, softening point, and ductility tests. The orthogonal test design (OTD) and analytic hierarchy process (AHP) model are established, and the optimal match design of a rejuvenator is obtained. The performance of UV aged asphalt before and after regeneration is tested by dynamic shear rheology (DSR) and the Fourier Transform Infrared Spectroscopy (FTIR) test. The results show a strong link between the asphalt from the areas with intense UV light and the asphalt after indoor 50 h UV aging. Waste vegetable oil (WVO) is selected as the base oil for the rejuvenator. The proportion of plasticizer in the WVO was determined to 30% based on OTD-AHP model optimization, the toughening agent is 4%, and petroleum resin is 9%. The high-temperature performance of asphalt can be improved with a reasonable regenerative agent dosage. The FTIR test shows that the rejuvenator can dilute carbonyl and sulfoxide groups in aged asphalt, soften asphalt and restore asphalt pavement performance. The results of this study can be applied to the asphalt regeneration to provide road remediation measures for asphalt deterioration in high UV areas.

Thermoregulation, rheological properties and modification mechanism of asphalt modified with PUSSPCMs

Phase change materials (PCMs) can regulate asphalt temperature through thermal storage properties to prevent thermal damage in asphalt pavements. However, the effects of PCMs on the thermoregulation and rheological properties of asphalt require further study. In this study, polyurethane solid–solid phase change materials (PUSSPCMs) were prepared to impart thermoregulation properties to asphalt, and the effects of PUSSPCMs on the rheological properties and microscopic characterization of asphalt were investigated. The PUSSPCMs were produced by different soft segment mass fractions (70 %, 80 %, and 90 %), and they were used to prepare modified asphalt with varying contents (3 %, 5 %, and 7 %). Thermoregulation testing system, dynamic shear rheology (DSR), bending beam rheology (BBR) tests, differential scanning calorimetry (DSC), infrared spectroscopy (FTIR), scanning electron microscopy (SEM), and atomic force microscopy (AFM) were conducted to determine the thermoregulation, rheological properties, and modification mechanism of PUSSPCM-modified asphalt, respectively. The results show that the thermoregulation property of PUSSPCM-modified asphalt improves with the increase of soft segment mass fraction and content, 7 % P90 asphalt exhibits the best thermoregulation property with the excellent delayed time (1105 s) and temperature difference (7.1 ℃). The high-temperature rutting resistance of the modified asphalt is enhanced by decreasing the soft segment mass fraction and increasing the content of PUSSPCMs, with the 7 % P70 being the best asphalt type. The 7 % P90 asphalt exhibits the optimum low-temperature creep performance due to a higher soft segment mass fraction. The modified asphalt may be a physical modification since no new characteristic peaks appear. With the increase of soft segment mass fraction, the PUSSPCMs in asphalt transform from elastomer to a ribbon-like structure. Furthermore, the microscopic roughness (Sq) and Young's modulus of the modified asphalt decline with the increase in soft segment mass fraction and content of PUSSPCMs, implying an increase in microscopic crack resistance and a decrease in elasticity.

Understanding the microstructure of a functional meat analogue: Demystifying interactions between fungal hyphae and egg white protein

This study investigated the microstructure and interactions of heat treated concentrated Fusarium venenatum biomass, commonly referred to as ‘mycoprotein’ (MYC), as well as the impact of 3 wt % egg white protein (EWP) on those interactions – EWP being frequently added as a ‘binding agent’. Confocal laser scanning microscopy (CLSM) and cryo-scanning electron microscopy (Cryo-SEM) combined with energy dispersive spectroscopy analysis (EDS) demonstrated the filamentous nature of the MYC, made up of chitin and protein, with a filament aspect ratio typically between 130 and 140. Protein extraction and analysis via SDS-PAGE electrophoresis suggested that the most abundant native protein in the MYC had a molecular weight of 69.2 kDa, probably belonging to the heat shock 70 (HSP70) group. Frequency sweep dynamic shear rheology measurements were performed at combinations of 3 different values of pH (3, 5 and 7), NaCl concentration ([NaCl] = 0, 100 and 200 mM), CaCl2 concentration ([CaCl2] = 0, 50 and 100 mM) and wt. % MYC solids (5, 10, 15 and 20) without added EWP and with added EWP (MYC-EWP). For MYC the storage modulus G′ was seen to increase strongly with increasing wt. % MYC solids but also with [NaCl] and [CaCl2], the latter having greater impact at pH 5 and 7. The opposite trends were observed at pH 3, where G′ decreased with increasing concentration of ions, the highest G′ values for MYC occurring at pH 3 with no added salts. This suggests that electrostatic interactions between the MYC elements are key to the overall texture. On addition of EWP, there was good evidence that EWP completely coats the filaments so that, the hyphal interactions of MYC-EWP are then dominated by the response of EWP to changes in pH and salt composition. Gaining further understanding of the strength and distribution of the loci of these interactions is therefore key to better control of the texture of such meat analogues.

Study on the effect and mechanism of oyster shell powder on asphalt

ABSTRACT In order to explore the effect of oyster shell powder on asphalt. In this paper, oyster shell powder with a fineness of 40 mesh was added to the matrix asphalt in accordance with 3 %, 6 %, 9 %, 12 %, 15 %, and 18 % to prepare oyster shell powder modified asphalt. By establishing the molecular model of oyster shell powder modified asphalt with different contents, the influence of oyster shell powder on the mechanical properties of asphalt was explored from the molecular level. The modification mechanism of oyster shell powder modified asphalt was analyzed in detail from different scales by infrared spectroscopy, scanning electron microscopy, atomic force microscopy, dynamic shear rheology and viscosity tests. The results show that oyster shell powder has a significant effect on the mechanical properties of asphalt. When the content of oyster shell powder is 12 %, oyster shell powder has the greatest influence on the mechanical properties of asphalt.

Degradation characteristics of SBS polymer and its contribution to weathering aging of modified asphalt

Under the weathering environment, the aging behavior of SBS-modified asphalt (SBSMA) is complex, including oxidation of matrix asphalt, degradation of SBS, and disruption of SBS-asphalt interaction. However, most studies on the weathering mechanism of SBS-modified asphalt have mainly been considered from its overall perspective and based on environmental variables. In order to investigate the aging mechanism of SBSMA more clearly, the paper proposes a novel method of SBS-independent weathering to determine the aging behavior of SBS under accelerated weathering conditions and its effect on the performance of modified asphalt. Finally, by correlating its samples (M1) with the behavior of different fresh SBSMA(M2) and weathering aged SBSMA(M3), the SBS effective content equation under weathering conditions and the conversion coefficient between different aging methods were determined. Furthermore, by analyzing the physicochemical properties of SBS polymers before and after weathering and comparing them with the calculated results of SBS effective content within modified asphalt, it is discussed that the swelling effect of SBS under this method differs due to different aging levels, which affects the complete separation of matrix asphalt oxidation and SBS degradation. The macroscopic rheological behavior of samples was evaluated by dynamic shear rheology experiments (DSR), the variation of their chemical component and molecular weight were analyzed by Fourier transform infrared spectroscopy (FTIR) and gel permeation chromatography (GPC), and the microscopic network was observed by fluorescence microscopy (FM). The results illustrate that the degradation pattern of weathering SBS follows a single exponential decay function. The SBS effective content decreases to 66.7 %, 50 %, and 33.3 % after accelerated weathering for 5.8 h, 10.5 h, and 14.5 h, respectively. In addition, the conversion relationship between the effective content of SBS under two modes of SBS independent weathering aging and SBSMA weathering aging was established. The effective content of SBS within SBSMA at different service stages and its remaining modification capacity can be reasonably predicted by simple SBS weathering tests.

Modification effects of multi-walled carbon nanotubes on the mechanical and rheological properties of epoxy asphalt

Epoxy asphalt (EA) was widely used in road engineering fields, but previous research found that there were compatibility problems between epoxy (EP) and asphalt. In practical engineering applications, the compatibility of EA was improved by adding complex auxiliary agents. Although the composite of multi-walled carbon nanotubes (MWCNTs) and epoxy could improve the adhesion, corrosion resistance, and toughness of asphalt, it was difficult to achieve an excellent modification effect because of the agglomeration of MWCNTs. To improve the composite effect of epoxy and MWCNTs, carboxyl functional groups were added to MWCNTs under mixed acid conditions to reduce the agglomeration and achieve a better combination with epoxy. Then, MWCNTs/EP was prepared under physical stirring conditions. The MWCNTs/EP was observed by scanning electron microscopy (SEM), and it was found that MWCNTs could be uniformly dispersed in epoxy. To research the modification effect of MWCNTs on mechanical and rheological properties of EA, a variety of MWCNTs/EA with different proportions were prepared. The impact of different mixing ratios of MWCNTs/EP on the mechanical and rheological properties of asphalt was evaluated by dynamic shear rheological (DSR) experiments. The results showed that the addition of the appropriate amount of MWCNTs could further improve the high-temperature stability of EA. In this case, MWCNTs played a positive role in the modification of epoxy. However, the improper introduction of MWCNTs would have a negative weakening effect, which would weaken the high-temperature performance of EA. Through comparison, the optimal mixing ratios of MWCNTs and epoxy were finally determined as 6 % EP + 1.4 % MWCNTs and 20 % EP + 0.125 % MWCNTs.

Research on the Influence of Different Warm-Mix Modifiers on Pavement Performance of Bitumen and Its Mixture

Recently, bitumen pavements have been widely used for road paving. Various scholars have used modified bitumen in road paving to improve pavement performance, thus increasing the service life. In this study, Sasobit, XT-W3, and Evotherm were selected as warm-mix modified bitumen and various investigations including conventional performance, Brookfield rotational viscosity, dynamic shear rheology, Marshall stability, high-temperature rutting, water stability, low-temperature beam bending, fatigue, and compaction performance tests of modified bitumen mixtures were conducted to evaluate the pavement performance of modified bitumen and its mixtures. The effect of different warm-mix modifiers on high-temperature performance, temperature sensitivity, low-temperature performance, and water stability were compared and analyzed. The results indicated that incorporating Sasobit, XT-W3, and Evotherm modifiers enhanced the compressive properties, high-temperature rutting resistance, water stability, and fatigue resistance of the bitumen mixtures, whereas the Evotherm modifier reduced the deformation resistance of the bitumen mixtures. XT-W3 and Evotherm modifiers can effectively improve low-temperature cracking resistance, but Sasobit modifiers have a negative impact.

Rejuvenating Agents vs. Fluxing Agents: Their Respective Mechanisms of Action on Bitumen Subjected to Multiple Aging Cycles

During the service life of road pavements, the asphalt, more specifically the surface layer, is susceptible to aging due to the oxidation phenomenon and the loss of the volatile compounds of bitumen, which functions as the binder in the asphalt conglomerate. Road pavements that undergo a significant level of oxidation become rigid and susceptible to cracking, and new paving operations will need to be carried out in order to make the road ideal for continued use. However, due to recent eco-friendly initiatives that have been put in place to promote a circular economy and also mitigate the problem of environmental pollution, the asphalt industry is currently devising means of safeguarding the environment while also minimizing the cost of the production of road pavements without compromising their quality. As a general solution to this issue, old asphalt pavements are removed and recycled as reclaimed asphalt (RA), with the aim of restoring the original properties of the binder in such a way that RA can be re-used in combination with virgin materials to produce new road pavements. In this research study, virgin bitumen is subjected to a cycle of aging, after which two recycling agents are used to modify the aged bitumen samples. These samples containing the different recycling agents were subjected to a second aging cycle, a second recycling agent treatment, and then again subjected to a final aging cycle. The two recycling agents have different compositions, and each one of them could be either a rejuvenating agent or a fluxing agent. This study investigates the effect of these recycling agents on aged bitumen, and how the addition of these recycling agents influences the changes observed between virgin, aged and recycled bitumen. This would enable an understanding of rejuvenation and fluxing mechanisms, which will help in the classification of the asphalt recycling agents as either rejuvenating or fluxing agents. Dynamic shear rheology, atomic force microscopy, and light microscopy to determine asphaltene melting point were the techniques used in this investigation. The results obtained demonstrate that rejuvenating agents are more effective in reversing the effects of oxidative aging on the bitumen binder than fluxing agents.

Enhancing Bitumen Properties through Worm Mix Asphalt Additives: A Study on Physical and Rheological Characteristics

This study aimed to determine how various concentrations of warm mix asphalt (WMA) additives can affect the rheological and physical characteristics of asphalt cement. Bitumen was modified by the chemical additive PAWMA® with an addition ratio of (0.2, 0.4, and 0.6), while the organic additives, Sasobit® and Kaowax®, were added at concentrations of (2, 4, and 6%) by the weight of bitumen. Bitumen hardness, softness, temperature susceptibility, viscosity, and elastic behavior have all been measured using a variety of physical and rheological tests, such as the penetration degree, softening point, penetration index, rotational viscosity, and dynamic shear rheology. This study showed that bitumen physical and rheological properties were affected differently according to the type and percentage of the WMA additive employed. The PAWMA additive, for instance, raised the bitumen penetration while Sasobit® and Kaowax® decreased the bitumen penetration degree. The inverse occurred for the softening point values. All WMA additives lowered bitumen viscosity values. Results from a dynamic shear rheometer (DSR) showed that the rutting index value (G*/Sin) rose, indicating improved rutting resistance.

Effect and Mechanism of Rejuvenation of Field-Aged Bitumen Extracted from Reclaimed Asphalt Pavement

Due to wear and exposure to atmospheric agents, road pavements are subject to an inevitable aging process. Asphalt rejuvenating agents implement the reorganization of the colloidal structure of aged bitumen as well as the restoration of the correct asphaltene/maltene ratio. In recent years, several incentives have been put in place regarding conservation of resources and safeguarding the environment by avoiding waste and promoting a circular economy. Reclaimed Asphalt Pavement (RAP) is one of the ways to promote and implement circular economy practices. Recovery of bitumen from RAP conglomerate is a viable way of recycling aged bitumen for use in new pavements. Aged bitumen binder from RAP however needs to be rejuvenated in order to restore its virgin properties for it to be suitable for new paving operations. This paper evaluates the effectiveness of a rejuvenating agent on reclaimed asphalt pavement through both the analysis of the mechanical modulus and the inner micro- structural of the samples. These were conducted through Dynamic Shear Rheology (DSR), Atomic Force Microscopy (AFM), Differential Scanning Calorimetry (DSC) and light microscopy.

Polymerized activating highly-dispersible waste tire powder for viscoelasticity regulation of modified asphalt at a lower mixing temperature

This work explored polymerization activating fine waste tire powder modified asphalt at a lower mixing temperature. Different from common temperatures of more than 190 °C, traditional waste tire powder could not achieve the excellent properties of modified asphalt at 170 °C. Through styrene and methyl methacrylate monomers polymerized on the surface of 400-mesh waste tire powder, polymerized waste tire powder was successfully fabricated through changes in morphology and surface potential. Polymerized waste tire powder modified asphalt was 15 wt%. It was determined by dynamic shear rheology and nanoindentation. The excellent dispersion of polymerized waste tire powder in asphalt was proved by fluorescence microscopy. Compared with waste tire powder modified asphalt, the hardness of polymerized waste tire powder modified asphalt decreased by 21.27 %, and the viscoelasticity decreased by 92.26 %. It indicated polymerized waste tire powder modified asphalt performed good hardness and viscoelasticity regulation. This work inspired a new idea for modified asphalt and reclaiming waste tires, which would have good economic and environmental benefits.

Optimization design and performance evaluation of a novel asphalt rejuvenator

The development of a regeneration agent is one of the key technologies for pavement regeneration and one of the methods to reduce carbon emissions in the transportation field, so it is very necessary to develop a regeneration agent. Based on the composition of asphalt and rejuvenator components, the optimal dosing of extraction oil, plasticizer dioctyl phthalate (DOP), and hydrogenated (carbon 9) C9 petroleum resin was determined by the response surface method, and the suitable dosing of the anti-aging agent was also designed to optimize the orthogonal experiment to prepare the ZJ-I (Zenith Yummy-Invent) rejuvenator with good overall performance. On the basis of the ZJ-I rejuvenator, dynamic shear rheology (DSR), bending beam rheometery (BBR), Fourier transform infrared spectroscopy (FTIR), atomic force microscopy (AFM), and contact angle experiments were used to investigate the effects of the ZJ-I rejuvenator dosing on the high- and low-temperature rheology, chemical structure, surface microscopic morphology, and adhesion between asphalt and aggregate of aged asphalt and to explore the regeneration effect and regeneration mechanism of the ZJ-I rejuvenator. The results showed that the ZJ-I rejuvenator formulated with 83.6% extracted oil, 15% plasticizer DOP, 1.4% hydrogenated petroleum resin, 0.6% antioxidant, and 0.4% light stabilizer has the best regeneration effect, and its optimal dosing is 7% aging degree. It can also improve the adhesion performance of asphalt and aggregate.

A study on effect of oyster shell powder on mechanical properties of asphalt and multiple degrees of modification mechanism

In order to explore the effect of oyster shell powder on the mechanical properties of asphalt, in order to explore the modification mechanism of oyster shell powder on asphalt, based on matrix asphalt, this paper prepared oyster shell powder modified asphalt by adding oyster shell powder with fineness of 40 mesh to matrix asphalt according to 3%, 6%, 9%, 12%, 15% and 18%. Based on the theory of molecular dynamics, the effect of oyster shell powder on the mechanical properties of asphalt was investigated from the molecular level by establishing the molecular model of oyster shell powder modified asphalt with different contents. The modification mechanism of oyster shell powder modified asphalt was analyzed in detail from different scales by infrared spectroscopy, scanning electron microscopy, atomic force microscopy, dynamic shear rheology and viscosity tests. The results show that oyster shell powder has a significant effect on the mechanical properties of asphalt, and the incorporation of oyster shell powder has a positive effect on the improvement of asphalt technical performance. From the research of this paper, when the content of oyster shell powder is 12%, oyster shell powder has the greatest influence on the mechanical properties of asphalt and the best modification effect on asphalt.

Influence of chemically-modified cotton straw fibers on the properties of asphalt mortar

Cotton straw fibers have an important influence on the performance of asphalt mixtures. However, the modification of cotton straw fibers and the performance characterization between the treated cotton straw fibers and asphalt are still lack of understanding. To obtain a better performance improvement technical scheme of cotton straw fibrous asphalt mortar. In this study, sodium hydroxide, silane coupling agent (KH550), and glacial acetic acid (CH3COOH) were used to modify the surface of cotton straw fibers. The modification mechanism and basic properties of the cotton straw fibers were investigated. The effect of the modified fibers on the performance of asphalt mortar was studied using cone penetration, softening point, ductility, and dynamic shear rheology tests. The results showed that the CH3COOH- and KH550-modified fibers produce new acetyl C-O and Si-O deformation vibration absorption peaks, respectively. The three modification methods destroy the hemicellulose structure in the cotton straw fibers. The post-modification surface impurities, roughness, and basic properties of the fibers are reduced, increased, and improved, respectively. An increasing cotton straw fiber dosage continuously improves the high temperature performance of asphalt mortar, but reduces ductility. A fiber dosage of 2 % yields optimized the high temperature performance and the ductility. Under this dosage, the CH3COOH-modified cotton straw fibrous asphalt mortar exhibits a better comprehensive performance. Its shear strength and softening point, as compared to the matrix asphalt increase by 3.21 times and 14.99 %, respectively, and the ductility reduces by 23.94 %, all the measured properties meet the technical specifications of road petroleum asphalt. The results provide more bases for the application of cotton straw fibers in road engineering.