Chapter 14 Chemical Composition of Asphalt as Related to Asphalt Durability

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.

Effect of Graphene Oxide on Liquid Water-Based Waterproofing Bituminous Membranes

In this work, innovative graphene oxide-doped waterproofing bituminous membranes, also called roof bituminous membranes, were prepared and characterized in terms of physicochemical and vapor transport properties. The results showed that the introduction of a small amount of GO increased the mechanical resistance of the doped membranes compared to the native one. Moreover, the addition of the GO leads to a remarkable chemical stability of the membranes when exposed to UV radiation and high temperatures. Furthermore, a decrease in water vapor permeation was observed when GO was present in the membrane matrix compared to native bituminous membranes, demonstrating that an addition of GO can boost the waterproofing properties of these bituminous membranes.

Waste Polymer and Lubricating Oil Used as Asphalt Rheological Modifiers

The hazards of plastic waste (PW) from polymers (e.g., polyethylene terephthalate (PET), high-density polyethylene (HDPE), low-density polyethylene (LDPE), polyvinyl chloride (PVC), nylon, polystyrene (PS), etc.), the mechanism of its spread in general, and its ubiquity in our daily lives as a continuously and/or frequently expelled product are a crisis of the twenty-first century, as reported by the United Nations in 2019, especially after the outbreak of the COVID-19 pandemic. This research included the process of modifying the rheological properties of asphalt to obtain asphalt suitable for use in a high-humidity atmosphere. The Iraqi climate is characterized by heat that reaches the point of harshness in the summer and coldness that falls below zero on some winter days. From this point of view, our recent study focuses mainly on making rheological and chemical modifications to asphalt using spent polymeric materials and used lubricating oils (ULO), thus achieving two important goals, namely obtaining asphalt with rheological properties resistant to the Iraqi atmosphere as well as eliminating both solid and liquid environmental pollutants. The microstructure and morphology of the designed patches were characterized using scanning electron microscopy (SEM) to indicate phase composition.

Correlation Analysis between Mechanical Properties and Fractions Composition of Oil-Rejuvenated Asphalt

To clarify the intrinsic relationship between the mechanical properties of asphalt and its fraction composition, the SARA fraction composition and six macroscopic mechanical properties (critical cracking temperature (TCR), fatigue life (Nf), non-recoverable creep (Jnr3.2), penetration, ductility, and softening point) were investigated for 16 asphalt samples. Fraction contents of asphaltene and aromatic are strongly correlated with TCR and ductility (R2 > 0.92) that characterize the ability of asphalt to adapt to deformation at low and medium temperatures. Heavy fraction (asphaltene and resins) content is also strongly correlated with (R2 > 0.90) penetration and Jnr3.2 that characterize the resistance of the asphalt to overall deformation at medium and high temperatures. To express the changes in the four fractions simultaneously with one indicator, a statistic, average deviation of the fractions between the given asphalt and its original (marked σ), is introduced in this study to characterize the degree of asphalt aging based on the fraction changes. It normalizes the four simultaneous change indicators (percentage of SARA fractions) during asphalt aging into one indicator. This new indicator has a strong correlation with several mechanical performance indicators of asphalt, where it is strongly correlated with TCR (R2 > 0.90), ductility, and penetration, which are also well correlated with Jnr3.2 (R2 > 0.85), Nf (R2 > 0.75), and softening point (R2 > 0.75).

How Organic Waste Improves Bitumen’s Characteristics

The organic fraction derived from the differentiated collection of urban waste is mainly composed of fatty acids, medium molecular weight hydrocarbons and cellulose. This peculiar composition gave us insight into the possible use of organic waste to improve bitumen’s characteristics (possible antioxidant, regenerating and/ or viscosifying additive for road pavements). The issue of the disposal of organic waste is a global one and it’s constantly of increasing concern. This study looks to alleviate this problem by finding ways for this waste fraction to be utilized for the greater good- in this case, as an additive for bitumen binder in road pavements. The present study is focused on the use of waste as it is and waste treated by the FENTON process (treatment with ferrous sulphate and hydrogen peroxide solution). Dynamic Shear Rheology (DSR) and aging tests (Rolling Thin Film Oven Test, RTFOT) showed that two of the additives tested in this study proved effective: one can be utilised as a viscosifying agent and the other can be us ed as a filler.

Effect of Thermal and Oxidative Aging on Asphalt Binders Rheology and Chemical Composition

Aging of asphalt binders is one of the main causes of its hardening, which negatively affects the cracking and fatigue resistance of asphalt binders. Understanding asphalt aging is crucial to improve the durability of asphalt pavements. In this regard, this study aims at understanding and differentiating the effect of temperature and oxygen uptake on the aging mechanisms of unmodified asphalt binders. For that, four laboratory aging procedures were employed. The two standardized procedures, rolling thin-film oven test (RTFOT) and pressure aging vessel (PAV), were considered to simulate the short-term and long-term aging of the asphalt binders, respectively. In addition, two thin-film aging test procedures, the nitrogen atmosphere oven aging test (NAAT) and ambient atmosphere oven aging test (OAAT) were employed to assess the effect of thermal and oxidative aging on unmodified asphalt binder properties. The NAAT procedure is based on the principle that the inert gas minimizes the oxidative aging. The rheological and chemical characterization showed that the high temperatures considered during the NAAT procedure did not change the properties of the unmodified asphalt binders. Therefore, it can be hypothesized that no significant thermal and oxidative aging was observed during NAAT aging procedure for the considered binders and that oxidative aging is the main cause for the hardening.

Influence of the Long-Term Oven Aging on the Performance of the Reinforced Asphalt Mixtures

The long-term aging of the asphalt mixtures has become a major concern because it decreases the lifespan of the asphalt layer. In this study, the asphalt mixtures incorporating steel slag aggregates were reinforced with synthetic fibers as a novel contribution in terms of decreasing the effect of aging on the performance of the asphalt mixtures. However, different mixtures—namely, Mix0, Mix1, and Mix2—were subjected to long-term oven aging to study the effect of the aging on the performance of the asphalt mixes. Mix0 consisted of coarse and fine granite aggregates, while Mix1 was composed of coarse steel slag aggregate and fine granite aggregate. Mix2 represents the reinforced asphalt mixtures incorporating coarse steel slag aggregate and reinforced with the synthetic fibers of polyvinyl alcohol, acrylic, and polyester at the proportion of 0.3% by weight of the aggregates. The conducted performance tests were resilient modulus, rutting depth, and cracking resistance. The outputs of the performance tests for the unaged asphalt mixes displayed that the mixtures incorporating coarse steel slag aggregate exhibited better performance than the mixtures containing granite aggregate. Meanwhile, the reinforced asphalt mixtures have shown a lower resilient modulus and a higher permanent deformation than the unreinforced asphalt mixes due to the elastic behavior. Otherwise, the reinforced asphalt mixtures have shown superior resistance to cracking in comparison to the unreinforced mixtures. On the other hand, the performance of the aged asphalt mixtures demonstrated that the mixtures containing granite aggregates exhibited a lower susceptibility to aging than the mixtures incorporating steel slag aggregate. Meanwhile, the performance of the aged reinforced asphalt mixtures showed that introducing synthetic fibers has decreased the effect of the long-term oven aging.

Influence of Short-Term Aging on Mechanical Properties and Morphology of Polymer-Modified Bitumen with Recycled Plastics from Waste Materials

Polymer-modified bitumen (PMB) is bitumen that has been specifically engineered with polymer for providing enhanced performance in service. The aging of bitumen is a main aspect that is able to affect its final performance: during the production phase in a hot mix plant, all the binders experience short-term aging due to the high processing temperature. The same is true during the production of the modified binder, when the polymer is dispersed at high temperature in the bitumen mass. This paper aims at studying the effect of short-term aging when using different types of modifiers such as recycled polymers obtained from waste materials. A 50/70 penetration-grade bitumen has been modified, and bitumen characterization has been carried out before and after short-term aging; conventional tests, viscosity measurements, and dynamical mechanical analysis have been used to investigate the properties. Different aging indices have been determined for predicting the effect of short-term aging based on the type of modifier. Furthermore, the morphology of the modified bitumen has been investigated via fluorescent microscopy, before and after aging, in order to highlight morphological changes due to aging. The results confirm that aging affects all the modified binders, due to the thermal stress imposed during PMBs production. Nevertheless, polymer modification is proved to reduce the aging effect in terms of an increase in the elastic modulus as experienced by the original binder.