Re-refined Engine Oil Bottoms (REOB) are a waste product from the re-refining process of waste engine oil. There is a large incentive in the world to produce recycled engine oil and the production of REOB in this process is increasing. On the other hand refineries are going through transitions due to economic and regulatory reasons (i.e. IMO 2020) which has an impact on bitumen production process and its properties. As a result, harder grades bitumen are more readily available compared to the softer grades. Moreover, suppliers that are non-refiners are also part of the bitumen supply chain which has led to more variation in bitumen composition and properties. REOB, among other options of blending components, has posed a solution for this problem; making it possible to reach softer grade bitumen by blending the two. The pavement industry is however facing premature failures of pavements, less workable mixtures, earlier deterioration etc. and the question arises whether the diverse sources of blending components like REOB modification of the bitumen could be the cause of them. There exists no unique identification number (for example the CAS number used in the USA) for REOB as a material in Europe, which makes it untraceable when used in bitumen. While one is not obliged to notify contractors of the use of REOB, there also do not exist any guidelines for its use in asphalt mixtures; thus both the identification of REOB in bitumen as well as a clear evaluation of the bitumen properties and performance is wished for.
By using an extensive amount of chemical experimental tools like: Attenuated Total Reflectance Fourier-Transform Infrared Spectroscopy (ATR-FTIR), X-Ray Fluorescence (XRF), elemental analysis (CHNO+S), iatroscan chromatography (SARA fractioning), Gel Permeation Chromatography (GPC) and Differential Scanning Calorimetry (DSC) the characteristic properties of bitumen modified with REOB are mapped and identification and quantification of REOB in the bitumen is made possible. This is followed up by performing rheological experiments to map viscoelastic properties of the bitumen, using the Dynamic Shear Rheometer (DSR) and Bending Beam Rheometer (BBR). Mechanical performance of the bitumen and asphalt mixtures modified with REOB is evaluated by doing Dynamic Mechanical Analyser (DMA) tests on both cohesive/adhesive behaviour of stone-bitumen film and mastic column tests. Lastly, REOB modified asphalt mixtures are tested with Indirect Tensile (IDT) tests at dry and wet conditions and Cantabro Abrasion tests are done to evaluate impact resistance of the mixtures to simulate ravelling susceptibility.
Using the described approach, this study was able to present a methodology on how to analyse REOB modified bitumen to identify and quantify the presence of REOB and how to evaluate properties and performance of REOB modified bitumen and asphalt mixtures.

Asphalt pavements play a crucial role in constructing durable and sustainable road infrastructure. In recent years, with the advancement of sustainability and circular economy goals, reclaimed asphalt (RA) has been widely used in road construction. While the use of RA effectively reduces resource consumption and environmental impact, research on the fatigue and healing performance of asphalt mixtures and binders with high RA content remains relatively limited. This study aims to evaluate the healing performance of binder components from three asphalt mixtures commonly used in the base layers of Dutch pavements, employing multiple healing test protocols and healing indices. Two of these binders contain a high proportion of RA bitumen.

To achieve the research objectives, fatigue and healing tests were conducted on three different asphalt binders: Binder 1, composed entirely of fresh bitumen; Binder 2, a blend of high RA content bitumen with softer fresh bitumen; and Binder 3, which includes high RA bitumen content, fresh bitumen, and the rejuvenator. Fatigue performance was evaluated using Time Sweep (TS) and Linear Amplitude Sweep (LAS) tests to determine the fatigue life of each binder. Additionally, healing performance was assessed through single-rest period and multiple-rest period Time Sweep Healing (TS-H) tests, as well as Linear Amplitude Sweep Healing (LAS-H) tests. To evaluate healing performance, two different indices were used: the Healing Shift Factor (SFh), based on fatigue life extension, and the Healing Index (HI), based on modulus recovery.

The differences between single and multiple rest periods TS-H tests highlight the limitations of single rest period tests in fully capturing material healing capacity, indicating that more complex loading patterns should be explored for more comprehensive assessments. The variations in healing potential results across different test protocols and indices suggest that the healing performance of binders is highly sensitive to test protocol and indices selection.

Based on the described approach, a better understanding of the healing performance of different asphalt binders is achieved. Conclusions and future recommendations for research in this field were provided at the end of this research.

The widespread use of traditional bitumen, derived from finite crude oil resources, has led to growing concerns over its environmental impact, long-term availability, and cost. These challenges underscore the urgent need for sustainable, alternative binders in infrastructure applications such as road construction. Although previous research has explored bio-based and recycled waste materials as potential substitutes, these alternatives often fail to meet compatibility, durability, and performance standards.

To overcome these obstacles, this study employs a multifaceted methodology encompassing rheological, chemical, and mechanical analyses, along with environmental assessments. The objective is to develop an alternative binder synthesized from bio-based and waste materials that offers comparable or improved durability and performance. Our findings suggest that the alternative binder presents a viable replacement for traditional, petroleum-based bitumen. This innovation not only enhances the sustainability and circularity of road materials but also mitigates the construction industry's dependence on non-renewable oil resources.

The Netherlands has one of the densest road networks with over 140,000 km of roadways. Fatigue cracking is an important distress in flexible pavements. This form of distress results from the application of repeated traffic loading which causes failure. Fatigue cracking assessment on various base layer asphalt mixtures including reclaimed asphalt pavement materials and recycling agents has been addressed in this research work. This research work aims to develop a method for quantifying and assessing this fatigue characterization including the self-healing mechanism of asphalt mixtures using Visco Elastic Continuum Damage Theory. The self-healing in asphalt mixtures was assessed by incorporating group-rest healing periods in a self-developed laboratory testing method. The reliable self-healing models for asphalt mixtures with recycled asphalt materials and recycling agents based on temperature, damage state, and rest periods were predicted using the damage characteristics curve (C-S). Bottom-up cracking in base layer asphalt mixtures was modeled and studied using finite element modeling software FlexPAVE based on the Visco-Elastic Continuum Damage theory. A vivid assessment of mixtures for fatigue and healing characterization is discussed in this research work.

This research work is interrelated with an ongoing project, which aims at developing a protocol to determine the shift factors for the fatigue life of asphalt mixtures to correct healing and aging. The project runs under the umbrella of Knowledge-based Pavement Engineering (KPE), a joint program among Rijkswaterstaat, TNO, and TU Delft. Dura Vermeer is contributing partner to this MSc graduation research work as well.

This master's thesis addresses a critical gap in the field of road construction by focusing on the limitations of Styrene-Butadiene-Styrene modified bitumen (SBS-MB), a widely-used binder. While SBS-MB offers superior performance, its long-term efficacy is compromised due to various aging processes. Existing rejuvenators are insufficient for restoring the binder's original properties. To remedy this, our research introduces an innovative rejuvenator that provides a more comprehensive restoration of SBS-MB, especially in the reconstruction of the polymer network. The study employs a multifaceted evaluation approach, leading to an enhanced understanding of the rejuvenator's effectiveness and mechanisms of action. Furthermore, we validate the rejuvenator's efficacy using real-world, field-collected materials. The findings not only offer a more effective method for restoring aged SBS-MB but also hold promise for improving the recyclability of Reclaimed Asphalt Pavement (RAP), potentially leading to more sustainable road construction practices, particularly in the Netherlands.

SBS modified bitumen is popularly utilized in road construction owing to its outstanding performance and competitive pricing. However, like normal bitumen, SBS modified bitumen will also be aged and causing asphalt pavement distress and the need for maintenance, resulting in a significant amount of wasted modified asphalt. Recycling waste asphalt is critical for lowering road construction and maintenance costs, conserving original resources, and protecting the environment. Since recycled bitumen waste deteriorates over time, rejuvenators can be used to restore its properties. Many rejuvenators, on the other hand, only rejuvenate aged bitumen, and the excellent performance of SBS modified bitumen is largely attributable to the SBS polymer and polymer network structure in it. As a necessary consequence, it is critical to consider the simultaneous rejuvenation of both aged bitumen and degraded SBS polymer. 
In this research, SBS modified bitumen was aged with thin-film oven test (TFOT), followed by pressure aging vessel (PAV), and various contents and proportions of reference rejuvenators, physical rejuvenators, and chemical rejuvenators were applied to the aged bitumen. Dynamic shear rheometer (DSR) tests and Fourier transform infrared (FTIR) tests were conducted on aged and rejuvenated bitumen samples to study rejuvenation effects with different types of oil, SBS content, and chemical compounds by comparing rheological and chemical properties. The study showed that the rejuvenation effects of pure oil based rejuvenators are intimately connected to environmental temperature and oil molecular weight. High molecular weight oil provides better rutting resistance in high temperatures and low molecular weight oil provides better cracking and fatigue resistance at low temperatures. Rejuvenated bitumen with chemical rejuvenators performed admirably at high temperatures but with poor cracking and fatigue resistance in low temperatures. Increasing the SBS content in physical rejuvenators improves rutting resistance at high temperatures and reduces cracking resistance but partially improves fatigue resistance at low temperatures. The effects of different oil types and proportions for physical rejuvenators at high temperatures are a little complicated. In rejuvenators with low or medium SBS content, increasing proportion reduces performance, indicating oil is dominant now. In rejuvenators with high SBS content, increasing proportion improves performance, implying SBS is currently leading. For rejuvenators containing rapeseed oil and high SBS content, rising proportion barely affects performance, possibly because high viscosity oil has diminished the effect of high SBS content. For low temperature performance, physical rejuvenators with large molecular weight oil have the worst performance. Furthermore, increasing physical rejuvenator proportion improves the cracking and fatigue resistance of rejuvenated bitumen. In FTIR analysis, the polybutadiene group index IPB of rejuvenated bitumen with physical rejuvenators increases significantly and continues to rise as the proportion or SBS content increases. Moreover, the IPB index increases for rejuvenated bitumen with chemical rejuvenators, and a group of new absorption peaks in the spectrum demonstrated MDI had chemical reactions with degraded SBS polymer and had successfully connected the fracture SBS polymer segment.

A sustainable pavement, which can minimize environmental impacts through the reduction of energy consumption, natural resources and associated emissions while meeting all performance conditions and standards, is in urgent need to combat the climate change. The current scenario of depleting crude oil, reduced quarry zones, and stringent environmental regulations has driven the use of waste materials and by-products in pavement applications. The utilization of crumb rubber from scrap tires for bitumen modification has become a common engineering practice since last century...
@en

The high speed rail line in the Netherlands, constructed since 2002, is built to create a fast travel connection from Amsterdam to Rotterdam and the Belgium border. The track is designed for trains with a maximum operating train speed of 300 km/h. A great part of the structure is founded on typical Dutch soft soils consisting of Holocene clay and peat layers. To ensure high speeds, mostly settlement free plates with a ballastless track structure are constructed to produce optimum track qualities. At the village Rijpwetering a part of the track, parallel to the highway, has shown lateral deformations since construction. This has resulted in the research question “What are the main factors driving the horizontal deformation mechanism in the high-speed rail settlement free plate structure and what measures can be taken to solve these horizontal deformations?” The research consists of an analysis of the measurement results since 2005. From the measurement results a clear division can be made between the supported and the unsupported sections of the structure. The supported sections have almost stopped displacing in time with an average deformation rate of 0 to 0.5 mm per year. Unsupported sections show an ongoing deformation with a rate of 2.7 to 3.3 mm per year. This deformation will continue and lead to problems concerning structural safety due to bending moments in the top of the foundation pile. To identify the mechanism, a finite element modelling of the track structure embankment is performed from which the deformation behaviour is assessed. Multiple geometrical variants are considered which lead to asymmetrical horizontal deformations. From the simulations an asymmetrical soil layer with a varying stiffness in the subsoil on either side has led to the highest deformation behaviour. In other words, an embankment partly founded on soft soils (peat) and partly on stiff soils (sand). This can be identified as the main factor driving the horizontal deformation mechanism. The combination of different variants leads to results corresponding to the field measurements. To stop horizontal deformations the model is updated with 2 variants to observe the effectivity of the measures. One option is to apply a prestressed sheetpile wall, the other option is to reduce the structures weight with a low weight material (EPS). By applying a prestressed sheetpile in the slope of the embankment the resulting deformations can be stopped when applying a prestressing force of 100 to 150 kN. For the weight reduction, the EPS has to be placed in the slope on the soft soil. Reducing the weight with 144 kN/m or when applying EPS an area of 8.5mm2 stops further deformations. Applying weight reduction on the side of the stiff soil will only increase the problem and deformations will grow. Since weight reduction is usually a cheaper and a lower risk measure in comparison to prestressed sheetpile structures, it’s a very interesting alternative to investigate more accurately. Depending on the surrounding structures and construction possibilities the best option can be chosen to reduce deformations in this structure and prevent deformations in future structures.

The increasing traffic load has led to the use of polymer modifiers in bituminous mixes in order to improve the performance and the durability of the pavement structures. Epoxy is a thermoset material which ensures enhanced fatigue performance and improved mechanical characteristics when used to modify bituminous materials. However, unlike conventional modification techniques, a series of experimental methods have to be conducted to evaluate the chemical- related phenomena occurring during the binder production and their effects on the performance of the epoxy modified bitumen. For this reason in this thesis, the utilization of epoxy modifiers was investigated at binder level.
Initially, the chemical hardening (curing) process of epoxy modified bitumens (EMBs) was investigated by means of Fourier Transform Infrared (FT-IR) spectrometer and Dynamic Shear Rheometer (DSR). Different combinations of hardening conditions for three epoxy modification levels were studied. Properties, such as modulus and viscosity, were utilized to determine the workability of EMB. At the same time, by using the FT-IR spectrometer, the functional groups of EMBs during the chemical reactions were identified for the understanding of polymerization in the epoxy components.
Additionally, the DSR device was utilized to determine the fatigue and tensile strength of EMBs. It was found that, with increasing the content of epoxy modifier, the fatigue life and tensile strength were increased significantly compared to an unmodified binder.
Finally, the age hardening (aging) of EMBs was evaluated at different time intervals. For the simulation of short-term aging on EMBs, a short-term oven aging method (STOA) was used. For long-term aging, simulations were performed in a pressure aging vessel (PAV) under constant pressure and temperature. The results of chemical characterization and rheological properties of the aged EMBs were obtained by using DSR and FT-IR and were compared to the unmodified bitumen.

The use of synthetic fibres has been reported to enhance the performance of asphalt pavement materials in terms of permanent deformation, fatigue and thermal cracking. However, limited results about the benefits of synthetic fibres in the reinforced warm-mix asphaltic materials, and the exact mechanism of reinforcing the binding part in pavement structures is still unclear. This research aims firstly to examine the material at the warm mixed mortar level using a combination of two synthetic fibres (aramid and polyolefin) to conclude its fracture performance. Several laboratory tests were performed using specially designed experimental tools. Samples of three different fibre contents (0.05%, 0.1% and 0.5% of specimen weight) and two fibre lengths (19 and 38mm) were evaluated. In particular, pull-out tests, whose objective was to explore the interaction of fibre-matrix demonstrated a matrix-type of fracture; meaning that the adhesion of fibre-matrix is higher than the strength of the matrix itself, which implies a benefit of adding fibre to a mixture at high service temperature.
Summary
Moreover, direct tension tests were carried out with both monotonic and cyclic loading to measure the effect of the synthetic fibres on tensile strength, fracture energy and fatigue life of reinforced warm mixes under monotonic and cyclic tension load, respectively. These tension experiments concluded improvements on mechanical characteristics of warm mixed asphalt mortars when fibres were added, mainly applying higher dosages than the recommended by the fibres supplier. Overall, the current results elucidated that implementing dedicated material studies at micro-scales can assist on understanding the material performance and tailoring systems beyond sometimes recommended reinforcement dosages by the suppliers. Finally, a semi-circular bending test was performed as the largest scale of this research using various fibre amount composition as well as fibre length inside the bituminous mix, and the final results mainly correspond with the other examinations that have also been conducted. Therefore, the research methodology utilised in this thesis has been able to examine the reinforcement effect brought by the integration of synthetic fibre to failure performance of the warm mixed asphaltic mixture specifically regarding the cracking resistance extensively.