Increase In Softening Point Research Articles

Morphological characteristics of low-asphalt RAP and influence of its reaction product during combustion heating on regenerated asphalt

To provide reference for regeneration of the finely separated low-asphalt reclaimed asphalt pavement (RAP), the macroscopic and microscopic laboratory testing and quantum chemical simulation were combined. The morphological characteristics of the basalt and limestone low-asphalt RAP were analyzed. The low-asphalt RAP needs to be dried before regeneration, so the reaction mechanism and product of the asphalt film on its surface during drying were clarified. The product influence on the temperature resistance and fatigue performance of the virgin asphalt was studied, so as to consider their mixing during the subsequent regeneration process. Result shows that the gradation of limestone low-asphalt RAP is coarser and particles are slenderer than basalt with the same particle size grade. The 5–10 mm low-asphalt RAP particles are slenderer than those in the 10–20 mm grade. In the drying cylinder, asphalt basically generate no new functional groups below 200℃, while the asphalt film on the low-asphalt RAP surface undergoes pyrolysis to produce carbon black with the particle size around 100μm in the combustion heating area. The most easily oxidation or pyrolysis site in asphalt molecule is the carbon atom connected to the benzene ring. The pyrolysis of asphalt molecules to generate free radicals in the local oxygen deficient environment is the prerequisite for the carbon black formation, and pyrolysis requires higher temperature than oxidation because of its higher energy barrier. As the carbon black content increases, the penetration and ductility of asphalt decrease, the softening point increases, the high-temperature performance is enhanced, the low-temperature performance is weakened, and the fatigue performance is not significantly affected. As the particle size of carbon black increases, the decrease range in penetration, ductility and low-temperature performance of asphalt declines, the increase or improvement range of softening point and high-temperature performance enhanced, while the fatigue performance still shows no significant and regular change.

Laboratory aging method for simulating the extracted aged asphalt from reclaimed asphalt pavement

This study compared the performance of extracted asphalt and laboratory aged asphalt. The five-year service asphalt mixtures were used for extraction in this study. The laboratory aged asphalt experienced the Rolling thin film oven (RTFO) aging the Pressure aging vessel (PAV) aging with variable duration (5, 10, 15, 20, and 25 hours). By comparing the softening point, viscosity, and rheological properties of both, an aging simulation protocol was established. For laboratory aged asphalt binder, the softening point increases by 3.56 %, 5.68 %, 7.43 %, 8.16 %, and 8.74 % at PAV aging times of 5 h, 10 h, 15 h, 20 h, and 25 h, respectively. The rutting index and viscosity of the aged asphalt gradually increases with the PAV duration. There is a substantial increase in creep recovery rate and a significant decrease in non-recoverable creep compliance for aged asphalt. The rheological aging index demonstrates a linear increasing trend. The sulfoxide (SO) and aromatic (CO) aging indexes of the laboratory-simulated aged asphalt progressively rise with prolonged PAV aging time. The SO and CO aging indexes of the extracted asphalt consistent with RTFO aged asphalt experienced PAV aging 20 and 25 hours. The extracted asphalt can be simulated in the laboratory under standard RTFO conditions and a 22.26 hours PAV duration at a pressure of 2.1 MPa ± 0.1 MPa. This study introduces a methodology for simulating asphalt aging in an authentic service environment by adjusting the laboratory aging test conditions.

Physical and Rheological Properties of Coconut Waste Modified Bitumen

Numerous modifications have been made to bitumen to improve its durability and performance. This study aims to enhance bitumen by evaluating the physical and rheological properties of bitumen modified with coconut waste. The study develops bitumen samples modified with varying lengths and fiber content of coconut waste as a sustainable material. The samples were evaluated for rheological behavior using modern testing methods like the Dynamic Shear Rheometer (DSR) and Rolling Thin Film Oven (RTFO). F indings shows the penetration value decrease and the softening point increase with higher coconut waste content, suggesting the modified bitumen is more prone to deformation. The complex modulus G* increase significantly to 3872Pa for the 1% coconut fiber modified bitumen and 9771Pa for 1% coconut powder modified bitumen as compared to the control sample (3431Pa), indicating prospective higher resistance to rutting. In conclusion, modified with coconut waste, bitumen exhibits enhanced flexibility and reduced susceptibility to temperature-related issues. Unlike conventional bitumen, which often suffers from rutting and thermal cracking, this modified version shows improved resistance against shear stresses at elevated temperatures and retains greater flexibility in colder conditions.

Effect of recycled vegetable oil on the performance of nanomarl-modified asphalt mixtures

In response to the demand for a greener approach to pavement infrastructure and the economic benefits associated with alternative materials, the modification of neat binders has been a consistent focus. This research aimed to enhance the characteristics of asphalt binders and mixtures by incorporating recycled vegetable oil (RVO) and nanomarl. RVO was added to 60/70 penetration bitumen at concentrations of 1%, 3%, and 5% by weight, while nanomarl was kept constant at 5% by weight of the bitumen. Various physical, rheological, and microstructural properties of the modified binders were evaluated, including penetration, softening point, viscosity, rutting resistance, fatigue resistance, creep, stiffness, scanning electron microscopy (SEM), and Fourier transform infrared spectroscopy (FTIR). Furthermore, the moisture susceptibility and rutting resistance performance of asphalt mixtures incorporating these modified binders were investigated through analyses of tensile strength ratio and Hamburg wheel tracking. The test results revealed that the incorporation of RVO in bitumen led to a gradual increase in the penetration value of the modified bitumen. Simultaneously, the softening point and viscosity of the modified bitumen decreased, indicating that the addition of oil rendered the modified bitumen softer. However, the inclusion of nanomarl in RVO-modified bitumen improved its viscoelastic behavior and positively influenced its rheological properties under both unaged and aged conditions. Specifically, the addition of 5% nanomarl resulted in reduced penetration value, increased softening point, viscosity, rutting resistance, fatigue resistance, creep stiffness, and improved relaxation behavior at low temperatures. The most favorable outcomes were observed when incorporating 1% RVO with 5% nanomarl. Moreover, SEM and FTIR analysis demonstrated successful blending of the additives into the bitumen, without any evidence of phase separation. This indicates a homogeneous distribution of the additives within the bitumen matrix.Practical application: The modification of bitumen with waste or recycled oils for the production of asphalt mixture has been successfully studied in numerous researches. However, this study introduces a novel approach by synergistically combining recycled vegetable oil (RVO) modification with the incorporation of nanomarl particles into asphalt mixture. The innovation aspect lies in the integration of two sustainable and environmentally friendly components, RVO and nanomral, to enhance asphalt performance. The findings offer a blueprint for incorporating sustainable materials and approaches in road construction projects. Pavement engineers can adopt the use of RVO modification and nanomarl particles to create longer-lasting and environmentally friendly asphalt pavements. In regions with challenging climatic conditions, the use of this modified asphalt can lead to improved infrastructure resilience. Roads built with these materials can better withstand temperature fluctuations. The integration of RVO and nanomarl particles offers improved performance, cost-effectiveness, reduced environmental impact, and also opens avenue for further exploration and optimization of asphalt mixtures incorporating innovative additives.

Effects of thermo-oxidative aging on the macrophysical properties and microstructure of asphalt

To study the effect of thermo-oxidative aging on the physical properties and microstructure of base and modified asphalts, conventional index tests, dynamic shear rheology (DSR), differential scanning calorimetry (DSC), Fourier transform infrared (FTIR) spectroscopy, and gel permeation chromatography (GPC) were performed. The macro-physical indexes and microstructural changes in the asphalt before and after aging were analyzed. The results show that with an increase in the thermal-oxidative aging degree, the penetration degree of asphalt decreases; the softening point increases, and the high-temperature performance improves. Simultaneously, the asphalt consistency and hardness increase. This results in a significant increase in the initial modulus and glass transition temperature, decrease in the shear resistance, and degradation of the low-temperature performance. Rubber-modified asphalt exhibited the highest anti-aging performance, followed by styrene–butadiene–styrene-modified and 70# asphalts. Thermal-oxidative aging did not change the original functional group species; however, the peak area ratio of the sulfoxide and carbonyl functional groups increased significantly. After aging, the overall molecular weight of the asphalt shifted in the macromolecular direction. Weight-average and number-average molecular weights and polydispersity increased.

Improvements in Physical and Mechanical Properties of Asphalt by Addition of Low-cost Few-layers Graphene (FLG)

Physical and mechanical properties of asphalt have been improved by adding of few-layers graphene (FLG). FLG was obtained from a simple, low-cost and environmentally friendly liquid shear exfoliation method using a kitchen blender. The melted asphalt at temperature of 150oC was mixed with FLG at various concentrations (10 mg/ml, 20 mg/ml and 30 mg/ml) and contents (0 wt%, 3 wt%, 6 wt%, and 9 wt%) by weight of asphalt. The homogenized mixture was taken for penetration and softening point tests, while the mixing with aggregates was carried out for Marshall stability and asphalt concrete flow tests. The characteristics of void in mixture (VIM), void filled with asphalt (VFA), and void in mineral aggregate (VMA) were also investigated. The penetration values decreased (or the asphalt hardness increased) linearly with increasing of FLG concentration and FLG content. The softening point of asphalt increased as the increasing of FLG concentration and FLG content in asphalt with the average softening point increase of about 5%. The Marshall stability and asphalt concrete flow increased with increasing of FLG concentrations and FLG content. However, the addition of FLG did not affect the VIM, VFA or VMA values. Overall, the addition of FLG improves the physical and mechanical properties of asphalt and has promising prospects due to low-cost and eco-friendly nature of FLG.

The Utilisation of Polyethylene Waste Pyrolytic Wax as an Additive to Enhance the Performance of Virgin and Polypropylene-Modified Bitumen

Plastic addition to bitumen increases the stiffness of the binder, reduces its workability due to the increase in viscosity, and causes storage stability issues. Thus, plastic pre-treatment methods are needed. This research aims to address these shortcomings by developing a wax derived from the pyrolysis of polyethylene (PE) waste and investigating its efficacy as an additive in virgin bitumen and bitumen modified with recycled polypropylene (PP). Penetration, softening point, segregation, stress ratio, consistency, stiffness, and viscosity of the modified bitumen were measured. The interior structure and chemical changes of the proposed binders were also studied using a fluorescence microscope and Fourier-transform infrared spectroscopy (FTIR). When virgin bitumen is modified with 7% PE wax, its softening point increases (+ 15%), its viscosity is reduced (− 27%), and no segregation issue is observed. It also presented a stiffness increase (+ 32%) and better resistance to hot climates. Adding 7% of PE wax to bitumen modified with 5% PP reduces its viscosity by 70% and segregation by 26% while increasing its stiffness and rutting resistance in comparison to the bitumen solely modified with PP. These results reveal that, in addition to enhancing bitumen properties, the proposed substance reduces compaction and mixing energy requirements.

Performance of asphalt mortar with recycled concrete powder under different filler-to-asphalt weight ratios

The feasibility of using recycled concrete powder (RCP) as fillers in asphalt mortar is investigated in this study, to achieve a sustainable and economical asphalt production. The differences in physical properties between limestone powder (LSP) and RCP are analyzed and compared. Moreover, the interactions of LSP and RCP with asphalt are studied as well. The properties of asphalt mortar studied include ductility, softening point, penetration, viscous and elastic behaviors of asphalt mortar. Compared to LSP, the RCP presented a rougher surface, additional pores, more complex pore structures, larger Brunauer, Emmett and Teller (BET) surface areas, and smaller particle size. At 0.6 and 0.9 of filler-to-asphalt weight ratio (F/A), the RCP is more effective for the performance enhancement of asphalt mortar compared with the LSP. When the F/A is 0.9 and LSP is completely replaced by RCP, the 15 °C penetration index (PI) and ductility of asphalt mortar decrease by 9.3% and 29.2% respectively. The softening point increases by 5.4%. By contrast, the RCP causes a considerable decrease in PI, equivalent brittle point (T1.2) and ductility when F/A ratio is 1.2. After RCP completely replace LSP, the PI, T1.2, and ductility of asphalt mortar decrease by 47.1%, 44.0%, and 29.0%, respectively. However, at F/A of 0.6, the asphalt mortar with 100% RCP replacement ratio presented both acceptable ductility and plasticity. Under the same temperature and F/A, the complex shear modulus G* and rutting resistance factor G* /sinδ of asphalt mortar raise with the increase of RCP replacement, which indicates that the RCP can better enhance the high-temperature rutting resistance of asphalt mortar than the counterpart LSP. It also implies that the modification of LSP and RCP in asphalt mortar mainly depends on the physical interactions rather than the chemical reactions.

Influence of salt dissolution on durable performance of asphalt and Self-ice-melting asphalt mixture

At present, research on the influence of salt dissolution on pavement performance of self-ice-melting asphalt mixture is scarce. Based on laboratory research, this study aims to investigate the influence of salt dissolution on the durable performance of asphalt and self-ice-melting asphalt mixture. Firstly, SBS modified asphalt binder containing Mafilon (MFL) and self-ice-melting asphalt mixture (SMA-13) containing MFL and rubber particles (RP) were subjected to dry-wet cycles for different cycles. Then the influence of salt dissolution on the properties of asphalt and its mechanism were studied by physical properties test, scanning electron microscopy (SEM) test, energy dispersive spectrometer (EDS) test and Fourier transform infrared spectroscopy (FTIR) test. Finally, the influence of salt dissolution degree on long-term pavement performance of asphalt mixture was evaluated by freeze–thaw splitting test, rutting test, and trabecular bending test. The experimental results showed that with the increase in the number of dry-wet cycles, the penetration and ductility of asphalt decrease, while the softening point increases. The greater the content of MFL and the increasing number of dry-wet cycles, the greater the variation is. The effect of salt dissolution on asphalt properties can be attributed to salt aging and physical effect, without chemical reactions occurring. In addition, the road performance test of asphalt mixture indicated that the decrease of water stability, high-temperature performance, and low-temperature performance of self-ice-melting asphalt mixture increases firstly and then tends to be gentle as the increase of salt dissolution. What’s more, the water stability is deeply influenced by salt dissolution.

The Application of Nano-Calcium Carbonate in the Technology of Improving Road Petroleum Asphalt

Nano-calcium carbonate is a new type of nanomaterial, which has great influence in many fields. In order to explore the influence of nano-calcium carbonate on petroleum asphalt, an experiment was designed to analyze the application of nano-calcium carbonate in improving road petroleum asphalt technology. This article explores the methods of preparing nano-calcium carbonate and petroleum pitch, understands the characteristics of the two materials, and then draws two methods of mixing nano-calcium carbonate and petroleum pitch: one is freezing and disintegrating, and the other is stepwise mixing fusion. In this paper, the fusion-modified asphalt is subjected to grouping experiments on the prediction model and “three indicators.” The experimental results show that with the increase in nano-calcium carbonate, the ductility of the modified asphalt decreases, the softening point increases, and the penetration is 15% reaching the maximum value. Nano-calcium carbonate is very suitable for improving road petroleum asphalt.

Thermal ageing mechanism of a natural rock-modified asphalt binder using Fourier Transform Infrared Spectroscopy analysis

In this paper, Fourier-transform infrared (FTIR) spectroscopy was used for the microanalysis of base asphalt modified with natural rock asphalt as the asphalt modifier. A Pen 70 asphalt was selected and natural rock asphalt modifiers (2%, 4%, 6%, and 8%) were added to prepare different asphalt samples. Macroscopically, the performance indexes of five kinds of asphalt before and after short-term ageing and the changes of each index with the content were tested. The changes in characteristic functional groups of natural rock modified asphalt before and after thermal ageing were analyzed by FTIR. The ageing degree of asphalt was judged by qualitative and quantitative analysis, and the ageing behavior and mechanism of asphalt were revealed from the microscopic point of view, establishing the relationship between macro and micro, combined with the Dynamic Shear Rheometer (DSR) test. The results showed that, with the increase of the content, the penetration and ductility decrease, and the softening point increases, indicating that the viscosity and thermal stability of asphalt increase after adding natural asphalt. The asphalt before and after short-term ageing follows this law. The short-term ageing process was mainly characterized by physical compatibility and volatilization of light components. A small amount of carbonyl group was formed, and a small number of components were dehydrogenated to olefin. In the long-term ageing process, the long-chain hydrocarbon decomposition of the polymer generated alkyl (CH3), and the polar molecule reacted with oxygen to generate a large number of carbonyl groups (C=O) and sulfone groups (S=O). In addition, according to the carbonyl index CI and sulfoxide index SI, the ageing degree of the modified asphalt was less than that of the base asphalt. Meanwhile, it can be determined that the carbonyl index was the smallest and the ageing resistance was the best when the content of natural rock is 6%.

Research on the Rheological Properties of Asphalt Binder Modified by Fume Silica and Crumb Rubber Compound

This study investigates the effect of using Fume Silica (Aerosol 300) alone and together with crumb rubber (CR) in bitumen modification on the traditional and rheological properties of the binder and compares it to the SBS modified binder. Using the aerosol additive in the binder at the rates of 0.5%, 1%, 1.5%, and 2% were determined as the most convenient ratio and CR+aerosol modified binders were prepared per this ratio. The binders were subjected to the softening point, viscosity, frequency sweep, bending beam rheometer (BBR), and Fourier Transform Infrared spectroscopy (FTIR) tests in the context of the study. Besides, the optimum conditions were determined according to the response functions by designing an experiment with statistical regression according to the Response surface methodology (RSM). The results indicate that the optimum aerosol ratio is 1.5%. With the use of 1.5% aerosol in 6% CR modification per bitumen weight, it was found that (1) the softening point increases and the temperature sensitivity decrease in comparison to other binders, (2) the consistency of the binder increases, (3) the complex modulus values increase and become more resistant to rutting, (4) the low-temperature parameters enhance by performing more flexible behavior, (5) there may be physical changes in the structure even though there is no chemical reaction in the binder with the use of CR and aerosol additives, and (6) the experimental data and theoretical data obtained from the RSM method are consistent as per the statistical analysis.

Synthesis, characterization and utilization of zinc oxide/expanded vermiculite composite for bitumen modification

The multi-dimensional nanomaterial modifier composed of nano-zinc oxide (nano-ZnO) and expanded vermiculite (EVMT) can significantly improve resistance to thermo-oxidative and ultraviolet radiation aging and road performances of bitumen. However, the nano-ZnO particles are susceptible to agglomeration and the homogeneity between nano-ZnO particles and EVMT is hard to be achieved in bitumen. In the study, a new bitumen modifier, a combination of ZnO particles and EVMT, was developed by composite technology to reduce or avoid the agglomeration of the ZnO particles and generate a synergistic effect on bitumen properties, especially for the aging resistance of bitumen. The newly developed modifier was synthesized with a modified hydrolytic precipitation method and characterized by X-ray diffractometer (XRD), field emission scanning microscope (FESEM), Fourier transform infrared spectrometer (FTIR), and UV–Visible spectrometer. Further, the modified bitumen was prepared and then aged with thin-film oven aging test (TFOT), pressure aging vessel (PAV), and ultraviolet (UV) radiation aging methods, respectively. Finally, the effects of modifiers on physical, rheological, and aging resistance of bitumen were evaluated. Results showed that with the synthesis operation, ZnO particles homogeneously loaded on the surface of EVMT, greatly restraining ZnO particles agglomeration and achieving the homogeneity between ZnO and EVMT. Furthermore, due to higher softening point, ductility, and complex modulus values for the modified bitumen compared with that of unmodified bitumen, the introduction of the newly developed modifier can potentially enhance the low-temperature tensile properties and deformation resistance of bitumen. Meanwhile, when the bitumen is exposed to various environmental factors, such as heat, oxygen, and UV radiation, the composites modifier in bitumen can synergistically play a role in reducing the effects on bitumen aging. For that, regardless of aging methods, the introduction of ZnO/EVMT into bitumen can efficiently retard its softening point increase and mobility deterioration, namely, hinder bitumen aging. Therefore, the newly developed modifier, ZnO/EVMT, is promising in both resisting bitumen aging and improving bitumen properties at low and high temperatures, and thus a longer service life for bitumen pavement can be expected with its application.

Modeling and optimization of mixing parameters using response surface methodology and characterization of palm oil clinker fine modified bitumen

One of the major biomass wastes discarded in large volumes from the palm oil mill is the palm oil clinker (POC) chunks. Thus, the need to develop strategies to promotes cleaner production is crucial for environmental sustainability. The present study aims to ascertain the viability of using palm oil clinker fine (POCF) as a bitumen modifier to improve conventional properties. To achieve this aim response surface methodology (RSM) was utilized to evaluate the influence of POCF dosage and mixing parameters on the conventional properties (penetration, softening point, and penetration index) of the POCF-modified bitumen (POCF-MB). By utilizing the central composite design (CCD) process, a quadratic regression model was considered with a p-value < 5% for all responses at the globalize optimum conditions. ANOVA analysis reveals that POCF dosage and mixing time show a substantial effect on the bitumen's properties in comparison with the mixing speed and temperature. After optimization, the optimal POCF dosage was 7.75%, and mixing parameters for temperature, speed, and time are 140 °C, 1000 rpm, and 51.9 min respectively. At optimum POCF dosage and mixing parameters, the percentage error between the RSM predicted and laboratory values was < 5% for all responses. The modification produces a stiffer bitumen blend, which causes a decrease in penetration with an increased softening point. Subsequently, the characterization of the POCF-MB blend was assessed for the multi-objective optimization optimum input parameters via Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), and Scanning electron microscope/energy dispersive x-ray (SEMEDX). Results of characterization show that POCF significantly influences the bitumen's conventional properties. The study findings show that POCF has great potential as an alternative bitumen modifier to promote sustainability.

Compatibility and Adhesion Properties of Rubber Asphalt

To research the compatibility and adhesion of rubber asphalt, the correlation of the asphalt components and rubber content with conventional properties of rubber asphalt was analyzed. The effects of asphalt component, rubber content, thin-film oven testing, and ultraviolet (UV)-aging testing on the adhesion properties of rubber asphalt were analyzed by measuring the surface free energy and its component based on the theory of surface free energy. Results show that the three major indicators of rubber asphalt are obviously affected by the properties of matrix asphalt, i.e., rubber asphalt has low penetration, high softening point, and movement viscosity processed by the matrix asphalt with high resin and asphaltene content. With increased rubber content, the penetration of rubber asphalt decreases and its softening point increases, but its ductility value is closer. Viscosity decreases when rubber asphalt is stored at high temperature, and viscosity decreases by 60% when stored for 8 h at 180℃. The surface energy of rubber asphalt increases with increased rubber content. After thin-film oven testing of 5, 10, and 15 h, the surface energy of rubber asphalt increases, but the change rate of surface energy decreases. The effect of UV aging on the surface properties of rubber bitumen is not obvious. The surface energies of rubber asphalt processed by different components of matrix asphalt after 10 and 20 d of UV aging differ.

Study on the Relationship between Nano-Morphology Parameters and Properties of Bitumen during the Ageing Process.

Thermo-oxidative ageing is one of the main factors affecting bitumen performance. At present, the research on bitumen ageing has entered the micro stage. The purpose of this paper was to study the relationship between nano-morphology parameters and properties of bitumen of bitumen during the ageing process. To this end, bitumen with different ageing degrees was prepared in this paper, and Atomic force microscopy samples with different cooling rates were prepared. The relationship between ageing degree of bitumen and nano-morphology parameters was analyzed. A functional relationship model between nano-morphology parameters and properties of bitumen was established. The results show that the percentage of bee-like structure area (), maximum amplitude () and roughness () increased with the increase of ageing degree. the percentage of bee-like structure area, the maximum amplitude and the roughness increase with the increase of cooling rate. With the increase of the percentage of bee-like structure area, the maximum amplitude and the roughness, the viscosity of bitumen at 60 °C increases, penetration decreases, and softening point increases. There is a nonlinear relationship between the nano-morphology parameters and properties of bitumen.

Application of Zeolite Tuffs as Mineral Filler in Warm Mix Asphalt.

Zeolite materials are used in the warm mix asphalt technology as an asphalt foaming additive, which partially replaces the filler. This article analyzes the influence of the zeolite and other fillers addition on the properties of mastic asphalt. In the research, 35/50 penetration grade asphalt and three types of fillers were used: lime filler (L), zeolite tuff (clinoptilolite) (C), hydrated lime (H) and their mixed combinations (C:L in 1:1 and 1:3 proportions as well as C:L:H in 2:2:1 ratio). The characteristics of the materials included: chemical analysis, phase composition and particle size distribution. The following properties were determined on the asphalt mastic samples: penetration, softening point, penetration index, dynamic viscosity and stiffening measured by softening point increase. It was found that clinoptilolite could partially replace the traditional lime filler, without a negative impact on the asphalt mastic properties. Additionally, the hydrated lime inclusion should have a positive effect on the frost resistance of an asphalt mix.

High temperature rheological properties of APAO and EVA compound modified asphalt

This study aims to explore the laboratory performance of APAO (Amorphous Poly Alpha Olefin) and EVA (ethylene-vinyl acetate copolymer) compound modified asphalt. Four EVA concentrations (i.e., 0%, 2%, 4%, and 6% by the weight of base asphalt) and four APAO concentrations (i.e., 0%, 2%, 4%, and 6% by the weight of base asphalt) were selected. Conventional tests (penetration, softening point, ductility and viscosity) were conducted. Frequency sweep, temperature sweep and multiple stress creep recovery (MSCR) tests were carried out to investigate the rheological properties of the asphalt binders and the storage stability was measured by cigar tube tests. The aging effect was evaluated by using dynamic shear rheometer (DSR) testing results. Fourier transform infrared spectroscopy (FTIR) test was used to study the chemical reaction of the asphalt. The results represented that the addition of additives (i.e., APAO and EVA) decreased the nonrecoverable creep compliance and aging index while increased softening point, elastic recovery, complex modulus and recovery rates, which indicating that APAO and EVA enhanced the high temperature properties of asphalt. Specially, in the ductility test at 5℃, the addition of APAO/EVA greatly improved the crack resistance at low temperature. The increasing VTS (viscosity-temperature susceptibility) indicated the additives enhanced the resistance to temperature susceptibility of this compound modified asphalt. Besides, the binder with APAO is better than that with EVA alone, especially in the elastic recovery and aging effect. Besides, the storage stability test results showed that the increase of APAO improved the stability of asphalt and the compound modified asphalt binders showed good resistance to cracking at low temperature in ductility test at 5 °C. The FTIR test showed that chemical reactions might happen during the mixing process of asphalt.

Research on properties of bitumen mortar containing municipal solid waste incineration fly ash

Studying the property of bitumen mortar is essential in becoming more acquainted with the pavement performance of the bitumen mixture. In this paper, the leaching test carried out on the bitumen mortar containing municipal solid waste incineration (MSWI) fly ash indicated that this process could obtain new materials without significant hazards to the environment. Some characterizations of bitumen mortar containing MSWI fly ash, which was used to replace the traditional limestone mineral filler (LMF) in bitumen mortar, were investigated. The softening point, penetration test, dynamic shear rheometer (DSR), bending beam rheometer (BBR), Brookfield viscosity test, and the scanning electron microscope (SEM) were carried out to evaluate the effects of MSWI fly ash on bitumen mortar properties. The experimental results demonstrated that adding MSWI fly ash resulted in reduced penetration, phase angle (δ), and creep rate (m) while resulted in increased softening point, complex shear modulus (G*), rutting factor (G*/sinδ), and creep stiffness (S). This indicated that MSWI fly ash- bitumen mortar had a negative influence on the low temperature properties but a positive impact on the high temperature properties compared with LMF- bitumen mortar. However, the negative effect of MSWI fly ash-bitumen mortar on the low temperature properties was negligible. Owing to the advantage of MSWI fly ash-bitumen mortar in environmental effects, energy conservation, and excellent performance, further research is needed about MSWI.

Plastic bag waste modified bitumen a possible solution to the Algerian road pavements

Many Algerian road and highway pavements suffer from severe premature degradations that appear in the first years of their in-service life because of the insufficient performance of the asphalt pavement materials. This study examines the suitability of using plastic bag waste as a bitumen modifier in order to improve the behaviour of asphalt mixes. This paper analyses the effect of adding plastic bag waste; low density polyethylene (LDPE), to a conventional 40/50 graded bitumen. Basic rheological parameters such as penetration, softening point, ageing (RTFOT) and storage stability were used to determine the plastic addition resulting changes on the modified bitumen, expressed relatively to the pure bitumen basis. FTIR spectroscopy was also used to study the chemical functionalities present in the modified bitumen. It was observed that the penetrability of the waste plastic modified bitumen (WPmB) decreases and its softening point increases. Consequently, its thermal susceptibility and its aging rate decrease. Performances of the WPmB were then determined on an asphalt concrete mix (AC) in terms of mix compaction behaviour, stiffness modulus and water resistance ameliorations. Results obtained show that adding plastic waste to the pure bitumen allows reducing void content of the mix and increasing substantially its stiffness modulus and water resistance.