This study evaluated the aging characteristic of foamed warm mix asphalt (WMA) produced by water injection in comparison to traditional hot mix asphalt (HMA). Four types of asphalt binders (PG 64-22, PG 64-28, PG 70-22, PG 76-22) were used in the preparation of the foamed WMA and HMA mixtures. All mixtures were prepared using limestone aggregates with a nominal maximum aggregate size (NMAS) of 12.5 mm that met the Ohio Department of Transportation (ODOT) Construction and Material Specifications (C&MS) for Item 442 (Superpave Asphalt Concrete).The short-term and long-term aging of the asphalt binders were simulated using the rolling thin film oven (RTFO) and the pressure aging vessel (PAV), respectively, while the short-term and long-term aging of the laboratory-prepared asphalt mixtures were simulated according to AASHTO R 30 (Mixture Conditioning of Hot Mix Asphalt).The dynamic shear rheometer (DSR) was used to characterize the viscoelastic behavior of the unaged, RTFO-aged, and PAV-aged asphalt binders, while the dynamic modulus (lE*l) test was used to characterize the viscoelastic behavior of the short-term and long-term aged foamed WMA and HMA mixtures.In addition, the mechanistic-empirical pavement design guide (MEPDG) global aging model was used to predict the effect of aging on the dynamic modulus (lE*l) of foamed WMA and HMA mixtures, and the MEPDG global aging model predictions were compared to dynamic modulus (lE*l) test results obtained in the laboratory for both asphalt mixtures. By comparing the DSR test results following RTFO and PAV to those obtained for the unaged asphalt binders, it was observed that PG 64-22 was the least susceptible to aging followed by PG 70-22, PG 76-22, and PG 64-28. Similar trends were also observed from the dynamic modulus test, where little difference was noticed between the short-term and long-term aged specimens prepared using PG 64-22 for both foamed WMA and HMA mixtures.The dynamic modulus test results also revealed slightly lower lE*l values for foamed WMA mixtures in comparison to traditional HMA mixtures. This indicates that foamed WMA mixtures are slightly more susceptible to rutting than HMA mixtures. However, by comparing the dynamic modulus of the long-term aged specimens to the short-term aged specimens, it was observed that the increase in stiffness for the foamed WMA mixtures was less than that for the traditional HMA mixtures. This indicates that foamed WMA mixtures are less susceptible to aging and subsequently fatigue cracking than HMA mixtures.Finally, by the comparing the MEPDG global aging model predictions to the dynamic modulus test results for both foamed WMA and HMA mixtures, it was observed that the MEPDG global aging model provided more reasonable predictions, especially at higher frequencies, but overestimated or underestimated the dynamic modulus at lower frequencies. This was observed for both foamed WMA and HMA mixtures, which suggests that this model can be used for both types of mixtures.

In recent years, a group of technologies has been introduced in the United States that allows producing asphalt mixtures at temperatures 30 to 100oF lower than what is used in traditional hot mix asphalt (HMA). This group of technologies is commonly referred to as Warm Mix Asphalt (WMA). From among these technologies, foamed WMA produced by water injection has gained increased attention from the asphalt paving industry in Ohio since it does not require the use of costly additives. This study evaluated the low-temperature performance of foamed WMA and compared it to traditional HMA. Two asphalt binders (PG 70-22 and PG 64-28), two aggregate types (limestone and crushed gravel), and two aggregate gradations (12.5 mm NMAS and 19.0 mm NMAS) were used in this study. The low-temperature behavior of the asphalt mixtures was evaluated using the thermal stress restrained specimen test (TSRST). In addition, the low-temperature properties of the asphalt binders were measured using the bending beam rheometer (BBR). This allowed for comparing the fracture temperature obtained from the TSRST to the low-temperature performance grade obtained using the BBR test.In general, the foamed WMA mixtures exhibited warmer fracture temperatures and lower fracture stresses in the TSRST than the traditional HMA mixtures. This indicates that the HMA mixtures have better resistance to low-temperature cracking. It was found that the binder grade had the most significant effect on the fracture temperature followed by the mix type, while the aggregate type had the most significant effect on the fracture stress followed by the binder grade and the mix type. The fracture temperatures measured in the TSRST were also found to be consistent with the low-temperature performance grades obtained using the BBR test.

This work presents the results of RILEM TC 237-SIB (Testing and characterization of sustainable innovative bituminous materials and systems). The papers have been selected for publication after a rigorous peer review process and will be an invaluable source to outline and clarify the main directions of present and future research and standardization for bituminous materials and pavements. The following topics are covered: - Characterization of binder-aggregate interaction - Innovative testing of bituminous binders, additives and modifiers - Durability and aging of asphalt pavements - Mixture design and compaction analysis - Environmentally sustainable materials and technologies - Advances in laboratory characterization of bituminous materials - Modeling of road materials and pavement performance prediction - Field measurement and in-situ characterization - Innovative materials for reinforcement and interlayer systems - Cracking and damage characterization of asphalt pavements - Recycling and re-use in road pavements This is the proceedings of the RILEM SIB2015 Symposium (Ancona, Italy, October 7-9, 2015).

Over the years, the use of warm mix in pavement structures has continued to gain increasing attention in United States because of its implicit advantages over the traditional hot mix. This has necessitated increased research efforts into understanding different aspects of its behaviour and performance. Aging of asphalt is particularly of much importance because it leads to several problems such as pavement rutting, fatigue cracking and thermal cracking. The aging that occurs during mixing and compaction is commonly referred to as short term aging while the aging that occurs during the pavement service life is called long term aging. The main reason for aging in binders is oxidation and binders become stiffer due to oxidation. Several research projects have been carried out on investigating the aging behavior of warm mix asphalt (WMA) produced by different chemical additives. But no major study has been conducted to understand the aging behavior of foamed WMA. Therefore, this study characterizes the aging behavior of foamed (WMA) as it compares to the traditional hot mix asphalt (HMA) using the Dynamic Shear Rheometer (DSR), Fourier Transforms Infrared Spectroscopy (FTIR), and Gel Permeation Chromatography (GPC) tests. Investigation of the effect of extraction and recovery with trichloroethylene on the stiffness of binders was initially carried out. In addition to preparation of mixtures, aging of binders (RTFO and PAV) and aging of mixtures (STOA and LTOA) being simulated in the laboratory using PG 70-22M and PG 64-22 binder grades, field cores were also obtained from test sections which had been in service for five years. Binders were extracted and recovered from both laboratory and field samples for subsequent physical and chemical tests. These results were analysed and used to evaluate the aging behavior of foamed WMA as it compares to HMA. It was observed that extraction and recovery procedure with trichloroethylene had minimal effect on PG 70-22M binders while it had a reductive effect on rutting and fatigue parameter values of PG 64-22 binders at different levels of aging. Both foamed WMA and HMA for PG 70-22M responded similarly to field and laboratory-simulated aging conditions. But for PG 64-22 binders, foamed WMA was found to be less susceptible to aging than the traditional HMA. Therefore, it implies that when the foamed warm mix technology is used, it may be expected to have a better performance in fatigue cracking but more susceptible to rutting or permanent deformation that takes place in pavement early years when compared to the traditional Hot Mix Asphalt.

Advances in Functional Pavements is a collection of papers presented at the 7th Chinese-European Workshop (CEW) on Functional Pavement (Birmingham, UK, 2-4 July 2023). The focus of the CEW series is on field tests, laboratory test methods and advanced analysis techniques, and covers analysis, material development and production, experimental characterization, design and construction of pavements. The main areas covered by the book include: Green pavements for circular and low-carbon economy Intelligent pavements for future and smart cities Durable pavements for long-life infrastructures Safe pavements for user-friendly build environments Advances in Functional Pavements aims at contributing to the establishment of a new generation of pavement design methodologies in which rational mechanics principles, advanced constitutive models and advanced material characterization techniques shall constitute the backbone of the design process. The book will be much of interest to professionals, academics and practitioners in pavement engineering and related disciplines as it should assist them in providing improved road pavement infrastructure to their stakeholders.

In recent years Warm Mix Asphalt (WMA) technologies have been used to modify asphalt binders, with the following objectives: to decrease production and construction temperatures, reduce fumes and emissions, increase haul distance, and improve the workability of the mix. Reduced temperatures at the plant and during laydown and compaction are hypothesized to positively impact long-term oxidative aging behavior due to less oxidation/aging and result in less emissions during production and construction due to reduced production and construction temperatures. The purpose of this investigation was to quantify these improvements with respect to long-term oxidative aging in the field and environmental benefits with respect to volatile organic compounds, semi-volatile organic compounds and poly cyclic aromatic hydrocarbons in order to confirm or deny this hypothesis. This research evaluated the potential durability of WMA and Rubberized Warm Mix Asphalt (R-WMA) binders with respect to long-term aging through characterization of field-aged binders extracted and recovered from field cores. The results were compared to the control conventional Hot Mix Asphalt (HMA) and Rubberized Hot Mix Asphalt (R-HMA) samples. Binders were extracted and recovered from thirteen different test sections and a total of seven different WMA technologies were evaluated in this study. The Dynamic Shear Rheometer (DSR) was used to evaluate the rheological properties of the binders at high temperatures with respect to rutting performance in the field. The Bending Beam Rheometer (BBR) was used to characterize low temperature properties of the binder samples. A new testing procedure was developed to measure and characterize the rheological properties of the R-HMA and R-WMA binders with respect to performance-related properties in the field. The rheological results indicated that depending on the WMA technology used, the addition of WMA technologies and reduced production and compaction temperatures result in increase or decrease rutting resistance performance for WMA and R-WMA binders with respect to permanent deformation at high temperatures in the field. Both WMA and R-WMA binders studied meet the established thermal cracking criteria with respect to low temperature cracking in the field. The aging kinetics curves for WMA-treated binders are parallel to the control binders and the addition of WMA technologies including organic, chemical and mechanical foaming technologies studied in this research did not result in a different aging kinetics trend with respect to long-term aging in the field. A portable "flux" chamber was designed and fabricated to capture and directly measure emissions during paving operations. Emissions were collected in activated charcoal sorbent tubes for characterizing volatile organic compounds and semi-volatile organic compounds. XAD-2 resin tubes and filters were used to capture the gaseous phase and particulate phase of the PAH compounds, respectively. A reliable analytical method was developed to identify and quantify alkane emissions using gas chromatography mass spectrometry (GC/MS) in the laboratory. A separate method was developed for identification and characterization of trace level PAH compounds of the asphalt fumes. The results demonstrated that the warm mix asphalt technology type, plant mixing temperature and level of compaction significantly influence the emission characteristics throughout paving operations. Moreover, the emissions kinetics indicated that the majority of the reactive organic gases are volatilized in the first hour after sampling initiation (immediately after production and before compaction). To better understand and identify any chemical composition changes of the binder due to WMA technologies, nuclear magnetic resonance spectroscopy (NMR) was used for understanding structural complexities of HMA and WMA binder molecules. Qualitative analysis of both carbon and hydrogen atoms with HMA and WMA binders showed that the molecular structures of the binders are not significantly changed by the effect of WMA technologies.