Papers by Michael WISTUBA
Assessing creep properties of asphalt binder, asphalt mastic and asphalt mixture
Road Materials and Pavement Design, Jan 11, 2022
Nanotechnology reviews, 2022
Recently, nanotechnology has been effectively used in the field of road pavement. Oxidation and a... more Recently, nanotechnology has been effectively used in the field of road pavement. Oxidation and aging of asphalt cause deterioration of road pavements and increase asphalt-related emissions. We propose an anti-aging strategy to interrupt the asphalt deterioration by using engineered clay/fumed silica nanocomposites. In this research, the morphological, chemical, thermal, mechanical, and rheological properties of nano-modified asphalt binders are meticulously analyzed in various conditions. The experiment results proved that this composite efficiently disrupts the chemical oxidation and decomposition in the mixture and reduces the aging rate. Remarkably, asphalt binder rheology experiments revealed that the addition of 0.2-0.3 wt% of nano-reinforced materials maximized their rheological resistance after shortand long-term aging. Moreover, nanoparticles improve the moisture resistance efficiency and in turn overcome the critical issue of moisture in low production temperature within the framework of warm mix asphalt technology. This costeffective, facile, and scalable approach in warm mix asphalt mixtures can contribute to increased sustainability and lifespan of pavements and a reduction in greenhouse gas emissions.
Accelerated Dynamic Shear Rheometer Fatigue Test for investigating asphalt mastic
Road Materials and Pavement Design, Apr 15, 2021
Asphalt mastic is known to play an important role when determining the fatigue performance of asp... more Asphalt mastic is known to play an important role when determining the fatigue performance of asphalt mixture. Time sweep test using a Dynamic Shear Rheometer can be used. However, a long testing time is a major disadvantage, and no guidelines for testing asphalt mastic are available. Therefore, this study presents an Accelerated Dynamic Shear Rheometer Fatigue Test (ADFT) for fatigue testing of asphalt binders and mastics. Asphalt binder of the types 50/70 and 25/55-55 A, and corresponding asphalt mastics were tested. The results were analysed in regard to consistency of test results, efficiency of testing time, and repeatability. ADFT showed better applicability than conventional time sweep test, and ADFT reduced testing time significantly. Repeatability was improved.
International Journal of Fatigue, Nov 1, 2017
Fatigue cracking is one of the primary failure mechanisms in asphalt pavements and it predominant... more Fatigue cracking is one of the primary failure mechanisms in asphalt pavements and it predominantly occurs within the mortar phase. For this reason, in recent years, a number of studies were carried out by various researchers to better understand the fatigue mechanism in such a critical mixture phase. In the present work, time sweep tests were performed in strain control mode on asphalt mortars prepared with three volume percentages of fine aggregate at different aging conditions. In particular, two different asphalt mortars were used: one containing Recycled Asphalt Pavement (RAP) materials and the other one composed of the same RAP aggregate skeleton without the aged binder. The influence of the different aging conditions, the presence of the aged binder and the addition of fine aggregate particles on the fatigue resistance of the mortars were evaluated. Moreover, a relationship between the parameters of the obtained fatigue laws and the different aging and mix design conditions was found. The proposed relationship can be easily used to predict the fatigue resistance of a mortar composed of a specific volume concentration of aggregate particles and recycled material. The potential extension of the proposed relationship to mixtures may eventually result in the implementation of a simple analysis tool for practitioner limiting the need for more sophisticated and expensive fatigue tests on asphalt mixtures.
Lecture notes in civil engineering, Aug 30, 2019
The gasification industries make use of biomass residue as feedstock to produce synthesis gas, bu... more The gasification industries make use of biomass residue as feedstock to produce synthesis gas, but the gasification of this waste biomass generates tons of ash everyday. Performance properties and agglomeration behavior of corncob ash (CCA) collected from the gasification of corncobs in a pilot-scale gasification station were investigated by using some experimental methods. Based on the chemical composition results, the agglomeration tendency of CCA from combustion and gasification process was also analyzed. Chemical analysis shows that the fly ash is mainly composed of inorganic matters formed by K, Mg, Ca, Na, Fe, Al, S, etc. The agglomeration characteristics indicate that the slagging degree increases with the increase of ashing temperature, and the slagging tendency of these CCA samples from gasification or combustion is different with various slagging indices. All CCA samples from combustion or gasification can cause slagging/fouling problems in thermal conversion systems. The applications of CCA are closely related to its performances, and CCA has the potential to be used in various fields, for example, as a material for ceramic products and activated carbon, as an adsorbent, as a crude fertilizer, and as a structural material.
Frontiers in Materials, Feb 17, 2022
A novel Three-Point Bending Beam Test (3-PBT) using a Dynamic Shear Rheometer (DSR) with linear d... more A novel Three-Point Bending Beam Test (3-PBT) using a Dynamic Shear Rheometer (DSR) with linear drive motor is introduced for testing asphalt binder at low temperature conditions. This 3-PBT in DSR can be used as surrogate for Bending Beam Rheometer (BBR) tests. Advantages in comparison to BBR are that (i) 3-PBT works without harmful cooling medium ethanol, (ii) the amount of asphalt binder for testing is significantly lower (using material equivalent of 10% of BBR tests), (iii) a silicone rubber mold is used for specimen preparation instead of standard aluminum mold for BBR tests, which makes handling easier, and (iv) the loading protocol is more practical without applying contact load manually. The novel 3-PBT in DSR is presented with respect to preparation, installation, and conditioning of specimens, as well as to the loading protocol. Tests were conducted at temperatures of −10, −16, and −20°C. For the purpose of comparison to BBR tests, and of identifying most suitable testing conditions from alternative setups, a test series was run including 9 different asphalt binders. As to BBR tests, two different cooling media were used, i.e., ethanol and air. Finally, all test results obtained from DSR and BBR tests were analyzed in view of precision and correlation. DSR results correlated well with BBR results, while precision of 3-PBT in DSR was found to be satisfying.
GPR as a crack detection tool for asphalt pavements: Possibilities and limitations
2012 14th International Conference on Ground Penetrating Radar (GPR), Jun 1, 2012
Cracking in asphalt pavement is a distresses often requiring urgent measures. GPR has been proved... more Cracking in asphalt pavement is a distresses often requiring urgent measures. GPR has been proved by numerous scientists as a fast and reliable asphalt pavement characterization tool. Whether GPR can be applied as a crack detection tool is a question to be answered. To find out the influencing parameters, e.g., crack fill, atmospheric condition, etc., GPR surveys were carried out on asphalt test pavements. Multiple techniques were used for data processing. Possibilities and limitations are documented.
Consideration of Climatic Conditions in Pavement Design
CRC Press eBooks, Dec 20, 2021
Climate strongly influences the bearing capacity and the stiffness of pavements. Therefore climat... more Climate strongly influences the bearing capacity and the stiffness of pavements. Therefore climatic effects are very important in a modern pavement design procedure. In order to optimize a pavement construction and to increase its long-term performance, the specific local climate has to he considered in the design process. The Austrian analytical design procedure for asphalt pavements is an example of considering the climatic conditions in the design calculation. The consideration of climatic parameters is based on the seasonal temperature distributions in the asphalt layer. Design temperatures are classified referring to the local Austrian climates. The paper presents the results of latest research at the Institute for Road Construction and Maintenance at Vienna University of Technology, which mainly aims at an improvement of the Austrian pavement design procedure. For the covering abstract see ITRD E118503.
CRC Press eBooks, May 21, 2015
Rilem bookseries, Sep 13, 2018
Rutting is one of the most severe failure mechanisms for asphalt pavements. This phenomenon is du... more Rutting is one of the most severe failure mechanisms for asphalt pavements. This phenomenon is due to the accumulation of permanent deformation in consequence of traffic loading. The behavior of asphalt mixture is highly affected by the properties of the asphalt binder used in the mix design. For this reason, the Multiple Stress Creep and Recovery (MSCR) test procedure was recently introduced with the objective of better evaluating the rutting resistance while replacing the conventional Superpave parameter, G*/sind. Good understanding of the rutting mechanism within the asphalt binder component is essential for correctly studying the mutual interactions of the asphalt mixture components: binder, fine aggregate and large particles. This paper presents the results of an experimental campaign consisting of MSCR tests performed on asphalt binder, mastic and fine aggregate mixture which compose a typical mixture for asphalt binder layer. All the tests were conducted using a Dynamic Shear Rheometer (DSR). The classical plate-plate configuration having 25 mm diameter and 1 mm gap was selected for asphalt binder and mastic tests. The cylindrical geometry was used for torsional tests on fine aggregate mixture presenting aggregate as large as 1.16 mm. A single testing temperature of 60°C and three different stress levels, 100, 1600, 3200 Pa, were imposed. The results indicate that creep and recovery are functions of filler concentration and stress level.
Investigation of asphalt recovery properties in fatigue test with single rest period
CRC Press eBooks, May 21, 2015
Experimental Investigation on the Effect of Rejuvenator on the Use of a High Amount of Recycled Asphalt Binder
Lecture notes in civil engineering, 2020
Due to economic and environmental benefits, Recycled Asphalt Pavement (RAP) has been commonly use... more Due to economic and environmental benefits, Recycled Asphalt Pavement (RAP) has been commonly used in the asphalt pavement construction. However, the capability of existed mixing plants to incorporate a high percentage of RAP restrict the use of a high RA content. In this study, the possibility of recycling a RA binder content of 80% is experimentally investigated. First, an unmodified 50/70 binder is selected as the reference material; then, an extracted RA binder was blended with the optimal rejuvenator, and the rejuvenator content determined based on the penetration test to restore the original penetration value close to the reference material. Next, both materials are artificially aged to short- and long-term aging conditions. Rheological tests are performed with the Dynamic Shear Rheometer (DSR) and the Bending Beam Rheometer (BBR). Finally, the experimental results are used to evaluate the performance property of virgin and rejuvenated asphalt binders under different aging levels. Results indicate that the properties of the blend of RA and virgin binder can be only partially restored by the action of the rejuvenator.
Transportation research procedia, 2016
The use of recycled materials in asphalt pavements increased significantly over the years, determ... more The use of recycled materials in asphalt pavements increased significantly over the years, determining well known environmental and economic benefits. Many research agencies and road authorities evaluated the impact of Recycled Asphalt Pavement (RAP) on pavement performance. Nevertheless, the mechanism governing the interaction between virgin asphalt binder and aged RAP binder is not well understood. In this paper, the effect of RAP on the rheological properties of asphalt binders and mortars is experimentally evaluated, and theoretically modeled with the objective of defining a relationship between the linear viscoelastic (LVE) properties of binders and those of the corresponding mortars.Three asphalt binder types, obtained by blending a hard and a soft binder at three different percentages, were mixed with three different contents of a Selected fraction of Recycled Asphalt Pavement, called SRAP, for preparing the asphalt mortar samples. Dynamic Shear Rheomether tests were performed on binders and mortars to determining the complex modulus over a wide range of temperatures and frequencies. The rheological properties of the compound of virgin and RAP binder were evaluated by using a new approach based on a modified version of the Nielsen model, avoiding the extraction and recovery method.The results were then modelled by using the analogical 2S2P1D model, consisting of one spring, two parabolic and one-dashpot elements combined in series and then assembled together with a second spring in parallel. Based on test results, a simple experimental relationship between the characteristic times of the binder and the percentage of RAP in the mortar was found.
Low-temperature performance prediction of asphalt mixtures used for LLP—new approach based on fundamental test methods and numerical modeling
International Journal of Pavement Engineering, Jun 13, 2006
A major mode of deterioration in fully-flexible long-life pavements (LLP) is surface-initiated to... more A major mode of deterioration in fully-flexible long-life pavements (LLP) is surface-initiated top–down cracking. If surface maintenance is suspended, surface-initiated cracks may conflict the long-life concept, as they will propagate into the structural layers and structural deterioration will start. The risk of surface-initiated top–down cracking is influenced by a number of interacting factors. Critical stresses may result, e.g. from the
Evaluation of hot-mix asphalt susceptibility to temperature-induced top-down fatigue cracking by means of Uniaxial Cyclic Tensile Stress Test
Road Materials and Pavement Design, Mar 1, 2012
A dominant failure mode in hot-mix asphalt (HMA) layers is material fatigue, occurring when the a... more A dominant failure mode in hot-mix asphalt (HMA) layers is material fatigue, occurring when the asphalt layer is repeatedly loaded by tensile stresses. The maximum stress arises at the bottom of the asphalt layer and, in consequence, crack development is initiated at the bottom. Various techniques are known that simulate bottom-up fatigue cracking in the laboratory. Fatigue failure is also
Construction and Building Materials, Aug 1, 2016
This paper presents a simple method to determine the amount of Reclaimed Asphalt Pavement (RAP) t... more This paper presents a simple method to determine the amount of Reclaimed Asphalt Pavement (RAP) that can be added to Stone Matrix Asphalt (SMA) mixtures without compromising the fatigue resistance. Dynamic Shear Rheometer tests (DSR) on binder and mortars composed with fine RAP particles, called Selected Recycled Asphalt Pavement (SRAP) are used together with the Nielsen model to backcalculate the norm of the complex modulus of the bituminous blend of fresh and RAP binder. Fatigue properties are derived from parameter G*sind and Linear Amplitude Sweep tests. The analysis indicates that a limiting SRAP binder content of 23% can be included in SMA mixtures with satisfactory fatigue performance.
Warm mix asphalt technology: An up to date review
Journal of Cleaner Production, Sep 1, 2020
Abstract The purpose of the current review is to give an insight into various Warm Mix Asphalt (W... more Abstract The purpose of the current review is to give an insight into various Warm Mix Asphalt (WMA) techniques in pavement engineering. The idea is to provide a comprehensive overview of this technology that may serve as a basis for engineers and practitioners to structure the entire processes, associated with the design and construction of roads, under healthier and safety-oriented working conditions while following an environmentally friendly conscious approach. This manuscript provides an up-to-date review of WMA technologies. The paper also presents and compares several studies on the most common additives, mix design and environmental benefits of this production method. Also, this review discusses the improvement in physical, mechanical properties and durability of pavement designed with WMA mixtures.
Risk Evaluation of Surface-Initiated Cracking in Asphalt Pavements by Means of Fundamental Laboratory Tests and Numerical Modelling
10TH INTERNATIONAL CONFERENCE ON ASPHALT PAVEMENTS - AUGUST 12 TO 17, 2006, QUEBEC CITY, CANADA, 2006
Surface-initiated cracking is rated among the most significant forms of deterioration in asphalt ... more Surface-initiated cracking is rated among the most significant forms of deterioration in asphalt pavements that are designed based on the criterion of fatigue. In this study experimental work, material modeling of asphalt, and computational mechanics are combined for getting new insights into the formation of critical tensile stresses, arising in a pavement structure from extreme temperature cooling and from heavy traffic loading. A numerical pavement model is subjected to realistic temperature cooling scenarios derived from meteorological data, and to traffic loading, allowing us to separate traffic-associated from temperature-associated stresses. Special attention is paid to long-time loading in consequence of temperature changes and to the incorporation of the effect of temperature changes on material properties. The respective results from numerical simulation of critical stresses serve as input for the second step, the laboratory experimentation. A cyclic tensile stress test is employed, where an asphalt specimen is subjected to a constant tensile stress for simulating temperature associated stresses and to an additional cyclic loading in order to simulate traffic associated stresses. As a result, the risk of cracking for the investigated asphalt material is evaluated, and consequently, the recipe of the respective mixture can be optimized with regard to its in-service low-temperature performance.
Bruchmechanische Pruefverfahren fuer Bitumen und Asphalt
Der Beitrag stellt verschiedene bruchmechanische Pruefverfahren fuer die Untersuchung des Risswac... more Der Beitrag stellt verschiedene bruchmechanische Pruefverfahren fuer die Untersuchung des Risswachstums von Bitumen und Asphalt vor. Fuer Bindemittelpruefungen liegen international veroeffentlichte Erfahrungen mit Biegeversuchen an gekerbten Probekoerpern sowie einaxialen Zugversuchen mit doppelt gekerbten Proben vor. Fuer die Beurteilung des Widerstandes von Asphaltprobekoerpern gegen Risswachstum wurden Veroeffentlichungen zu Biegeversuchen an gekerbten prismatischen oder halbkreisfoermigen (Semi-Circular Bending Test) Proben, dem Kerbspaltversuch sowie dynamischen Zugversuchen ausgewertet.
Haftverhalten zwischen Bitumen und Gestein - neue Verfahren zur Beurteilung
Bei Strassenbauasphalten ist das Haftverhalten, also die dauerhafte Klebewirkung zwischen Gestein... more Bei Strassenbauasphalten ist das Haftverhalten, also die dauerhafte Klebewirkung zwischen Gestein und Bitumen beziehungsweise Mastix, eine wesentliche Gebrauchseigenschaft. Zurzeit sind zielsichere Anforderungen an die Hafteigenschaften in Strassenbauasphalten weder im nationalen Regelwerk noch in der Europaeischen Norm enthalten. Es fehlt, trotz einer Vielzahl an vorhandenen Testmethoden, ein umfassend anerkanntes Pruefverfahren, das praezise die Hafteigenschaften zwischen Bindemittel und Gestein anspricht und anhand eines physikalischen Parameters zum Ausdruck bringt. Das Institut fuer Strassenwesen der Technische Universitaet Braunschweig (ISBS) fuehrte umfangreiche Vergleichsuntersuchungen an bekannten Pruefverfahren durch, mit dem Ziel, diese hinsichtlich ihrer Praxisadaequatheit und Aussagekraft zu beurteilen. In Anlehnung an den in Deutschland bekannten Spaltzugfestigkeitsabfall nach Wasserlagerung wurde dabei der am ISBS entwickelte Zugversuch an prismenfoermigen Asphaltprobekoerpern vergleichsweise mit betrachtet. Ausgehend von diesen Untersuchungen wurde ein neuer Versuchstyp entwickelt, bei dem die Zugfestigkeit eines bitumenverklebten Gesteinsstiftes vor und nach Wasserlagerung analysiert wird. Dieser Versuchstyp wird im Beitrag vorgestellt. Angestrebtes Ergebnis ist es, mithilfe des neuen Versuchstyps Kenngroessen ableiten zu koennen, mit deren Hilfe die Hafteigenschaften zwischen Gestein und Bitumen eindeutig, ausreichend praezise und laboroekonomisch nachweisbar sind. Der Bericht gibt einen Ueberblick zu den gewaehlten Ansaetzen und zum Stand der Untersuchungen. Obwohl die Entwicklung dieses Versuchstyps noch nicht abgeschlossen ist, zeichnen sich schon jetzt Vor- und Nachteile ab. (A) (Beitrag zur Asphaltstrassentagung 2013 in Duesseldorf.)
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Papers by Michael WISTUBA