Rheological Evaluation of Foamed WMA Modified with Nano Hydrated Lime

Although the Warm Mix Asphalt (WMA) is gaining popularity very rapidly and becoming a mainstream technique for producing asphalt mixtures, there are many concerns regarding its long-term performance. Over the years, the Regular Hydrated Lime (RHL) has gained considerable recognition as a common additive to bituminous pavements. However, the Nano Hydrated Lime (NHL) (particle sizes 100 nanometer (nm) or less) has not been used as an additive to the asphalt mixtures before. The rheology properties of foamed WMA were studied since the pavement performance is primarily controlled by the rheological properties of asphalt cement. NHL materials with particle sizes of 50 nm and 100 nm were used in this study along with RHL to investigate the effectiveness of the new generation fabricated NHL modification on the rheological properties of the foamed WMA. NHL was added to the asphalt binder at ratios of 20%, 10%, and 5% (by weight). The foamed WMA was produced by adding Advera® at ratios of 3%, 4.5%, and 6% (by weight). The Dynamic Shear Rheometer (DSR) test was used to evaluate the rutting and fatigue cracking of the binders while the Bending Beam Rheometer (BBR) test was used to evaluate thermal cracking of the binders. The overall results reveal that the binder rheological properties can be enhanced successfully by adding small amounts of NHL. The NHL particle size affects the rheological properties of the binders. The application of the RHL with the normal dose (20% by weight of binder) can be replaced by adding almost 5% (by weight) of NHL (50 nm). The outputs of this study can be interesting from a practical point of view since it was proved that the NHL has interesting functionality on the rheological performance of the binders

Rheological Evaluation of Foamed WMA Modified with Nano Hydrated Lime

Although the Warm Mix Asphalt (WMA) is gaining popularity very rapidly and becoming a mainstream technique for producing asphalt mixtures, there are many concerns regarding its long-term performance. Over the years, the Regular Hydrated Lime (RHL) has gained considerable recognition as a common additive to bituminous pavements. However, the Nano Hydrated Lime (NHL) (particle sizes 100 nanometer (nm) or less) has not been used as an additive to the asphalt mixtures before. The rheology properties of foamed WMA were studied since the pavement performance is primarily controlled by the rheological properties of asphalt cement. NHL materials with particle sizes of 50 nm and 100 nm were used in this study along with RHL to investigate the effectiveness of the new generation fabricated NHL modification on the rheological properties of the foamed WMA. NHL was added to the asphalt binder at ratios of 20%, 10%, and 5% (by weight). The foamed WMA was produced by adding Advera® at ratios of 3%, 4.5%, and 6% (by weight). The Dynamic Shear Rheometer (DSR) test was used to evaluate the rutting and fatigue cracking of the binders while the Bending Beam Rheometer (BBR) test was used to evaluate thermal cracking of the binders. The overall results reveal that the binder rheological properties can be enhanced successfully by adding small amounts of NHL. The NHL particle size affects the rheological properties of the binders. The application of the RHL with the normal dose (20% by weight of binder) can be replaced by adding almost 5% (by weight) of NHL (50 nm). The outputs of this study can be interesting from a practical point of view since it was proved that the NHL has interesting functionality on the rheological performance of the binders

Achievements and prospects of advanced pavement materials technologies

Road transportation is a basic need for mobility and daily life [...

Three-dimensional modeling and simulation of asphalt concrete mixtures based on X-ray CT microstructure images

Abstract:X-ray CT (computed tomography) was used to scan asphalt mixture specimen to obtain high resolution continuous cross-section images and the meso-structure. According to the theory of three-dimensional (3D) reconstruction, the 3D reconstruction algorithm was investigated in this paper. The key to the reconstruction technique is the acquisition of the voxel positions and the relationship between the pixel element and node. Three-dimensional numerical model of asphalt mixture specimen was created by a self-developed program. A splitting test was conducted to predict the stress distributions of the asphalt mixture and verify the rationality of the 3D model

Advanced Pavement Materials for Sustainable Transportation Infrastructure

Many road managers and stakeholders are looking for more and better options for the construction and maintenance of flexible and rigid pavements. Well-designed strategies for pavement construction and maintenance have attracted the interests of researchers since a large number of existing pavements are facing deterioration all over the world. The selection and engineering properties of paving materials are crucial factors affecting the durability and therefore demanding standards of sustainability of the constructed pavement. Researchers worldwide are putting extensive efforts to develop and promote advanced pavement materials and structures for constructing and maintaining sustainable pavements. Pavement materials that can improve durability, cut costs, reduce depletion of raw materials, and lower environmental impacts are desirable for such purposes. Meanwhile, some new design ideas that differ from traditional pavement structures have shown noticeable benefits in terms of pavement durability or cost. In this regard, exploring the benefits of using advanced materials in flexible and rigid pavements is continuously investigated and has currently gained increasing attention. The articles of this issue cover original research papers that will contribute to the development and implementation of advanced pavement materials for sustainable transportation infrastructure

Performance test on Styrene-Butadiene-Styrene (SBS) modified asphalt based on the different evaluation methods

To uniform the evaluation indicators of Styrene-Butadiene-Styrene (SBS) modified asphalt, the SK70# and SK90# matrix asphalt were modified by different SBS modifier dosage in this study. The test methods in China and Superpave were used to test the performance of each SBS-modified asphalt respectively, from which the appropriate evaluation index of SBS-modified asphalt was determined. The results showed that the addition of SBS modifier improved the high temperature performance and lowered the temperature sensitivity of asphalt binder, while it increased the viscosity of asphalt binder in high temperatures. Due to the variability that appeared in the results of the penetration test by the swelling of SBS-modified asphalt, the penetration test was not recommended to evaluate the performances of SBS-modified asphalt. The softening point of SBS-modified asphalt with the modifier dosages of 4.5%, 5%, 5.5% and 6% increased 5.7%, 12.8%, 22.5% and 26.4% respectively compared to the matrix asphalt for SK70# matrix asphalt, and increased 21.2%, 26.3%, 33.6% and 46.6% respectively compared to the matrix asphalt for SK90# matrix asphalt. The effect of SBS-modifier on the softening point of SK90# matrix asphalt is significantly better than that of SK70# matrix asphalt. The improvement effect of SBS modifier on low temperature performance of matrix asphalt decreased with a decrease in test temperature. When studying the influence of the SBS modifier on the low temperature performance of asphalt binder, it was recommended to use the bending beam rheometer (BBR) test to evaluate the low temperature performance of SBS-modified asphalt

Application of Epoxy-Asphalt Composite in Asphalt Paving Industry: A Review with Emphasis on Physicochemical Properties and Pavement Performances

One of the failure mechanisms associated with asphalt paving layers, especially on steel deck bridges, is large permanent deformation, which adversely affects its long-term performance in service. Thus, epoxy resin was introduced in asphalt paving industry to tackle permanent deformation of asphalt mixtures due to its thermosetting nature. In this review, epoxy resin as a dominant component of the epoxy-asphalt composite system was first considered, followed by a discussion on its curing methods and curing mechanism. Furthermore, the physicochemical property and mechanical performance of epoxy asphalt and epoxy asphalt mixture were thoroughly examined. Crosslink density of epoxy asphalt dictates its viscosity and thus the allowable construction time. Phase separation and dispersion of asphalt particles in the epoxy matrix was observed for epoxy-asphalt composite, and it showed superior elastic behavior and deformation resistance capability when compared with conventional asphalt materials. Furthermore, epoxy asphalt mixture exhibited significantly higher compressive strength, much better rutting resistance, and superior durability and water resistance properties. However, its low-temperature cracking resistance was slightly compromised

Performance test on Styrene-Butadiene-Styrene (SBS) modified asphalt based on the different evaluation methods

To uniform the evaluation indicators of Styrene-Butadiene-Styrene (SBS) modified asphalt, the SK70# and SK90# matrix asphalt were modified by different SBS modifier dosage in this study. The test methods in China and Superpave were used to test the performance of each SBS-modified asphalt respectively, from which the appropriate evaluation index of SBS-modified asphalt was determined. The results showed that the addition of SBS modifier improved the high temperature performance and lowered the temperature sensitivity of asphalt binder, while it increased the viscosity of asphalt binder in high temperatures. Due to the variability that appeared in the results of the penetration test by the swelling of SBS-modified asphalt, the penetration test was not recommended to evaluate the performances of SBS-modified asphalt. The softening point of SBS-modified asphalt with the modifier dosages of 4.5%, 5%, 5.5% and 6% increased 5.7%, 12.8%, 22.5% and 26.4% respectively compared to the matrix asphalt for SK70# matrix asphalt, and increased 21.2%, 26.3%, 33.6% and 46.6% respectively compared to the matrix asphalt for SK90# matrix asphalt. The effect of SBS-modifier on the softening point of SK90# matrix asphalt is significantly better than that of SK70# matrix asphalt. The improvement effect of SBS modifier on low temperature performance of matrix asphalt decreased with a decrease in test temperature. When studying the influence of the SBS modifier on the low temperature performance of asphalt binder, it was recommended to use the bending beam rheometer (BBR) test to evaluate the low temperature performance of SBS-modified asphalt

Experimental assessments of methanol-based foaming agent in latex modified foamed binders and warm asphalt mixtures

Latex is one of the natural rubbers that is used to enhance the performance of asphalt pavement for the last few decades. The presence of latex, which is categorized as an elastomer, helps to improve pavement performance and durability. Conversely, higher viscosity of latex modified asphalt binder increases the production-temperatures of asphalt mixture, thus consuming higher energy during asphalt mixture’s production stage. In this study, the effectiveness of methanol as an energy-efficient foaming agent was assessed to reduce the viscosity and enhance the workability of the modified asphalt binder. The basic and rheological properties of the asphalt binders were determined through multiple laboratory tests including expansion ratio and half-life, rotational viscosity, softening point, torsional recovery, and dynamic shear rheometer. The properties of asphalt mixtures were assessed through the service characteristics, mechanical performance, and moisture resistance criteria. It was found that the presence of latex results in an approximately twofold higher expansion ratio and a lower half-life of the asphalt binder at about the same ratio. Through the rotational viscosity test, the application of methanol into asphalt binder decreased the viscosity and led to better workability, despite the addition of latex as an asphalt modifier. The application of methanol into asphalt binder improved the workability of mixture samples and lowered the compaction energy of the compaction process, which are the crucial criteria for a better mixing and compaction process. Methanol foamed asphalt mixtures with latex show much higher resistance to moisture damage and stiffness than control sample even though they were prepared at a lower temperature

Rheological behavior and sensitivity of wood-derived bio-oil modified asphalt binders

The demand for bituminous materials is continuously growing; crude oil-based asphalt binders are non-renewable, and are facing rapid depletion. With the increase of petroleum-based asphalt prices, seeking an alternative, renewable material such as bio-asphalt has become a hot research topic. However, shortcomings in this research area have been identified, notably concerning the high-temperature performance of bio-asphalt at present. This research aims to comprehensively apply conventional tests to, and study the rheological behavior of, the high-temperature performances of bio-asphalt binders, i.e., by temperature and frequency sweeps, using a dynamic shear rheometer (DSR). It will also assess the chemical functional groups of specimens prepared by different aging conditions. Fifty penetration grade base asphalt binder (50#), bio-oil modified asphalt binders with 0%, 5%, 10%, and 30% bio-oil contents by mass, and bio-oil modified asphalt binder with combinations of 5% bio-oil-1% SBS, and 10% bio-oil-1% SBS were used in this study. The conventional performance of bio-asphalt binders was tested using penetration, ductility, and softening point, before and after short-term aging conditioning. The temperature sweep and frequency sweep of bio-asphalt under different bio-oil contents were carried out via DSR. Two-logarithmic equations of rutting factor and temperature were established, and the temperature sensitivity of bio-asphalt was analyzed. The master curves of virgin asphalt and bio-asphalt were constructed at 64 °C. The results indicate that the incorporation of bio-oil reduced the anti-rutting performance of asphalt, and the bio-oil content had a significant effect on the mass loss of the bio-asphalt binder. The performance of bio-oil modified asphalt binders using 5% bio-oil, 5% bio-oil-1% SBS, and 10% bio-oil-1% SBS, could meet the requirements of 50# grade asphalt. The temperature sensitivity of bio-asphalt did not show obvious change before and after short-term aging, whereas the temperature sensitivity of bio-asphalt with 5% bio-oil was relatively small. With an increase in temperature, the phase angle increased gradually. In contrast, the storage modulus, loss modulus, and complex modulus decreased progressively. The complex modulus and rutting factor of bio-asphalt with 5% bio-oil steadily increased with the increase in testing frequency. Otherwise, chemical reactions were detected in the 50# base asphalt modified with the bio-oil