Lidé na fakultě
doc. Ing. Otakar Vacín, Ph.D.

2023, Road Materials and Pavement Design, 24 (7), p. 1820-1836), ISSN 2164-7402

Although the MSCR test has become an improvement over the Superpave® |G*|/sinδ parameter, shear stress levels specified in the MSCR test might prove to be too low to successfully represent the stresses occurring in the pavement. To address this hypothesis, five conventional asphalt binders and a total of twelve polymer-modified asphalt blends were tested by MSCR at two different temperatures (50°C and 60°C) as well as five different shear stress levels of 0.1, 3.2, 6.4, 12.8, and 25.6 kPa. The rut results of hot mix asphalts were correlated with the MSCR results. Consequently, better correlations were obtained at higher shear stress levels used in performing MSCR. Moreover, it was shown that MSCR test overestimated the positive effects elasticity on the asphalts’ rut resistance and, thus, more consideration should be given to the asphalt’s ability to resist the applied stresses than to its elastic recovery.

Článek v periodiku excerpovaném SCI Expanded

2019, International Conference on Advances in Civil and Environmental Engineering (ICAnCEE 2018), Les Ulis Cedex A, EDP Sciences - Web of Conferences), ISSN 2261-236X

The sustainable use of non-renewable natural resources, such as asphalt binder, can be achieved by adequate planning. The proper assessment of asphalt binders is a prerequisite to the appropriate designing of road constructions that can eventually result in pavements in which the development of pavement distresses can be mitigated. Rutting is the most common distress occurring at high temperatures, which is frequently experienced by such countries as Indonesia; thus, the use of adequate asphalt binder in hot mix asphalt pavements results in long-lasting road constructions. By means of advanced techniques, e.g., multiple stress creep recovery test, conducted on a dynamic shear rheometer, it is possible to determine the rutting potential of asphalt binders. This technique, however, still seems to be imprecise at currently determined shear stress values. This paper aims to investigate on the example of ten different asphalt binders, if creep and recovery measured at higher shear stresses result in better correlation with rutting potential of hot mix asphalts than that at the standardized stress levels. Concurrently, other conventional asphalt binder properties (e.g., penetration, softening point, elastic recovery) are determined and compared with rutting.

Stať ve sborníku z prestižní konf.

2018, Book of Abstracts of International Conference on Advances in Civil and Environmental Engineering, Bali, University of Udayana), p. 122-122)

The sustainable use of non-renewable natural resources, such as asphalt binder, can be achieved by adequate planning. The proper assessment of asphalt binders is a prerequisite to the appropriate designing of road constructions that can eventually result in pavements in which the development of pavement distresses can be mitigated. Rutting is the most common distress occurring at high temperatures, which is frequently experienced by such countries as Indonesia; thus, the use of adequate asphalt binder in hot mix asphalt pavements results in long-lasting road constructions. By means of advanced techniques, e.g., multiple stress creep recovery test, conducted on a dynamic shear rheometer, it is possible to determine the rutting potential of asphalt binders. This technique, however, still seems to be imprecise at currently determined shear stress values. This paper aims to investigate on the example of ten different asphalt binders, if creep and recovery measured at higher shear stresses result in better correlation with rutting potential of hot mix asphalts than that at the standardized stress levels. Concurrently, other conventional asphalt binder properties (e.g., penetration, softening point, elastic recovery) are determined and compared with rutting.

Abstrakt ve sborníku z mezinár. konf.

2018, Silniční obzor, 79 (2), p. 31-35), ISSN 0322-7154

V současné době existuje řada metodik, jak popsat vlastnosti asfaltového pojiva. Autoři porovnávají empirické zkoušky penetrace a bodu měknutí se zkouškami funkčními, prováděnými na dynamickém smykovém reometru. jedná se o měření fyzikálních vlastností a dle posledních navržených postupů i zjištění odolnosti proti stárnutí asfaltového pojiva. Cílem práce je provedení korelací na 12 vzorcích modifikovaných asfaltů připravených z různých polymerů.

Článek v odborném recenzovaném periodiku česky

2018, Canadian Technical Asphalt Association Proceedings 2018, West Kelowna, Canadian Technical Asphalt Association), p. 79-98), ISBN 978-0-9869141-7-1

The rutting resistances of eleven modified polymers and one conventional asphalt binder were investigated in this study. All binders studied were modified to obtain a similar performance grade level of close to PG 64-xx. Multiple stress creep recovery tests were conducted on these binders at three different temperatures (50 °C, 60 °C, and 70 °C) and at five different shear stress loadings (0.1 kPa, 3.2 kPa, 6.4 kPa, 12.8 kPa, 25.6 kPa). To investigate which MSCR stress level correlates best with the asphalt binder’s high temperature properties, MSCR test results were compared with the Hamburg wheel-track testing results that were obtained at 60 °C.

Stať ve sborníku z mezinár. konf.

2018, Silniční obzor, 79 (9), p. 253-260), ISSN 0322-7154

Předpokladem udržitelného rozvoje při stavbě asfaltových vozovek je adekvátní plánování konstrukce silnic a dálnic. Vlastnosti jednotlivých vrstev vozovky musí odpovídat intenzitě dopravy dané silnice. Proto je znalost fundamentálních vlastností všech součástí asfaltových směsí, z nichž se vozovka skládá, nedílnou součástí plánování. V současné době existuje řada metodik, jak popsat vlastnosti asfaltového pojiva. Průměrná nevratná deformace po smykovém dotvarování při opakovaném zatížení je stanovena při třech teplotách (50 °C, 60 °C, 70 °C) a pěti různých smykových napětích (0,1 kPa, 3,2 kPa, 6,4 kPa, 12,8 kPa, 25,6 kPa) na devíti modifikovaných a na jednom základním asfaltu s přibližně stejnou horní kritickou teplotou 64 °C (dle parametru ǀG*ǀ/sinδ). Vedle funkčních zkoušek, provedených při vyšších zatíženích, jsou stanoveny i nejdůležitější empirické vlastnosti asfaltových pojiv: penetrace, bod měknutí a vratná duktilita. Na asfaltových směsích, vyrobených ze zkoušených asfaltových pojiv, je provedena zkouška pojíždění kolem, jejíž výsledky jsou následně porovnány s výsledky zkoušení asfaltových pojiv. Cílem práce je provedení korelací mezi fyzikálními vlastnostmi asfaltových pojiv, určených při vysokých smykových zatíženích, a odolnosti asfaltových směsí proti vyjíždění kolejí.

Článek v odborném recenzovaném periodiku česky

2015, Proceedings of the 3rd Annual International Conference on Architecture and Civil Engineering, Singapore, Global Science & Technology Forum (GSTF)), p. 203-210), ISSN 2301-394X

The paper discusses asphalt mixture design, its laboratory evaluation and highway pavement design methodologies used in Europe and the United States of America, California, with regard to fatigue resistance potential. A critique of several common practices, followed by recommendations based on the latest research findings and their relation to pavement field performance are included in the Introduction chapter. The paper presents particular data of fatigue resistance behavior measured on asphalt mixtures with various types of bituminous binder (neat, chemically modified and polymer-modified asphalt binders). These data demonstrate the differences between 50 % loss modulus standard procedure and dissipated energy concept. Moreover, the variability of asphalt mixture fatigue resistance and the stochastic method for calculation of proportional coefficient as one of the pavement design parameters are presented. The implementation of such an approach may be used into a pavement design methodologies.

Stať ve sborníku z mezinár. konf.

2015, Applied Rheology, 25 (3), p. 1-8), ISSN 1617-8106

The creep and recovery of asphalt modified with Elvaloy 4170 and polyphosphoric acid were studied at low temperatures, by inductive phenomenological methods. Two models of the tensile compliance function were investigated. Both models were derived from the linear viscoelastic retardation spectra and successfully used for the description of the creep and recovery tests in the studied asphalt binders. Large effects due to oxidative aging in a rolling thin film oven were found from the recovered compliance function recorded in a bending beam rheometer at a temperature of - 20°C. The studied compliance function models worked well at higher and lower temperatures in creep and recovery experiments on conventional and modified asphalt binders for both shear and tensile creep.

Článek v periodiku excerpovaném SCI Expanded

2015, Fuel Processing Technology, 140, p. 172-179), ISSN 1873-7188

The impacts of two different groups of polymers on the mechanical and rheological properties in a hard base asphalt were investigated. One group was modified with a reactive polymer, Elvaloy® 4170, with or without polyphosphoric acid (PPA). The other group used in this studywas styrene butadiene styrene (SBS) D1101, either crosslinked with sulfur or not. The rheological properties of these materials were investigated by smallamplitude oscillations and steady-state shear viscosity. It was shown that the properties of a polymer modified asphalt blends beside depending on the type of polymer are strongly dependent on the presence of PPA and sulfur as it was clearly manifested in dynamic experiments. Steady state shear viscosity measured at 60 °C showed a possible chemical interaction between Elvaloy and PPA. The blends with SBS D1101 (at the same temperature) showed a more complicated behavior.

Článek v periodiku excerpovaném SCI Expanded

2014

Tato diplomová práce se hlavně zabývá novými metodami zkoumání reologických vlastností asfaltů při vysokých teplotách. Jejím cílem je srovnání reologických vlastností čtyř asfaltů, z nichţ tři jsou modifikované různými polymery s odlišnými koncentracemi. Součástí práce je i stanovení bodu měknutí všech asfaltů pomocí empirické zkoušky krouţek a kulička. Všechny jejich vlastnosti jsou stanoveny před i po stárnutí, kde samotné stárnutí je provedena metodou RTFOT. Zabývá se také problematikou měření reologických vlastností modifikovaných asfaltů. V závěru práce je vyhodnocena pravděpodobnost vlivu zkoumaných asfaltů na vlastnosti z nich vyrobených asfaltových směsí.

Diplomová práce

2013

Pro zkoumání vhodnosti využití daných technologií pro modernizaci D1 byla zvolena kvantitativní metoda analýza SAFMEA a velká skupina respondentů

Výzkumná zpráva v češtině

2011, Silniční obzor, 72 (2), p. 31-36), ISSN 0322-7154

Článek se zabývá popisem a numerickou simulací zkoušky pojíždění kolem. Pro testování je zvolen typ kanadské konvenčně používané asfaltové hutněné směsi do obrusných vrstev Lafarge 12.5. Článek se zabývá zatížením a popisem zkoušených materiálů při zkoušce pojíždění kolem a teoretickými metodami pro simulaci asfaltových hutněných směsí.

Článek v periodiku z pozitivního seznamu RVVI česky

2010, Road and Rail Infrastructure, Zagreb, University of Zagreb, Faculty of Civil Engineering), p. 283-289), ISBN 978-953-6272-38-9

In this paper two different methodologies have been adopted and compared performing tests on selected asphalt concretes (AC's), called two point bending (2PB-TR) and four point bending (4PB-PB) using trapezoidal and prismatic beams respectively. Even though methodologies of these tests are known for some time interpretation of results according to the EU 12697-26 standard is rather unclear. Stiffness moduli are being compared at different temperatures, which were found unnecessary. Paper describes influence of different loadings and temperatures on selected asphalt concretes.

Stať ve sborníku z mezinár. konf.

2010, Pozemní komunikace 2010, Praha, České vysoké učení technické v Praze, Fakulta stavební), p. 100-108), ISBN 978-80-01-04582-4

Článek je zaměřen na výčet odchylek získaných z měření modulů tuhosti metodou čtyřbodového ohybu. Pro praktické posouzení získaných hodnot jsou data doplněna o porovnání s odchylkami získanými z měření metodou příčného tahu.

Stať ve sborníku z lokální konf. česky

2009, Silniční obzor, 70 (6), p. 135-138), ISSN 0322-7154

Článek se zabývá posouzením zkoušky pojíždění kolem v podmínkách České Republiky. Asfaltové směsi typu konvenčního asfaltového betonu (ACO) a asfaltového koberce mastixového (SMA) jsou posuzovány z hlediska trvalých deformací při teplotách 50 a 60°C. Dále je hodnocen vliv modifikovaného pojiva na asfaltvé hutněné směsi.

Článek v periodiku z pozitivního seznamu RVVI česky

2009, Silnice železnice, 4 (1), p. 21-22), ISSN 1801-822X

V posledních několika letech dochází v České republice, stejně tak jako v ostatních státech Evropy, k postupnému sjednocování norem. Výsledkem je vytváření anebo přejímání nových specifikací z ostatních členských států. Cílem každé specifikace je co možná nejpřesnější vystižení dané problematiky, což může být z hlediska funkčního posouzení materiálů dlouhodobý proces. V tomto příspěvku je posuzována norma hodnocení vlastností litých asfaltů. Dynamické zkoušky byly prováděny ve dvou nezávislých laboratořích. Příspěvek se zabývá dosaženými výsledky, které byly zpracovány v souladu s předepsanou normou. Cílem je přispět k efektivnějšímu posouzení litých asfaltů.

Článek v periodiku z pozitivního seznamu RVVI česky

2008, ISBN 978-80-01-04071-3

Asphalt binders are rheologicaly complex materials that exhibit viscous flow, elastic recovery and or plastic deformations at various temperatures. Because of its viscoelastic nature, asphalt behavior depends on both temperature and time of loading, these two are related. The behavior at high temperature over a short period is equivalent to what occurs at lower temperatures over long durations. This is often referred as time-temperature shift or superposition concept of asphalt. Unfortunately, universal constitutive equations have not been developed yet for these materials. Rheological description of asphalt binders is rather empirical and is more less based on extensive material testing, providing hypothesis applied in practice. North American Performance Grade (PG) specifications are introduced and possibility of the 2nd and the 3rd generation of European standards are discussed.

Habilitační přednáška

2007, Advanced Characterisation of Pavement and Soil Engineering Materials, London, Tailor & Francis Group), p. 843-851), ISBN 978-0-415-44882-6

The present strategies and trends in road pavement technologies focus increasingly on sustainable solutions emphasizing the necessity of natural resources preservation and increase in use of recyclable and secondary materials as well as reduction of energy consumption, which results in lower concentration of emissions. There are several technologies used European wide for asphalt pavements and classified as cold or warm techniques. Most of them are based on bituminous emulsions or foam bitumen process. In Czech Republic the progress in using cold recycling technologies started approximately ten years ago utilizing especially the combination of bituminous emulsion and hydraulic binders applied as in-place technique for pavement sub-base rehabilitation.

Stať ve sborníku z mezinár. konf.

2007, Advanced Characterization of Pavement and Soil Engineering Materials, London, Tailor & Francis Group), p. 843-851), ISBN 978-0-415-44880-2

The present strategies and trends in road pavement technologies focus increasingly on sustainable solutions emphasizing the necessity of natural resources preservation and increase in use of recyclable and secondary materials as well as reduction of energy consumption, which results in lower concentration of emissions. There are several technologies used European wide for asphalt pavements and classified as cold or warm techniques. Most of them are based on bituminous emulsions or foam bitumen process. In Czech Republic the progress in using cold recycling technologies started approximately ten years ago utilizing especially the combination of bituminous emulsion and hydraulic binders applied as in-place technique for pavement sub-base rehabilitation.

Stať ve sborníku z mezinár. konf.

2007, Complex System of Methods for Directed Design and Assessment of Functional Properties of Building Materials, Praha, ČVUT v Praze, FSv), p. 33-36), ISBN 978-80-01-03929-8

Durability of Portland concrete is one of the most fundamental parameters, which define the ability of material to resist series of freezing-thawing cycles by parallel effect of chemical defrosting resistance. Generally, it is believed that the material is compact without micro cracks and opened pores. However, this does not reflex the reliability. By adding metakaolin which granulometry is properly design; it is possible to achieve improvement of compactness of material and decreasing of volume of pores in it. This article deals with experimental determination of surface waste amount for two different types of concrete, which depends on number of freezing-thawing cycles in saline solution.

Stať ve sborníku z mezinár. konf. cizojazyčně

2007, The Influence of Accelerated Curing on Cold In-Place Recycling, Laval, Polyscience Publications Inc.), p. 215-235), ISBN 0-921317-61-1

This work is a continuation of the SCORE research program, which was dedicated to cold recycling using asphalt emulsions. The goal here was to investigate curing time and conditions at elevated temperatures and lower humidity in order to predict material behaviour after several years in service. A comparative test program was conducted among Eurovia Services and Czech Technical University laboratories with the emphasis of curing practices that would lead to the improvement of mechanical properties.

Stať ve sborníku z mezinár. konf.

2006, The 10th East Asia-Pacific Conference on Structural Engineering & Construction - Materials, Experimentation, Maintenance and Rehabilitation, Bangkok, Asian Institute of Technology), p. 335-340), ISBN 974-8257-18-5

In general, the stress distribution in asphalt pavement is significantly influenced by the adhesion conditions at the interface between the asphalt layers. To increase bonding between layers, some highway agencies apply tack coats to improve the adhesion between layers. In spite of their wide application, the opinions among pavement engineers differ regarding the effectiveness of different tack coat materials in enhancing the adhesion between two asphalt layers.

Stať ve sborníku z mezinár. konf.

2006, Proceedings of the Fourth International Scientic Conference "Challenges in Transport and Communication", Pardubice, Univerzita Pardubice), p. 879-883), ISBN 80-7194-880-2

Neustálý nárůst cen energií vede výrobní podniky k hledání možností snižování nákladů výroby asfaltových směsí a to i formou využití alternativních topných médií. Tato změna se však nemusí vždy setkat s principem technologie výrobku. Je nutné provést laboratorní ověření pro stanovení možného využití alternativního topného média. Článek popisuje možné využití uhelného multiprachu jako dalšího zdroje pro vytápění obalovny. V rámci prací byla provedena srovnání vybraných vlastností asfaltové směsi typu ABVH. Byly srovnávány směsi, které byly vyrobeny při ohřevu plynem a při ohřevu uhelným mourem.

Stať ve sborníku z lokální konf. česky

2005, Asfaltové vozovky 2005, Praha, Sdružení pro výstavbu silnic), p. 76-80), ISBN 80-903279-1-5

Příspěvek porovnává mechanické vlastnosti asfaltového pojiva s vlastnostmi hutněných asfaltových směsí. Na všechny testované materiály se aplikovala teorie lineární vaskopružnosti, přičemž byl v dynamickém modu zjišťován smykový modul G*, spočítán komplexní modul vztažený k hodnotě dotvarování J(t).

Stať ve sborníku z lokální konf. česky

2005, Asfaltové vozovky 2005, Praha, Sdružení pro výstavbu silnic), p. 215-219), ISBN 80-903279-1-5

První snahy o popis asfaltových materiálů na základě vztahu zatížení - přetvoření sahá do pooloviny minulého století. Tento fenomén může být sledován na základě vědního oboru reologie, která se zabývá tečením všech látek. Na konci osmdesátých let bylo proveden nový výzkum v rámci programu Strategic Highway Research Program (SHRP). V tomto programu byly kromě jiného sledovány v závislosti na teplotě vlastnosti asfaltových pojiv, především smykový dynamický modul stanovený cyklickou oscilací.

Stať ve sborníku z lokální konf. česky

2003, Transportation Research Record (1829), p. 33-38), ISSN 0361-1981

The possibility of using commercial rheometers for comprehensive testing of asphalt binders, asphalt mastics, and hot-mix asphalts (HMA) is explored. Samples of one polymer-modified asphalt, its mix with fine mineral filler (mastic), and one HMA prepared with the same modified asphalt as binders were tested in the dynamic shear rheometer (DSR) and the bending beam rheometer (BBR). All tested materials can be characterized by their discrete relaxation and retardation spectra (under the condition of small deformations). DSR testing was performed in the plate-plate and the torsion bar geometry. From the obtained relaxation and retardation spectra, the shear compliance, J(t), was calculated and compared with the tensile creep compliance, D(t), measured in BBR (both creep and recovery experiments were run). A simple relationship between J(t) and D(t) was found for the asphalt binder and the asphalt mastic. In the case of HMA, the bulk compliance, B(t), contributes to D(t) at short and long times. Both the Boltzmann superposition principle and the time-temperature superposition principle hold very well for all tested materials at low temperatures. There are qualitative differences, in the rheological behavior, of the asphalt binder and asphalt mastic on one side and the HMA on the other. These differences can be seen in dynamic (DSR) as well as in transient (BBR) experiment

Článek v periodiku excerpovaném SCI Expanded

2003, Applied Rheology, 3 (13), p. 118-124), ISSN 1617-8106

Polymer modified asphalt is an highly temperature sensitive material. To obtain the master curves of dynamic material functions, for this material, it is necessary to perform the testing over the temperature interval from - 30°C to at least 90°C. Since in this temperature range the polymer modified asphalt undergoes the transition from a glass-like to a Newtonian-like material, the benefit of using three testing geometries is studied here. The geometries used were: torsion bar (for the low temperatures), plate-plate (for the mid range temperatures) and bob and cup (for the high temperatures). The advantage of the combination of these three geometries is discussed. Stress and strain controlled rheometers were used to conduct all dynamic experiments. Master curves obtained by these geometries cover Up to 20 decades of the reduced frequency.

Článek v periodiku excerpovaném databází Scopus

2003, JOURNAL OF COLLOID AND INTERFACE SCIENCE, 259 (1), p. 200-207), ISSN 0021-9797

Asphalt is a multidisperse micellar system with rheological behavior resembling that of a low-molecular-weight polymer. Nowadays, asphalt is frequently modified by blending it with various polymers. Such modified asphalt has rheological properties that differ from the properties of the base asphalt. It is quite common to study asphalt in dynamic experiments. Such studies, however useful, cannot reveal all characteristic features of polymer-modified asphalts. Asphalt modification by polymers is strongly manifested in the region of transitions from a viscoelastic fluid to the Newtonian fluid. The viscosity study in this region can reveal behavior characteristic of the used polymer modifier, thus complementing the dynamic studies of these materials. The viscosity of base asphalt modified by styrene-butadiene-styrene and by ethylene-vinyl acetate polymers (in several concentrations) is studied and discussed in this note.

Článek v periodiku excerpovaném SCI Expanded

2000, Transportation Research Record, 2000 (1728), p. 15-20), ISSN 0361-1981

Shear vibrations in conventional and polymer-modified asphalt binders are examined. Using dynamic compliances instead of moduli, viscous deformation effects can be separated from total deformation and the modified dynamic loss compliance and modified loss tangent functions can be defined. These two material functions appear to be more sensitive than viscoelastic moduli to the rheological behavior of asphalt binders and to changes caused by polymer addition. The characteristic temperature of the transition from the viscoelastic to viscous behavior of asphalt binder (Tv) can be identified by using the viscous asymptote J". The damping of shear vibrations that likely relates to the internal structure of asphalt material can be described by the modified loss tangent. The rheological behavior of the base asphalt 200/300 penetration grade and its blends with different amounts of radial styrene-butadiene-styrene rubber is investigated. Using master curves of dynamic functions and the Williams-Landel-Ferry form of the shift factor, isochrones of the original and modified dynamic material functions are constructed. Characteristic temperatures of the viscous transition (Tv) and the glass transition (Tg) are determined. Damping behaviors of the base and modified asphalts are studied.

Článek v periodiku excerpovaném SCI Expanded

2000, Applied Rheology, 10 (4), p. 185-191), ISSN 1617-8106

Costly deterioration of many roads and highways paved with asphalt generates a growing interest in polymer modified asphalts (PMA). Although asphalt represents only a fraction of asphalt paving mix, it is believed that it has a significant effect on the thermomechanical properties of asphalt pavements. Currently there is no consensus on the type of tests and specifications for polymer modified asphalts; however, it is clear that such specifications should be based on rheological testing of these systems. As a viscoelastic material asphalt is usually characterized by its dynamic material functions. An advantage of the use of modified loss tangent function in PMA systems is discussed in this contribution. Three polymer modifiers (SBS, EVA and EGA) commonly used in the asphalt paving industry were blended with base asphalt and various relaxations in the base, and its blends are studied here.

Článek v periodiku excerpovaném databází Scopus