Modified Asphalt Research Articles

Research on Rheological Properties by Desulfurized Rubber Powder/SBS Composite-Modified Asphalt and Road Performance of Its Mixture

Desulfurized rubber powder and SBS were used as asphalt modifiers to study the rheological properties and performance of desulfurized rubber powder/SBS composite-modified asphalt (DR/SBSCMA). First, the basic performance indicators such as penetration, ductility, softening point, and viscosity were studied. Second, the high-temperature and low-temperature rheological properties of asphalt were evaluated by using a dynamic shear rheometer (DSR) and bending beam rheometer (BBR). Finally, their high-temperature stability, low-temperature crack resistance, and water stability under the gradation of AC-13 and SMA-13 were evaluated. The results show that DR/SBSCMA had great advantages in terms of ductility and softening point, especially the softening point, which reached 90°C. It also demonstrated excellent high-temperature performance and tensile strength, and penetration was slightly lower than that of SBS-modified asphalt. Moreover, after compound modification, high-temperature and low-temperature rheological properties were effectively improved, and DR/SBSCMA adequately met the requirements of PG82-34. In addition, DR/SBSCMA maintained excellent high-temperature stability in both AC-13 and SMA-13 mixtures, coupled with obvious improvements in rutting deformation. Meanwhile, its low-temperature cracking resistance is slightly lower than that of SBS-modified asphalt, but both adequately meet the specification requirements. Ultimately, the water stability of DR/SBSCMA is comparable to that of SBS-modified asphalt, with both reaching more than 90%, proving its excellent water stability.

Analysis of the Influence of Production Method, Plastic Content on the Basic Performance of Waste Plastic Modified Asphalt.

The sustainable reuse of waste plastic as an alternative construction material has numerous environmental and economic advantages. New opportunities to recycle waste plastic in asphalt for road construction would mitigate landfill issues and significantly reduce global carbon emissions. With a clear aim to contribute to a more efficient reuse of waste plastic, this paper reutilized two types of waste plastic (polypropylene (PP) and polyethylene (PE)) as asphalt modifiers to improve the performance of asphalt pavement as well as to achieve the purpose of sustainable recycling waste plastic. Therefore, the optimal preparation parameters of plastic-modified asphalt were recommended by the orthogonal test. Then, the dispersion and modification mechanisms of plastic particles in plastic-modified asphalt were further studied by Fourier Transform Infrared Spectroscopy (FTIR) and Thermogravimetric Differential Scanning Calorimetry (TG-DSC). The results show that the asphalt containing PP and PE shows better overall performance at high temperatures compared with the base asphalt. Furthermore, PE-modified asphalt and PP-modified asphalt exhibited optimal properties when prepared at 3000 rpm for 30 min at 170 °C. Moreover, the results of the expansion mechanism show that the main reaction process of plastic asphalt is a physical change. Finally, PP-modified asphalt and PE-modified asphalt generally perform well and are suitable for high-temperature areas. Consequentially, the results of this research promote the recycling of waste plastic, ultimately advocating the recycling of waste materials and environmental protection of pavement construction.

Analysis of thermal susceptibility and rheological properties of asphalt binder modified with microwave activated crumb rubber

Using crumb rubber (CR) as an asphalt modifier not only realizes the recycling of waste tire resources, but also significantly improves the asphalt pavement performance. However, crumb rubber modified asphalt (CRA) prepared by wet process has poor thermal storage stability and microwave activation is an effective way to improve thermal stability. The main purpose of this paper is to compare the temperature susceptibility and rheological characteristics of microwave-activated crumb rubber modified asphalt (MCRA) and CRA. The scanning electron microscopy (SEM) was used to characterize micro morphology of CR particles after various microwave radiation time. The frequency sweep test, multiple stress creep and recovery (MSCR) test, and linear amplitude sweep (LAS) test were conducted and Cole-Cole diagram, Black diagram as well as master curve also were used to analyze rheological properties of modified asphalt. And the modified asphalt segregation experiment and solubility were also performed to verify the improvement effect of microwave activation. The results show that microwave activation makes CR surface rough and increases its specific surface area. And the Cole-Cole diagram and Black diagram both show that CR/MCR improve the elasticity of base asphalt, and the elasticity of MCRA is lower than CRA, as well as the h value proves that the microwave activation strengthens the polymeric network of asphalt. Solubility and storage stability experiments directly demonstrate that microwave activation can promote the dissolution of CR and reduce the segregation of CR in asphalt. The phase angle master curve is more sensitive to the variation of the internal structure of CRA/MCRA than complex modulus master curve, and the plateau zone in phase angle master curve illustrates the entanglement and interaction within the modified asphalt. The addition of CR/MCR reduce the thermal sensitivity of modified asphalt, and improve high-temperature anti-rutting and medium-temperature anti-fatigue properties. Considering high temperature and fatigue characteristics, the optimal content of MCR in MCRA is 20%–25%.

Performance of glass powder as bitumen modifier in hot mix asphalt

The disposal of glass bottles in landfills has been an ongoing global environmental issue that is yet to be resolved. Using discarded glass in the asphalt mixture may assist in easing the strain on environmental authorities. In this experiment, the discarded glass bottle was repurposed to create glass powder, which was subsequently used as a potential modifier material in an asphalt binder. This study aims to evaluate the characteristics of modified asphalt binders that incorporate glass powder from waste glass bottles. The asphalt binder with a 60/70 penetration grade was used. Bitumen was mixed with varying percentages of glass powder (0, 2, 4, 6, 8 and 10%). The characteristics evaluation using Fourier-transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), X-ray fluorescence (XRF), Field emission scanning electron microscopy (FESEM), Scanning electron microscopy (SEM), softening point, penetration test, penetration index, and Marshall tests were performed. The main oxide group found in glass powder was contributed by silicon oxide (SiO2). The FESEM morphology analysis showed that the glass powder texture was dense, compact, and contained high contents of Silica (Si) and Oxygen (O) forming silicon dioxide (SiO2). Results showed that adding 2% and 4% of glass powder to bitumen lowered the bitumen's softening point and increased its heating loss compared to the unmodified sample. The Marshall stability of the asphalt mixture was significantly improved with the addition of glass powder.

Study on Adhesion Property and Moisture Effect between SBS Modified Asphalt Binder and Aggregate Using Molecular Dynamics Simulation.

In this project, the adhesion property and moisture effect between styrene–butadiene–styrene (SBS) modified asphalt binder and aggregate were studied to reveal their interface adhesion mechanism. The influence of SBS contents on adhesion property and moisture effect between binder and aggregate phases were investigated using molecular dynamics simulation. Moreover, the double-layer adhesion models of asphalt binder–aggregate and triple-layer debonding models of asphalt binder–water–aggregate were constructed and equilibrated, and the adhesion property and the moisture effect were evaluated numerically. The results indicate that the built SBS-modified asphalt binder models show favorable reliability in representing the real one. The variation in the work of adhesion for SBS modified asphalt binder–quartz is not remarkable with the SBS content when its content is relatively low. However, the work of adhesion decreased significantly when the content was higher than 6 wt.%, which is consistent with the experimental results. The adhesion between SBS-modified asphalt binder and quartz is derived from Van der Waals energy. The modified asphalt binder with a high SBS modifier content (8 wt.% and 10 wt.%) shows much better moisture resistance (nearly 30% improved) than the unmodified asphalt binder from the work of debonding results. According to the Energy Ratio (ER) values, asphalt binders with high SBS content (8 wt.% and 10 wt.%) present a good moisture resistance performance. Therefore, the SBS content should be seriously selected by considering the dry and wet conditions that are used to balance the adhesion property and debonding properties. The content of 4 wt.% may be the optimal content under the dry adhesion and moisture resistance.

Recent development, utilization, treatment and performance of solid wastes additives in asphaltic concrete worldwide: A review

Asphalt modifications either involved commercial or recycled waste materials modifiers help optimise and improve the deficient properties of asphalt mixtures relative to current standards. This manuscript reviews the recycling of waste materials generated from various sources such as household, agricultural and industrial to minimise natural resources exploitation, lower energy demand, and enhance overall pavement performance. The actual development and implementation of recycled asphalt pavement in numerous countries in Asia, North America, South America, Europe and Africa are emphasised, and their influence on the performance of asphalt pavements is reviewed. Modified pavement showed satisfying performance for years as maintenance and restoration are not required. Generally, solid wastes are required to undergo pre-requisite treatments via mechanical, biological stabilization, thermal or chemical methods before the implementation as asphalt modifiers to ease the handling process. Moisture damage issues have been spotted in the implementation of several types of solid wastes and consequently reduced the strength and durability of pavement. Therefore, potential hydrophobic treatment can be adopted to improve the quality of asphalt mixtures by modifying the hydrophilic characteristics that are contributed by the hydroxyl groups on the cellulose nanocrystals (CNCs) or providing a superhydrophobic coating onto the particles. The treatments greatly weakened the moisture sensitivity of modified materials by reducing their water absorption and increasing their water contact angle. The modified mixtures are necessary to have identical or enhanced pavement performance to the conventional mixtures. Besides, future researchers are encouraged to broaden the research field in pavement engineering by considering chemical treatments in improving material properties to achieve cost-saving, efficient waste management, and higher commercial feasibility. Before implementing any virgin materials, waste materials and by-products as alternative substances or modifiers, it is strongly advised to consider the environmental and economic impacts of the material properties and their optimal incorporation. • The applications of solid waste materials modifiers in asphalt modification were reviewed. • Various sources of waste materials were adopted in experiments and field studies. • Prerequisite treatments are necessary to prolong the service life of asphalt pavements.

Effect of SBS and crumb rubber on asphalt modification: A review of the properties and practical application

Owing to the environmental protection potential and the desirable high performance capabilities, asphalt rubber (AR) and styrene-butadiene-styrene (SBS) modified asphalt have been widely used. However, the poor construction workability and segregation issues of AR, along with the exorbitant cost of SBS modified asphalt, are of the serious problems that plague their application scope. Moreover, SBS/crumb rubber (CR) modified asphalt is gradually becoming widespread and it therefore becomes incumbent to find appropriate ways to mitigate the issues that may limit its use. As a consequence, it becomes crucial to analyze the interaction between CR and SBS modifiers in the composite mixture, as well as evaluate the influence of modifier dosage on the performance of the modified asphalt. This study presents a comprehensive review of the effects of SBS modifier, CR modifier and composite SBS/CR on the performance of modified asphalts. Macro analysis and micro analysis, including analysis on the conventional physical properties, are carried out. It can uncover the interaction between modifier and asphalt, which reveals how the modifiers influence the properties of modified asphalts. This study will serve as a source of invaluable information to researchers, engineers, and designers, informing them the development, potential and challenges of the CR, SBS and SBS/CR modified asphalts, the optimum contents to attain the best performance along with the mechanism involved.

Study on the Influence of Nano-OvPOSS on the Compatibility, Molecular Structure, and Properties of SBS Modified Asphalt by Molecular Dynamics Simulation

The present research is carried out to inspect the influence of nano-OvPOSS (octavinyl oligomeric silsesquioxane) with different particle sizes on styrene-butadiene-styrene (SBS) modified asphalt through the method of molecular dynamics simulation. This nanomaterial is investigated for the first time to be used in asphalt modification. With the construction of modified asphalt simulation models and the analysis of their mixing energy, radius of gyration (Rg), radial distribution function (RDF), ratio of free volume (RFV), heat capacity, bulk modulus, and shear modulus, this study elucidates the influence of nano-OvPOSS on the compatibility between SBS and asphalt, on the structure of SBS as well as that of asphalt molecules and on the temperature stability and mechanical properties of SBS modified asphalt. The results show that nano-OvPOSS not only is compatible with SBS as well as with asphalt, but also is able to improve the compatibility between SBS and asphalt. Nano-OvPOSS is able to reinforce the tractility of branched chains of SBS and make SBS easier to wrap the surrounding asphalt molecules. The free movement space of molecules in the SBS modified asphalt system also shrinks. Moreover, the addition of nano-OvPOSS into SBS modified asphalt results in higher heat capacity, bulk modulus, and shear modulus of modified asphalt. All of these effects contribute to a more stable colloidal structure as well as more desirable temperature stability and deformation resistance of the modified asphalt system. The overall results of the study show that nano-OvPOSS can be used as a viable modifier to better the performance of conventional SBS modified asphalt.

Evaluation of Volumetric Properties of Cassava Peel Ash Modified Asphalt Mixtures

In continuance to providing a reliable and cost-efficient road construction material that would aid the development of sustainable pavements while also eradicating agricultural wastes to protect the environment, Cassava Peel Ash (CPA) modified asphalt mixture is seen to be one of the most viable options. This study aimed to determine the suitability of Cassava Peel Ash (CPA) in hot mix asphalt for improved pavement performance. Using response surface methodology, a central composite design was employed for the mix design parameters, namely coarse aggregate (CA), fine aggregate (FA), mineral filler (MF), bitumen content (BC), and cassava peel ash (CPA). CPA was used as a partial replacement for filler and varied between 0% and 20%. The BC varied between 4% and 8%, the MF varied between 15% and 20%, the FA varied between 10% and 14%, and the CA varied between 46% and 52%. The interactive effect between the mix design parameters on the volumetric properties of the asphalt mixtures was evaluated. The results obtained showed the Marshall stability, flow, density, volume of the void, and void in mineral aggregates of the asphalt mixtures at 1.8037–8.045 kN, 2.7-8.22 mm, 2.0426–2.3909%, 1.094–7.966% and 55.5105–93.1393% respectively. These results indicate that the interaction of CA, FA, MF, BC, and CPA influences the volumetric properties of asphalt mixtures. From the RSM analysis, a prediction model and an optimal condition of 4.018% asphalt content, 20% cassava peel ash, 46% coarse aggregate, 10% fine aggregate, and 15% mineral filler were achieved for the asphalt mixtures. Doi: 10.28991/CEJ-2022-08-10-07 Full Text: PDF

Optimizing Regenerant Content of Aged SBS Modified Asphalt Binder Based on High- and Low-Temperature Performance

The performance of the recycled asphalt pavement is directly influenced by the content of the used regenerant (i.e., rejuvenator and/or unaged asphalt binder). The goal of this study is to optimize regenerant content of aged styrene-butadiene-styrene (SBS) modified asphalt binder based on high-temperature creep and low-temperature relaxation performance tests. Initially, penetration, ductility, softening point, multiple stress creep recovery (MSCR), and bending beam rheometer (BBR) tests were carried out to investigate the rheological behavior of the aged SBS modified binder (AMB) regenerated with different contents of the rejuvenator and unaged SBS modified binder (UMB). A method is proposed, based on the rheological behavior of the regenerated AMB, to determine the optimum contents of the regenerants (i.e., rejuvenator and UMB). To reach a successful trade-off between low- and high-temperature properties of the regenerated AMB, the relaxation rate VR and nonrecoverable creep compliance J3.2 (at 3.2 kPa) were selected as the evaluation indices to settle the optimum contents of the rejuvenator and UMB. The results showed that the ductility of regenerated AMB is on par with the UMB when the contents of rejuvenator and UMB are 4% and 70%, respectively. The nonrecoverable creep compliance and relaxation rate of the regenerated AMB tended to increase with the increase in the content of the rejuvenator and UMB, whereas the recovery rate and relaxation modulus decreased. It indicated that the low-temperature performance increased while the high-temperature performance was adversely affected by the increase in the content of the regenerants. The VR and J3.2 of the regenerated AMB were comparable to those of unaged state, when the contents of the rejuvenator and UMB in the aged binder were 5% and 70%, respectively. It indicated that the high-temperature creep and low-temperature relaxation performance of the AMB reach a balance.

Experimental investigation of nano materials applicability in Hot Mix Asphalt (HMA)

• The efficacy of using Nano materials in Hot Mix Asphalt (HMA) was examined. • The effect of CNT and NC, loading frequency and temperature on dynamic modulus and resilient modulus were investigated. • Nano materials (CNT and NC) led to higher stiffness improved Dynamic stability rutting resistance and moisture resistance of HMA. • The optimized percentage of CNT and 1.5% CNT with NC in HMA was determined to be 1.5% and 6%, respectively. • MEP and regression techniques was developed in predicting the dynamic modulus of the nano material modified HMA. Nanotechnology for asphalt modification and incorporating nanomaterials into Hot Mix Asphalt (HMA) to deal with road failure have gained popularity recently. Researchers have reported the improved performance of asphalt modified by nanomaterials but most of the study is limited to binder modification using nanomaterials. The utilization of Nanomaterials in HMA can significantly improve the performance indicators in the form of extension in pavement service life and decrease pavement distresses. The Nanomaterials reinforcement of HMA can enhance pavement performance indicators, including low and high-temperature dynamic modulus and stability and enhancement in rut resistance and stiffness modulus. Nano Materials modified is a suitable solution to improve the mechanical properties of HMA. The current study objectives focus on the experimental investigation of Nano Materials such as Carbon Nano Tubes (CNT) and Nano Clay (NC) applicability in HMA. CNT and NC percentages used in HMA to the weight of bitumen are 0.5%, 1.5%, 2.5% and 2%, 4%, 6%, 8%. Conventional and Nanomaterial modified asphalt mixes were subjected to performance tests such as Simple Performance Tester (SPT), Dynamic Stability and Rutting, Tensile Strength Ratio (TSR), and Resilient Modulus ( M R ) using UTM-25. The present study further aimed to predicting dynamic modulus of nanomaterial modified HMA through Artificial intelligence (AI) modeling using Multi Expression Programming (MEPX) and Regression modelling with validation. Results have indicated that the addition of CNT and NC has improved HMA properties such as enhancement in dynamic modulus and dynamic stability and improves stiffness, rut resistance, and moisture resistance. It has been observed that 1.5% CNT with 6% NC content by weight of bitumen in asphalt mixtures outperformed other CNT and NC percentages. Moreover, Dynamic stability and Rut resistance have been improved by 820% and 64.7%, respectively, while resilient modulus increased by 309% and moisture susceptibility has been reduced by 22.26%. Overall, the asphalt mixtures with 1.5% CNT with 6% NC content has the best results.

Short-term aging characteristics and mechanisms of SBS-modified bio-asphalt binder considering time-dependent effect

• Short-term aging mechanisms of the SBAs considering time-dependent effect. • Effects of aging time on the ageing mechanisms of the SBAs. • Effects of bio-asphalt content on the aging mechanisms of the SBAs. Bio-asphalt has emerged as a reliable material for replacing conventional asphalt in asphalt modification owing to its well social, environmental and economic benefits. However, the short-term aging mechanisms of modified bio-asphalt binders considering time-dependent effect have not been discussed widely in previous studies. In this study, considering the extensive use of SBS-modified bio-asphalt binders, the aging characteristics of an SBS-modified bio-asphalt binder (SBA) based on six different aging times (0 min, 40 min, 65 min, 130 min, 195 min, and 260 min) and four different bio-asphalt contents (0%, 3%, 6%, and 9%) are investigated using the rolling thin film oven test (RTFOT). Bio-asphalt can significantly improve the aging resistance of the SBA, although the improvement effect decreases as the bio-asphalt content increases. Moreover, the short-term aging mechanisms of the SBA considering time-dependent effect are determined based on fluorescence microscope (FM) and Fourier transform infrared spectroscopy (FTIR). The results indicate that the aging of the SBA at early stage is primarily attributed to the disintegration of the SBS cross-linked structure due to the volatilization of light components (e.g., saturates and aromatics) and the thermal-oxidative degradation of styrene-butadiene. With the increase of aging time, aging is primarily caused by the conversion of resins, saturates, and aromatics to asphaltenes due to the oxidation of the polyunsaturated carbon chain and sulfur. Although bio-asphalt can delay the aging, it does not change the evolution process.

Effect of water immersion on the AC-WC mixture utilizing elastomeric modified asphalt to compressive strength, elastic modulus and durability

Indonesia has relatively high rainfall with a long duration of rain. It can result in a flood on the surface of the road. A flood can reduce the strength of materials from the asphalt mixture and cut the life of the road plan. Therefore, it is necessary to conduct a study that can measure the durability level of the asphalt material mixture on the surface layer of the road to the flood water bath. The study used an Asphalt Concrete-Wearing Course (AC-WC) mixture with Elastomeric Modified Asphalt (EMA), and an Upper Limit (UL), Middle Range (MR), and Lower Limit (LL) gradation based on specification. The Optimum Bitumen Content (OBC) value was obtained from each gradation by applying the Marshall test. The value of the OBC was used to create specimens that had a diameter of 3 inches and a height of 6 inches, and they were using an Unconfined Compression Strength (UCS) test. This study measures the durability of compressive strength and elastic modulus from a mixture of flood water immersion for 1, 2, 4, and 7 days. To calculate the durability using Retained Strength Index (RSI), First Durability Index (r), and Second Durability Index (a). The results showed that there was a decrease in the compressive strength of the mixture on gradations of UL, MR, and LL on days 1, 2, 4, and 7. It meant that the longer the immersion time more reduced the compressive strength of the mixture. The UL-gradedraded mixture had the best durability when it was compared to the MR and LL gradations up to the 7th-day immersion, with an RSI of 91.19%, (r) of 7.44%, and (a) of 6.93%. At the same time, in the elastic modulus of the mixture, there was no significant effect on the duration of immersion because it had a fluctuating value of the elastic modulus to the duration of immersion.

Thermal storage properties of polyurethane solid-solid phase-change material with low phase-change temperature and its effects on performance of asphalt binders

Preparing phase change materials (PCMs) with appropriate phase-change temperatures is of great significance in preventing the low-temperature disease in pavements. In this study, several polyurethane solid-solid PCM (PUPCM) samples were prepared via a two-step condensation reaction of polyethylene glycol, polytetramethylene ether glycol, 4,4′-diphenyl methane diisocyanate, and 4,4′-methylenebis-(2-chloroaniline). Considering the phase-change temperature and thermal stability, a PUPCM sample with a suitable molar ratio was used for the asphalt modification. The prepared materials were characterised by Fourier transform infrared spectroscopy, thermogravimetric analysis, differential scanning calorimetry, three indices of asphalt and viscosity tests, rotational viscometer tests, and other techniques. PUPCM samples with different soft and hard segment ratios exhibit different phase-change temperatures and enthalpies, and their physical, chemical, and phase-change properties are stable. When the ratio of soft and hard segments is 8:2 (PU-14), the freezing and melting temperatures were −2.7 °C and 12.9 °C, and the enthalpy was 46.8 J/g. The PUPCM modification of asphalt only involves physical miscibility. Adding PUPCM negligibly affects the high- and low-temperature performances of the modified asphalt binder. The viscosity of the PUPCM-modified asphalt binder is slightly higher than that of the original asphalt binder, and the storage stability of the modified asphalt binder is satisfactory. The addition of PUPCM improves the anti-ageing performance of asphalt, and the improvement becomes significant with increasing PUPCM content. Moreover, the phase-change energy storage properties of PUPCM in asphalt were found to be satisfactory. Hence, PUPCMs can potentially be used for asphalt modification to further improve the low-temperature performance of pavements.

Enhancement of the Rutting Resistance of Asphalt Mixtures at Different High Temperatures Using Waste Polyethylene Polymer

The temperature and stress caused by the load can be cited as two main parameters leading to breakage in asphalt pavement, especially rutting (permanent deformation). So, to reduce the problems of rutting of roads, several actions have been taken, including improving pavement quality and the structure design methods. The increase in the attention of respective engineers in the last few years to modify and improve the asphalt performance through providing different types of additives and replacing the raw materials of asphalt mixture with recycled materials to improve the environment and reduce the cost of modified pavement mixture. This study discussed the use of low-density waste polyethylene as an asphalt modifier in percentages of (2, 4, and 6) % by the weight of asphalt and their impact on the performance of asphalt mixtures at high temperatures. This study showed that using plastic waste (low-density polyethylene) as a bitumen modifier improved the performance of asphalt mixtures at different high temperatures. This was achieved by reducing the rut depth by (80.5) % and (82.3) % at temperatures of 50 C and 60 C, respectively, using low-density polyethylene waste at an optimum value of about 4% by weight of asphalt in addition to enhancing the Marshall stability by using this percentage of polymer.

A comprehensive evaluation of mixture and binder properties to explore the use of low-density polyethylene (LDPE) as an asphalt modifier and co-modifier

ABSTRACT There has been growing interest in the use of polyethylene (PE) in the asphalt industry as one way to mitigate the adverse environmental impact of waste plastics. The main goal of this study was to evaluate the potential use of low-density polyethylene (LDPE) as a modifier for use in asphalt mixtures. In addition, this study also explored the potential synergistic impact of using elastomeric polymers typically used with asphalt binders as a co-modifier along with LDPE. This study was based on a comprehensive evaluation of the rheological and performance-related properties of asphalt binder from two very different sources as well as asphalt mixtures produced using a subset of these binders. Typical methods that are standard practice in the industry and methods that are being developed to evaluate the performance metrics of asphalt binders and mixtures were used. The two chemically diverse base binders and redundancy in the evaluation process were introduced to ensure a more robust evaluation of the expected properties. Overall, results demonstrate that although the impact of LDPE on the expected performance of the binder may vary with the source of binder, LDPE can be successfully used to enhance the properties of the asphalt binder in most respects, particularly with the synergistic use of a conventional elastomeric modifier.

Bio-grafted silica to make an asphalt road a sink for reactive environmental pollutants

Asphalt-surfaced areas such as roads have been reported as major non-combustion sources of reactive organic compounds in urban areas. Emission of latter compounds from asphalt is exacerbated due to exposure to sunlight and high temperature, contributing to negative human and environmental health outcomes. Furthermore, loss of asphalt components over time is linked to bitumen's aging that reduces service life of roads. Here, we introduce a designed bio-grafted-silica nano-filler derived from wood pellet as a sink for latter volatile compounds in an asphalt mixture. Molecular modeling calculations showed the remarkable adsorptive activity of the bio-grafted silica for trapping select asphalt volatiles, especially for the sulfur-containing aromatics and the oxygen-containing aromatics. Laboratory experiment revealed that the bitumen modified with bio-grafted silica exhibited up to 23% lower signs of aging. Thermogravimetric analysis proved that the modified bitumen exhibited a 16% reduction in mass loss compared to neat bitumen. Dynamic vapor sorption analysis also showed bio-grafted silica adsorbed higher amounts of a candidate volatile than pristine silica. The study outcomes highlights the advantages of a bio-derived modifier in asphalt to address concerns associated with the loss of hazardous compounds.

Property Characterization of Anti-Aging Additives and Modified Asphalt Based on Long-Term Aging Behavior

In order to achieve the good application of hindered amine light stabilizer (HALS) in the long-term aging control of asphalt pavement material, Tinuvin770 and Tinuvin622 light stabilizers were selected as modifiers for asphalt. The microstructure and characteristics of hindered amine light stabilizers were characterized by FIB-SEM. The elemental composition and relative content of hindered amine light stabilizers were studied by means of EDS analysis. The functional group composition of hindered amine light stabilizers was analyzed based on Dynamic-FTIR. On this basis, light stabilizer modified asphalt was prepared, and the effect of hindered amine light stabilizer on the thermal rheological properties of asphalt binder during UV aging period was studied by dynamic shear rheology (DSR). The changing law of low temperature rheological properties of hindered amine light stabilizer modified asphalt was evaluated by low temperature bending beam rheological test (BBR). The results showed that the hindered amine light stabilizer could capture the free radicals formed during the photodegradation of asphalt when subjected to ultraviolet aging. Under the impact of ultraviolet aging, hindered amine light stabilizer could improve the high temperature performance of asphalt binder. Furthermore, HALS could achieve the improving effect on the low temperature rheological properties and long-term aging performance of asphalt pavement materials.

Study on Rheological Properties of Graphene Oxide/Rubber Crowd Composite-Modified Asphalt.

In order to improve the durability of asphalt pavement and prolong the service life of heavy traffic asphalt pavement, graphene oxide (GO) and rubber powder (RP) were used as composite modifiers to modify matrix asphalt. The high-temperature rheological properties of composite-modified asphalt at different temperatures and frequencies were analyzed. The influence of different stress levels on the viscoelastic properties of composite-modified asphalt was evaluated. The low-temperature rheological properties of composite-modified asphalt were studied. The difference between RP-modified asphalt and GO/RP composite-modified asphalt was analyzed, and the mechanism of GO and RP on asphalt modification was explored. The results show that the composite-modified asphalt has good rheological properties at low temperature, relatively smooth surface and stable network structure, which improves the segregation problem of RP in matrix asphalt. At present, GO and RP are rarely used as composite modifiers to modify matrix asphalt at home and abroad, which is an innovation in material selection.

Adhesion Characterization of Palm Oil Mill Sludge Modified Asphalt Binder

The adhesion of mineral aggregates to asphalt binder is an essential point that attributes to the quality and performance of the asphalt mixture. Moreover, the considerable problem to the asphalt pavement could come from the lack of bonding between the materials. Generally, adhesion of mineral aggregates depends on the source or type of aggregate and asphalt binder. This study investigated the adherence coverage of palm oil mill sludge (POMS) modified binder with granite aggregate. Base asphalt binder of penetration grade 60/70 was blended with 1%,2%,3%,4% and 5% of POMS to produce the modified asphalt binders, respectively. Consequently, POMS modified binders were mixed with the granite aggregate to produce loose mix samples. In this current study, boiling test procedure was used to reduce the adhesive bonding of the loose mix sample. Then, Image J software was used to evaluate the stripping area of the samples. The results from image analysis revealed that different stripping areas due to different amounts of POMS incorporated in the modified asphalt binder. Up to 4% POMS modified asphalt showed an acceptable resistance toward moisture compared to un-modified asphalt. Image J helped to produce a clear stripping result compared to visual observation. In conclusion, POMS could be used as an asphalt modifier with satisfactory adhesion properties.