Effect of Graphene Oxide on the Low-Temperature Crack Resistance of Polyurethane–SBS-Modified Asphalt and Asphalt Mixtures

Durability Investigation of Ultra-Thin Polyurethane Wearing Course for Asphalt Pavement

In this study, a wear-resistant ultra-thin wear layer was fabricated with polyurethane as an adhesive to investigate its durability for pavement applications. Its road performance was investigated based on indoor tests. First, the abrasion test was performed using a tire-pavement dynamic friction analyzer (TDFA), and the surface elevation information of the wear layer was obtained by laser profile scanning. The relationship between the anti-skid properties of the wear layer and the macro-texture was analyzed. Second, a Fourier infrared spectrometer and scanning electron microscope were employed to analyze the evolution of polyurethane aging properties in the pull-out test and accelerated ultraviolet (UV) aging test. The results showed that the mean profile depth (MPD), arithmetic mean wavelength of contour (λa), surface wear index (SBI), stage mass loss rate (σ), and total stage mass loss rate (ω) of the abrasive layer aggregate had significant multivariate quadratic polynomial relationships with the skidding performance of the abrasive layer. The tensile strength of the polyurethane ultra-thin abrasive layer decreased by only 2.59% after 16 days of UV aging, indicating a minimal effect of UV action on the aggregate and structural spalling of the polyurethane abrasive layer.

The Effects of Aging on Microstructures and Rheological Properties of Modified Asphalt with GO/SBS Composite

This work aimed to investigate the effects of aging on the microstructures and rheological properties of modified asphalt with a GO/SBS composite, since the styrene-butadiene-styrene block copolymer is potentially compatible with graphene oxide (GO). The GO/SBS composites, which were used as a kind of modifier, were prepared via the solution-blending method. GO/SBS composites with varying GO contents were employed to prepare the GO/SBS-compound-modified asphalt (GO/SBS-MA). Then, the GO/SBS-MA underwent PAV (pressure aging vessel) or UV (ultraviolet) aging tests to simulate different aging circumstances. The microstructures of the asphalt binders were studied using FTIR (Fourier-transform infrared spectroscopy) and AFM (atomic force microscope) tests. Moreover, DSR (dynamic shear rheometer) and BBR (bending beam rheometer) experiments were carried out to investigate the rheological properties of the GO/SBS-MA. The results showed that the addition of GO improved the high-temperature stability of the asphalt binder while slightly impairing its performance at low temperatures. GO restrained the formation of carbonyl and sulfoxide groups as well as the breakdown of C=C bonds in the polybutadiene (PB) segment, promoting the anti-aging performance of GO/SBS-MA. Furthermore, the interactions between the GO/SBS and the asphalt binder resulted in the formation of needle-like aggregates, enhancing the stability of the asphalt binder. The asphalt binders with a higher content of graphene oxide (GO) exhibited not only a better high-temperature performance, but also a better aging resistance. It was concluded that the macroscopic properties and microstructures were significantly affected by GO, and a moderate increase in the amount of GO could contribute to a better aging resistance for GO/SBS-MA.

Synthesising graphene from plastic waste and its use with asphalt

The global increase in the plastic waste has resulted in significant pollution increase which causes significant damage to the environment. There is an urgent need for waste management practices such as recycling to ensure sustainable development and decreasing the impact of plastic waste on the environment. The production of new materials such as graphene are associated with high cost, and there have been research efforts to develop cost effective alternative sources of graphite. considerable research has been carried out on investigating the application of homo polypropylene in asphalt construction. successful applications of this will ensure recycling and reduce waste footprint of plastic. The paper presents a proposed method of synthesising graphene from plastic waste and talc at 80 %, and 20 % of that after many experiments. Graphene was monitored at (002). (100). (004) peaks at 2 θ = 26.8°, 42°, with 53 successive physical tests conducted to determine the quality of the graphene produced. The experiments carried out resulted in a successful production of a 98 % pure material. The synthesised graphene was then combined with asphalt using different ratios of weight: 2 %, 6 %, 8 %, and 10 % to test the physical properties of the combination. The results were compared with no graphene usage, the findings validated the findings of similar studies which demonstrate at 6 % ration combination with graphene the asphalt provides better results than without graphene. Also, testing at alternative forces of 6.5 psi and 13 psi at temperatures of 25, 40 and 60, the results showed a noticeable improvement. All tests showed better results in creep and tensile strength. It is concluded that there is a proofed concept to follow this approach to recycle waste plastic in ample ways to reduce the footprint of waste.

Properties and Characterization Techniques of Graphene Modified Asphalt Binders

Graphene is a carbon-based nanomaterial used in various industries to improve the performance of hundreds of materials. For instance, graphene-like materials have been employed as asphalt binder modifying agents in pavement engineering. In the literature, it has been reported that (in comparison to an unmodified binder) the Graphene Modified Asphalt Binders (GMABs) exhibit an enhanced performance grade, a lower thermal susceptibility, a higher fatigue life, and a decreased accumulation of permanent deformations. Nonetheless, although GMABs stand out significantly from traditional alternatives, there is still no consensus on their behavior regarding chemical, rheological, microstructural, morphological, thermogravimetric, and surface topography properties. Therefore, this research conducted a literature review on the properties and advanced characterization techniques of GMABs. Thus, the laboratory protocols covered by this manuscript are atomic force microscopy, differential scanning calorimetry, dynamic shear rheometer, elemental analysis, Fourier transform infrared spectroscopy, Raman spectroscopy, scanning electron microscopy, thermogravimetric analysis, X-ray diffraction, and X-ray photoelectron spectroscopy. Consequently, the main contribution of this investigation to the state-of-the-art is the identification of the prominent trends and gaps in the current state of knowledge.

A Multistage Analysis of Asphalt Binder Nanocrack Generation and Self-Healing Behavior Based on Molecular Dynamics

In order to study the characteristics and laws of nanocrack generation and self-healing behavior of asphalt materials under tensile action, the molecular dynamics (MD) method was used to simulate the continuous “tensile failure—self-healing” process, and this study remedies the shortcomings of existing experimental and observational methods. It is found that the MD-reproduced formation process of asphalt binder nanocrack contains four stages: “tensile extension”, “nanocrack generation”, “crack adding, expanding and penetrating” and “cracking failure”. The influence of tensile conditions on the tensile cracking simulation of an asphalt binder model was analyzed, and it was found that low temperature and high loading rate would increase the tensile strength of the asphalt binder model. In addition, the MD-reproduced healing process of asphalt binder nanocracks can be divided into four stages: “surface approach”, “surface rearrangement”, “surface wetting” and “diffusion”, which is similar to the healing process of polymers. Finally, from the perspective of energy change, the change rule of dominant van der Waals energy in the self-healing process was studied. Based on the existing research, the influence of damage degree on the healing performance of asphalt binder and its mechanism were further analyzed. The research results further enrich the theoretical research on microlevel cracking and healing of asphalt materials, and have certain theoretical value for the further development of self-healing asphalt materials.

Effect of Graphene Oxide on Aging Properties of Polyurethane-SBS Modified Asphalt and Asphalt Mixture

In order to clarify the effect of the new nano-material graphene oxide on the performance of Polyurethane-SBS modified asphalt and asphalt mixture under the effect of thermal aging, the cracking process of semicircular bending test (SCB) specimens was monitored in situ based on computer vision image processing technology (OpenCV), and the modified asphalt and the cracking characteristics of the modified asphalt and mixture were further analyzed by the tests of semicircular three-point bending and aggregate contact angle measurement. The test results showed that the thermal aging effect severely damaged the composite structure formed by the cross-linking effect of Polyurethane and SBS modifier in asphalt, which intensified the degradation of Polyurethane and SBS modifier and led to great changes in the rheological properties of asphalt after aging. However, the incorporation of the new nanomaterial Graphene oxide can slow down the degradation of Polyurethane and SBS modifiers and the change of asphalt cross-linked composite structure, making the anti-cracking and anti-aging properties of Graphene oxide-Polyurethane-SBS modified asphalt mixes better than those of Polyurethane-SBS modified asphalt mixes. Therefore, the new nano-material graphene oxide added to Polyurethane-SBS modified asphalt is meaningful and feasible. Graphene oxide-polyurethane-sbs composite modified asphalt, as a new nano-material modified asphalt, is stronger against the ultraviolet and light asphalt that is prone to aging. With regards to improving the application of road projects, the results are very promising.

Grey Correlation Analysis of Physical Properties and Evaluation Index of Graphene-Oxide-Modified Asphalt

The purpose of this study is to analyze the behavior of the performance index of graphene-oxide-modified asphalt. The deviation problem caused by determining graphene oxide content by single performance or several independent properties is also investigated. By testing the physical properties of graphene-oxide-modified asphalt with different admixtures (0%, 0.5%, 1.0%, 1.5%, 2.0% by mass) in terms of viscosity, penetration, softening point, ductility, rheology, etc., it is concluded that the addition of graphene oxide could improve the individual properties of the matrix asphalt by 3% to 250%. Moreover, the grey correlation analysis method is used to calculate and analyze the correlation between the performance of graphene-oxide-modified asphalt and the content of graphene oxide. The latter has the most significant effect on the softening point, the penetration, and the 135 °C Brookfield viscosity of modified asphalt. The content of graphene oxide in graphene-oxide-modified asphalt is calculated based on the above three performance indexes, and an estimation error of less than 0.15% is observed. This proves that the new determination method is reasonable. Finally, by combining the macroscopic properties and the multi-factor statistical analysis, a reference basis is provided for the quality control of the graphene-oxide-modified asphalt.

Effect of Polyurethane on High- and Low-Temperature Performance of Graphene Oxide-Modified Asphalt and Analysis of the Mechanism Based on Infrared Spectrum

This study aims to analyze the effect of polyurethane (PU) on the high- and low-temperature performance of graphene oxide (GO)-modified asphalt. Using the three major-indices tests, bending beam rheometer (BBR) test and dynamic shear rheometer (DSR) test, the results show that composite modified asphalt improved each performance by 10% to 140% compared to the base asphalt. The change in functional groups of the composite-modified asphalt is detected by infrared spectrum scanning to analyze the modification mechanism. The asphalt preference system is established using analytic hierarchy process (AHP) in the cold region of northeastern China and the SA index is creatively added to the system to make the analysis results more accurate, resulting in 0.5% GO/4% PU being determined as the best content. This study overcomes the limitation that GO-modified asphalt cannot be used in cold areas due to its low-temperature performance, and it can be widely used as a new composite material with its high performance.