Di Wang

Aalto University · Department of Civil Engineering

The Multiple Stress Creep and Recovery test is recognised to better characterise the high-temperature property of bituminous binders than the traditional methods, especially for polymer modified bitumen (PmB). However, some experimental parameters may affect the test results, such as the preloading, measurement location, stress level. In this study...

This paper investigated the effect of waste polyethylene (PE) on the modified asphalt binders' rheological behavior from a statistical point of view. The Interlaboratory testing results from the RILEM Technical Committee (TC) 279 WMR (Valorization of Waste and Secondary Materials for Roads) Task Group 1 (TG1) were used for this purpose. First, an u...

In order to conserve non-renewable natural resources, waste cooking oil (WCO) in bitumen can help lower CO2 emissions and advance the environmental economy. In this study, three different components of WCO were isolated and then, together with polyphosphoric acid (PPA), used separately as bitumen modifiers to determine the suitability of various su...

In the present study, the effects of adding fibers and Reclaimed Asphalt Pavement (RAP) on the low temperature performances of open graded asphalt mixtures for surface layer and dense asphalt mixtures for surface, binder, and base layers were investigated. Two different kinds of fibers were used: a combination of aramid and polyolefins fibers were...

The use of distinctive and decorative self-luminous pavements for motorized traffic has dramatically increased worldwide. In this research effort, the composition and optical characteristics of four colors (sky-blue, blue-green, yellow-green, and red) of luminescent powder (LP) were characterized by chemical and physical means. Next, the mechanical...

Global warming is driving the search for emissions-free energy sources. This study proposes a novel road thermoelectric generator system (RTEGS) based on the Seebeck effect, which transforms the thermal of asphalt pavement into electricity. The RTEGS comprises asphalt pavement, a thermoelectric generator, and a cold-side module. Finite element simu...

The constant demand for high-performing and more reliable roads has led to an increasing use of complex bituminous binders such as polymer-modified bituminous binders, which has become a widespread practice for asphalt pavement. As a result, specification and testing have evolved to better distinguish between quality materials. In recent years, mor...

In this project, the adhesion property and moisture effect between styrene–butadiene–styrene (SBS) modified asphalt binder and aggregate were studied to reveal their interface adhesion mechanism. The influence of SBS contents on adhesion property and moisture effect between binder and aggregate phases were investigated using molecular dynamics simu...

Conventional asphalt pavement has a deep surface color and large thermal inertia, which leads to the continuous absorption of solar thermal radiation and the sharp rise of surface temperature. This can easily lead to the permanent deformation of pavement, as well as aggravate the urban heat island (UHI) effect. Cool pavement with a reflective coati...

This research aims to determine if the observed improvements using polyethylene (PE) waste in asphalt binder translate into better performance at the asphalt mixture scale in the laboratory environment while overcoming the stability and homogeneity issues experienced at the binder level. This is accomplished through a round-robin multinational expe...

Crumb-rubberized asphalt (CRA) binder has been widely used for several decades because it provides a nonhazardous disposal method for scrap tires and it improves some engineering properties of asphalt pavement. The energy consumption, atmospheric emissions, and storage stability of CRA binder are the issues limiting wider use of it. This study prov...

This study investigates the molecular mechanism of used oil on improving the compatibility and viscosity reduction of rubberized asphalt (RA) using molecular simulations and lab tests. This validates the feasibility of producing waste oil modified RA while enhancing the sustainable use of resources and pavement performance. The model of RA with use...

In this present study, the effects of polyacrylonitrile fibres and high content (50%) of Reclaimed Asphalt Pavement (RAP) on the mechanical properties of asphalt mixtures in binder and base layers were studied. This is the first time that the effect of high RAP content on the mechanical properties of fibre reinforced asphalt mixtures (FRAM) was eva...

To investigate the aging differences of asphalt films in the vertical aggregate direction, a three-layers model of oxygen-asphalt-aggregate was generated to explore the molecular mechanism of gradient aging. Moreover, the asphalt-aggregate specimens aged for 10, 20, and 40 h were layered for three parts. Fourier transforms infrared spectroscopy and...

Significant volumes of waste materials such as plastics is generated every year worldwide with a potentially harmful impact on the environment. At the same time, the demand for asphalt modifiers has seen an increase over the year with consequent higher costs for these types of additives. Therefore, combining large amounts of available waste plastic...

In this study, a method that can be used to replicate the Fine Aggregate Matrix (FAM) in the field condition as accurately as possible was experimentally validated, and the low temperature performance was measured and evaluated. First, an AC 22 TS mixture is selected as the reference material. The method based on a shift of the grading curve by a m...

This recommendation is based on the results of an inter-laboratory study organised by the RILEM technical committee TC 264-RAP "Asphalt Pavement Recycling"—Task Group 3 (TG3) focusing on Asphalt Binder for Recycled Asphalt Mixture. The TG3 aimed to evaluate the effect of a specific family of materials known as asphalt recycling agent (ARA) on the a...

The use of rejuvenators has seen a consistent increase over the years in the asphalt pavement industry. This is due to the need for maximizing the demand for incorporating a higher amount of Reclaimed Asphalt (RA) in the pavement asphalt mixtures. In order to tackle this challenge, the Task Group 3, focusing on asphalt binders and additives, of the...

Cold recycling with foamed asphalt is a sustainable pavement rehabilitation technology and becomes more widely applied in many countries. However, there are still some ongoing scientific debates on the issues such as cold recycling mix design, pavement structural design and analysis. Many popular mix design methods adopted indirect tensile strength...

The research was carried out to explore the effect of silica nanoparticles (NPs) on the ultraviolet aging properties of bitumen. In this study, characterization of NPs-modified Bitumen using scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FT-IR), and ultraviolet-visible spectrophotometer were investigated. In addition,...

In this paper, the effect of the combined use of re-recycled Reclaimed Asphalt Pavement (RAP) on the performance properties of Warm Mix Asphalt (WMA) was experimentally investigated at both binder and mixture scales. First, a virgin 50/70 Pen Grade binder and fresh Gabbro aggregates were used to prepare a conventional Hot Mix Asphalt (HMA) for surf...

Inter-laboratory experiments were designed to evaluate the impact of plastic waste blended directly in bitumen and to assess the properties, using conventional and advanced bituminous binder testing. The blends targeted 5% of plastic waste in 95% bitumen, using two types of polyethylene (PE) primary (pellets) and secondary (shreds) waste. The exper...

Sustainable and resilient pavement infrastructure is critical for current economic and environmental challenges. In the past 10 years, the pavement infrastructure strongly supports the rapid development of the global social economy. New theories, new methods, new technologies and new materials related to pavement engineering are emerging. Deteriora...

Rubberized asphaltic materials have been frequently combined with warm-mix asphalt technologies to tackle the issues of high energy consumptions and emissions during construction. Effective and accurate characterization of binder properties is conducive to the improvement of long-term pavement performance. The current study aims to quantify the eff...

This work presents an investigation of the three-dimensional linear viscoelastic behavior of asphalt mixtures containing different percentages of Recycled Asphalt Pavement (RAP) materials. Cyclic tests in tension-compression were performed on cylindrical samples in strain-controlled mode, measuring the axial and transverse deformations. Complex mod...

Various rejuvenators already enable an increased amount of reclaimed asphalt pavement (RAP) within the mix design of hot mix asphalt (HMA). The aged RAP binder presents higher values of softening point compared to the virgin binder. Therefore, the use of rejuvenators has the potential to improve the characteristic of the final mixture. However, it...

In this laboratory study, combined effects of polyacronitrile fibres and reclaimed asphalt planings on performance properties of asphalt mixtures were investigated. Performance properties of six asphalt mixtures in total were comparatively analyzed, always considering a standard mix design concept for asphalt binder courses. Three asphalt mixtures...

The asphalt emulsion cold recycled mixture (CRME) technology is one of the main utilization method when RAP is used in the asphalt pavement construction. However, there is not a unified material design method for this technology. In this paper, according to the Marshall test method, the test samples were prepared by two molding methods: one-time co...

The use of fibers in porous asphalt (PA) mixtures to enhance the performance properties of asphalt pavement have become an attractive technology in recent years. In this study, the combined effect of fiber reinforcement and aging conditions on the mechanical properties at low and intermediate temperatures of the asphalt mortar phase of porous aspha...

Due to economic and environmental benefits, Recycled Asphalt Pavement (RAP) has been commonly used in the asphalt pavement construction. However, the in-crease in stiffness and brittleness of asphalt binder restrict the use of a high RA con-tent. In this study, the possibility of recycling a RA binder content of 80 % is exper-imentally investigated...

The growing use of reclaimed asphalt (RAP) results in a continuous increase in the percentage of added RAP to hot mix asphalt. Within the asphalt pavement, the asphalt binder is the component which is affected the most by the ageing during service life, resulting in considerable hardening of the RAP binder. Therefore, the aged binder needs to be re...

The cohesion and adhesion behavior (CAB) in binder-aggregate interface are statistically related to asphalt pavement performance. Although numerous test methods have been developed to evaluate the CAB, the difficulties, such as the classification on failure types of CAB and decisions on test results, still need to be further investigated. In this s...

This paper investigates the effect of the glass transition temperature, Tg, and the use of modulus shift factors bT on the measured rheological properties of asphalt binders at low temperatures. First, temperature-frequency (T-f) sweep tests are performed with the Dynamic Shear Rheometer (DSR) on asphalt binder, and, the corresponding Tg is calcula...

The application of additives in asphalt mixtures to enhance the performance properties of asphalt pavements has become an attractive approach in recent years. Several studies have confirmed that the incorporation of fibers into bituminous materials can improve the durability of the pavement. However, whether a single optimum fiber content can impro...

Thermal cracking is one of the most common distresses for asphalt pavement constructed in the cold regions. In order to address this issue, the combined use of fracture mechanics-based tests and simulation is a solid option. First, asphalt mixture samples are prepared based on the German standard and the low temperature strength are measured by Sem...

The use of porous asphalt (PA) mixture to build the wearing course is in some countries common practice to enhance durability and performance of asphalt pavements. Meanwhile, a number of studies have been conducted to evaluate the possibility of improving the pavement performance through the incorporation of fibers at the binder and mixtures level....

In this paper, five rheological models, including a newly developed formulation based on the combination of the Christensen-Anderson-Marasteanu (CAM) model and the sigmoidal function, are used to evaluate the dynamic modulus of three different asphalt mixtures types. The effectiveness of the models in representing the experimental results is graphi...

In this paper, three different rheological models including a newly developed formulation based on the current Christensen Anderson and Marateanu (CAM) model, named sigmoidal CAM model (SCM), are used to estimate the evolution of roughness, rutting, and reflective cracking in a typical composite pavement structure currently widely adopted in South...

In this paper, the combined use of re-recycled reclaimed asphalt pavement (RAP) and Electric Arc-Furnace Steel Slag (EAFSS) is experimentally investigated and evaluated. First, a virgin asphalt mixture for surface layers is prepared and next aged in the laboratory to reproduce artificial RAP. Then, this material is used to prepare a set of first ge...

In this paper, the possibility of using different amounts of re-recycled (repeated recycled) Reclaimed Asphalt Pavement (RAP) in the asphalt mixture was experimentally investigated. First, a single virgin mixture was prepared and artificially aged to simulate the first generation of RAP to be used for designing the first generation of recycled mixt...

The 4 mm parallel plate geometry in the DSR with a new sample installation method is proposed to evaluate low temperature rheological properties of asphalt binders. For this purpose, the influences of temperature conditioning and normal force were studied, and finally suitable test conditions were identified to run T-f-Sweep tests in oscillation mo...

Due to the environmental and economic benefits, the temperature reduction production process during the asphalt mixture attracts more and more attention. In this study, the effects of temperature reduction production process and experimental conditions on asphalt binder rheological properties, especially for low temperature and aging properties, ar...

In this paper, the effect of physical hardening and aging temperatures on the low temperature rheological properties of the asphalt binder is experimentally investigated and modeled. First, Dynamic Shear Rheometer (DSR) tests are performed from -30ºC to 80ºC on four virgin asphalt binders and the corresponding long-term aged binders, which were pre...

In this paper, the combined use of re-recycled reclaimed asphalt pavement (RAP) and Electric Arc-Furnace Steel Slag (EAFSS) is experimentally investigated and evaluated. First, a virgin asphalt mixture for surface layers is prepared and next aged in the laboratory to reproduce artifi-cial RAP. Then, this material is used to prepare a set of first g...

This paper evaluates whether the temperature reduction production during Warm-Mix Asphalt (WMA) leads to a beneficial effect on short- and long-term aging properties of asphalt binder. For this purpose, two 70/100 penetration grade virgin asphalt binders were used. First, the material was short term aged at three different temperature, 123 ºC, 143...

In this paper, the possibility of repeated recycling (re-recycling) of reclaimed asphalt pavement (RAP) is experimentally evaluated. First, a virgin asphalt mixture with asphalt binder PG 58-28 and maximum aggregate size equal to 12.5mm was prepared. Then, the virgin mixture was artificially aged to simulate the different generations of recycled ma...

In this paper, the combined effect of aging temperatures and cooling medium on the rheological properties of asphalt binder was experimentally investigated and evaluated. Two 70/100 penetration grade binders, which were part of the core materials used by the active RILEM committee CMB-252, were selected for this purpose. The materials were artifici...

In this paper, the combined use of reclaimed asphalt pavement (RAP) and rejuvenators for producing hot recycled asphalt mixture is investigated based on the new Bitumen Typisierungs Schnell Verfahren - BTSV method (Binder-Fast-Characterization-Test), recently proposed in Germany, and through laboratory experimentation. For this purpose, a set of th...

As the use of warm and cold asphalt mixing technologies provides an opportunity to save energy during production, it is important to determine if this lower mixing temperature also has a long-term effect on the binder chemical and rheological properties and performance. In this study, a link between the chemistry and rheology of bituminous binders...

Using reclaimed asphalt material for rehabilitation and construction of new asphalt pavements is currently a common practice not only in view of the economic benefits associated with this process but also because of the reduced exploitation of natural resources. For this reason, road authorities implemented recommendations and guidelines to regulat...

In this paper, the possibility of using the Dynamic Shear Rheometer (DSR) with 4 mm parallel plates and 3 mm gap is investigated as an alternative experimental method to measure the rheological properties of asphalt binders at low temperature. A special butterfly silicone mold was prepared for this purpose and the corresponding testing procedure wa...

In Germany, Warm Mix Asphalt (WMA) is not commonly used although this technology was initially introduced to the practice between the 60s and the 80s. The current guidelines are devoted to the reduction of the mixing temperature for mastic asphalt (MA) (Gussasphalt). Due to this requirement, a number of products consisting of plain or polymer modif...

Low-temperature properties of asphalt binders are fundamental for designing asphalt mixture in cold regions. This is especially true for alternative technologies such as Warm Mix Asphalt (WMA), for which a temperature reduction during production may potentially lead to substantial benefits in terms of long-term aging conditions. At low temperature,...

This study reviewed and compared the test methods for the high-temperature performance of asphalt binder, and selected Repeated Creep Recovery (RCR) test to evaluate the high-temperature performance of three wasted-based high-viscosity asphalt binders (WHABs, including D-I, D-II and F) and a control sample (TAFPACK-SUPER modified asphalt, TMA). Mea...

In this paper, the low temperature behavior of asphalt mixture containing Reclaimed Asphalt Pavement (RAP) was experimentally and numerically investigated. For this purpose, four asphalt mixtures prepared with different percentages of RAP were tested with the Bending Beam Rheometer (BBR) to determine their creep stiffness, S(t). Then, the S(t) of t...

This paper presents an experimental investigation on the combined use of high content of reclaimed asphalt pavement (RAP) and rejuvenators, for producing asphalt mixtures for wearing courses. First, the new Binder-Fast-Characterization-Test (Bitumen Typisierungs Schnell Verfahren in German) BTSV method, recently proposed in Germany, is used to dete...

In this paper, the low temperature behavior of asphalt mixture containing Reclaimed Asphalt Pavement (RAP) was experimentally and numerically investigated. For this purpose, four asphalt mixtures prepared with different percentages of RAP were tested with the Bending Beam Rheometer (BBR) to determine their creep stiffness, S(t). Then, the S(t) of t...