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Papers by Svatopluk Stoklasek

Engineering Solid Mechanics, 2020

Mastic mortar, i.e. a mixture of bitumen and very fine filler particles (i.e. aggregate fine part... more Mastic mortar, i.e. a mixture of bitumen and very fine filler particles (i.e. aggregate fine particles smaller than 0.063 mm), can significantly co-influence not only rheological properties of the processed asphalt mixture, but also the visco-elastic properties of compacted asphalt layers including resistance against crack formation. Nevertheless, the number of scientific studies dedicated to this topic in detail, is very limited. The aim of this work is to determine the basic rheological properties of these mastic materials using a dynamic shear rheometer, in particular concentrating on the petrographic origin of the filler particles. Fourteen filler types were selected and mixed with paving bitumen 70/100 in various ratios. Petrographic composition of the individual fillers was determined using powder X-ray diffraction analysis. Attention was given especially to the effect of the presence of mica on the filler and mastic properties. Filler properties were analyzed using the voids of dry compacted filler test so-called "Rigden voids" and the delta ring and ball test. Mastic mortars prepared in a laboratory were subjected to multiple stress creep and recovery test and oscillation measured at 60 °C in a dynamic shear rheometer. Results show that using dynamic shear rheometer to determine the properties of these materials is advantageous. Petrographic origin of the filler to a great extent affects the behavior and properties of the mastic mortar, especially its stiffening effect. Limestone filler stiffened the bituminous binder the least and reference materials, containing high ratio of mica, stiffened the binder the most.

Road Materials and Pavement Design, 2017

Some bituminous binders currently available on the Central European market contain a certain rati... more Some bituminous binders currently available on the Central European market contain a certain ratio of visbreaking residues, obtained during non-catalytic thermal cracking of atmospheric or vacuum crude oil residues. This paper deals with a potential presence of visbreaking residues in commercially available paving grade bitumens, and their impact on the thermooxidative properties of the bitumen. The presence of visbreaking residues can be possibly indicated by the compromised chemical compatibility of the bituminous binder that can be determined by Heithaus titration. However, Heithaus titration is a relatively complicated process. It is therefore sufficient to use a simplified alternative in practice-single-point precipitation titration using isooctane. All of the tested bitumens were submitted to the accelerated ageing procedure. The changes in parameters caused by the ageing process were determined by means of a dynamic shear rheometer and bending beam rheometer. The obtained data were subsequently compared with the results from laboratory prepared binders, which contained a known portion of visbreaking residues. The content of visbreaking residues in these binders ranged from 0% to 40%. The results showed that the presence of visbreaking residues has a negative impact on the properties of paving bitumens, especially with respect to their thermooxidative ageing. Particularly, the modified method of accelerated ageing RTFOT with an extended exposition time can differentiate between the individual binders very well, and is able to correlate their properties to the content of visbreaking residues. As the content of these residues increases, the extent of change increases proportionally for the analysed parameters describing the properties of the binders in middle and elevated service temperatures. The results of the analysis suggest that the disrupted chemical compatibility proved by single-point precipitation titration using isooctane may indicate a thermooxidatively unstable bitumen, and that this fact might be related to a higher content of visbreaking residues.

International Journal on Pavement Engineering & Asphalt Technology, 2015

The Asphalt pavements in Central and Eastern Europe have to be resistant to high and very low tem... more The Asphalt pavements in Central and Eastern Europe have to be resistant to high and very low temperatures and climatic changes. Especially emphasize influence of low temperatures seems to be critical parameter. That is why the modified bitumens with low temperature susceptibility and with high resistance to low temperature cracking are searched for. Dynamic Shear Rheometer (DSR) can be used as a quick method that can evaluate the modification system of bituminous binders. The advantage of DSR testing is also related to possibility of comparison of unaged and aged bitumen. The relaxations of shear stress of several asphalt rubber binders (containing 11 %, 13 %, 15 % and 17 % of crumb rubber) and paving bitumen were determined in DSR at the temperature of 0 °C and −10 °C. Relaxation tests were performed in the controlled strain regime. Total shear strain (rotation of upper geometry) was set to 1 % of the sample thickness and stress was applied for 60 s. Relaxation time was set to a p...

Zeitschrift f�r anorganische und allgemeine Chemie, 1987

ABSTRACT Durch Umsetzung von Phenylthiophosphonsäuredichlorid PhP(S)Cl2 (1) mit Hexamethyldisilaz... more ABSTRACT Durch Umsetzung von Phenylthiophosphonsäuredichlorid PhP(S)Cl2 (1) mit Hexamethyldisilazan (HMDSA) wurde das Bis(trimethylsilylamid) dieser Säure PhP(S)(NHSiMe3)2 (2) hergestellt und durch thermische Zersetzung von 2 das 1,3-Bis(trimethyl-silyl)-2,4-diphenyl-2,4-dithioxo-1,3,2λ5,4λ5-diazadiphosphetid [PhP(S)NSiMe3]2 (3) erhalten. Mit Hilfe von Massen-, IR-, Raman- und NMR (1H, 31P, 13C, 29Si)-Spektren wurde die Struktur der in hoher Reinheit isolierten Verbindungen 2 und trans-3 aufgeklärt. NMR-spektroskopisch konnten die ersten Hydrolysestufen beider Verbindungen nachgewiesen werden. Neben dem vorwiegend entstehenden trans-Isomer von 3 wird zu etwa 10% das cis-Isomer gebildet.Synthesis, Properties, and N.M.R. Investigation of Phenylphosphonothioic Acid Bis-(trimethylsilylamide) and 1,3-Bis(trimethylsilyl)-2,4-diphenyl-2,4-dithioxo-1,3,2λ5,4λ5-diazadiphosphetidineThe reaction of phenylphosphonothioic dichloride PhP(S)Cl2 (1) with hexamethyl-disilazane (HMDSA) yields N,N′-bis(trimethylsilylamide) of phenylphosphonothioic acid PhP(S)(NHSiMe3)2 (2). The thermolysis of 2 leads to the 1,3-bis(trimethylsilyl)-2,4-diphenyl-2,4-dithioxo-1,3,2λ5, 4λ5-diazadiphosphetidine [PhP(S)NSiMe3]2 (3). The structures of the compounds 2 and trans-3 isolated in high purity habe been elucidated by means of mass, IR-, Raman-, and NMR (1H, 31P, 13C, 29Si) spectra. The first hydrolysis products of both compounds have been proved by NMR spectroscopy. Besides the predominantly formed trans-isomer of 3 the corresponding cis-isomer is obtained with 10% yield.

Key Engineering Materials, 2020

The paper deals with the influence of geosynthetic reinforcement systems on the quality of asphal... more The paper deals with the influence of geosynthetic reinforcement systems on the quality of asphalt bonding layers. A reinforcing element in the form of a fiberglass grid is incorporated into the road structure between two asphalt layers to prevent the formation of cracks and to reduce the tendency of their subsequent propagation throughout the asphalt layers. At the same time, however, they form a potential weak interlayer on which adjacent asphalt layers may slip. The total 90 drilled cores taken from a laboratory-produced two-layer slabs were subjected to the Leutner shear test. The selection of individual specimens took into account both the type of reinforcement element and the amount of applied bituminous emulsion.

3rd Annual International Conference on Architecture and Civil Engineering (ACE 2015), 2015

The paper discusses asphalt mixture design, its laboratory evaluation and highway pavement design... more 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.

Engineering Solid Mechanics, 2020

Mastic mortar, i.e. a mixture of bitumen and very fine filler particles (i.e. aggregate fine part... more Mastic mortar, i.e. a mixture of bitumen and very fine filler particles (i.e. aggregate fine particles smaller than 0.063 mm), can significantly co-influence not only rheological properties of the processed asphalt mixture, but also the visco-elastic properties of compacted asphalt layers including resistance against crack formation. Nevertheless, the number of scientific studies dedicated to this topic in detail, is very limited. The aim of this work is to determine the basic rheological properties of these mastic materials using a dynamic shear rheometer, in particular concentrating on the petrographic origin of the filler particles. Fourteen filler types were selected and mixed with paving bitumen 70/100 in various ratios. Petrographic composition of the individual fillers was determined using powder X-ray diffraction analysis. Attention was given especially to the effect of the presence of mica on the filler and mastic properties. Filler properties were analyzed using the voids of dry compacted filler test so-called "Rigden voids" and the delta ring and ball test. Mastic mortars prepared in a laboratory were subjected to multiple stress creep and recovery test and oscillation measured at 60 °C in a dynamic shear rheometer. Results show that using dynamic shear rheometer to determine the properties of these materials is advantageous. Petrographic origin of the filler to a great extent affects the behavior and properties of the mastic mortar, especially its stiffening effect. Limestone filler stiffened the bituminous binder the least and reference materials, containing high ratio of mica, stiffened the binder the most.

Road Materials and Pavement Design, 2017

Some bituminous binders currently available on the Central European market contain a certain rati... more Some bituminous binders currently available on the Central European market contain a certain ratio of visbreaking residues, obtained during non-catalytic thermal cracking of atmospheric or vacuum crude oil residues. This paper deals with a potential presence of visbreaking residues in commercially available paving grade bitumens, and their impact on the thermooxidative properties of the bitumen. The presence of visbreaking residues can be possibly indicated by the compromised chemical compatibility of the bituminous binder that can be determined by Heithaus titration. However, Heithaus titration is a relatively complicated process. It is therefore sufficient to use a simplified alternative in practice-single-point precipitation titration using isooctane. All of the tested bitumens were submitted to the accelerated ageing procedure. The changes in parameters caused by the ageing process were determined by means of a dynamic shear rheometer and bending beam rheometer. The obtained data were subsequently compared with the results from laboratory prepared binders, which contained a known portion of visbreaking residues. The content of visbreaking residues in these binders ranged from 0% to 40%. The results showed that the presence of visbreaking residues has a negative impact on the properties of paving bitumens, especially with respect to their thermooxidative ageing. Particularly, the modified method of accelerated ageing RTFOT with an extended exposition time can differentiate between the individual binders very well, and is able to correlate their properties to the content of visbreaking residues. As the content of these residues increases, the extent of change increases proportionally for the analysed parameters describing the properties of the binders in middle and elevated service temperatures. The results of the analysis suggest that the disrupted chemical compatibility proved by single-point precipitation titration using isooctane may indicate a thermooxidatively unstable bitumen, and that this fact might be related to a higher content of visbreaking residues.

International Journal on Pavement Engineering & Asphalt Technology, 2015

The Asphalt pavements in Central and Eastern Europe have to be resistant to high and very low tem... more The Asphalt pavements in Central and Eastern Europe have to be resistant to high and very low temperatures and climatic changes. Especially emphasize influence of low temperatures seems to be critical parameter. That is why the modified bitumens with low temperature susceptibility and with high resistance to low temperature cracking are searched for. Dynamic Shear Rheometer (DSR) can be used as a quick method that can evaluate the modification system of bituminous binders. The advantage of DSR testing is also related to possibility of comparison of unaged and aged bitumen. The relaxations of shear stress of several asphalt rubber binders (containing 11 %, 13 %, 15 % and 17 % of crumb rubber) and paving bitumen were determined in DSR at the temperature of 0 °C and −10 °C. Relaxation tests were performed in the controlled strain regime. Total shear strain (rotation of upper geometry) was set to 1 % of the sample thickness and stress was applied for 60 s. Relaxation time was set to a p...

Zeitschrift f�r anorganische und allgemeine Chemie, 1987

ABSTRACT Durch Umsetzung von Phenylthiophosphonsäuredichlorid PhP(S)Cl2 (1) mit Hexamethyldisilaz... more ABSTRACT Durch Umsetzung von Phenylthiophosphonsäuredichlorid PhP(S)Cl2 (1) mit Hexamethyldisilazan (HMDSA) wurde das Bis(trimethylsilylamid) dieser Säure PhP(S)(NHSiMe3)2 (2) hergestellt und durch thermische Zersetzung von 2 das 1,3-Bis(trimethyl-silyl)-2,4-diphenyl-2,4-dithioxo-1,3,2λ5,4λ5-diazadiphosphetid [PhP(S)NSiMe3]2 (3) erhalten. Mit Hilfe von Massen-, IR-, Raman- und NMR (1H, 31P, 13C, 29Si)-Spektren wurde die Struktur der in hoher Reinheit isolierten Verbindungen 2 und trans-3 aufgeklärt. NMR-spektroskopisch konnten die ersten Hydrolysestufen beider Verbindungen nachgewiesen werden. Neben dem vorwiegend entstehenden trans-Isomer von 3 wird zu etwa 10% das cis-Isomer gebildet.Synthesis, Properties, and N.M.R. Investigation of Phenylphosphonothioic Acid Bis-(trimethylsilylamide) and 1,3-Bis(trimethylsilyl)-2,4-diphenyl-2,4-dithioxo-1,3,2λ5,4λ5-diazadiphosphetidineThe reaction of phenylphosphonothioic dichloride PhP(S)Cl2 (1) with hexamethyl-disilazane (HMDSA) yields N,N′-bis(trimethylsilylamide) of phenylphosphonothioic acid PhP(S)(NHSiMe3)2 (2). The thermolysis of 2 leads to the 1,3-bis(trimethylsilyl)-2,4-diphenyl-2,4-dithioxo-1,3,2λ5, 4λ5-diazadiphosphetidine [PhP(S)NSiMe3]2 (3). The structures of the compounds 2 and trans-3 isolated in high purity habe been elucidated by means of mass, IR-, Raman-, and NMR (1H, 31P, 13C, 29Si) spectra. The first hydrolysis products of both compounds have been proved by NMR spectroscopy. Besides the predominantly formed trans-isomer of 3 the corresponding cis-isomer is obtained with 10% yield.

Key Engineering Materials, 2020

The paper deals with the influence of geosynthetic reinforcement systems on the quality of asphal... more The paper deals with the influence of geosynthetic reinforcement systems on the quality of asphalt bonding layers. A reinforcing element in the form of a fiberglass grid is incorporated into the road structure between two asphalt layers to prevent the formation of cracks and to reduce the tendency of their subsequent propagation throughout the asphalt layers. At the same time, however, they form a potential weak interlayer on which adjacent asphalt layers may slip. The total 90 drilled cores taken from a laboratory-produced two-layer slabs were subjected to the Leutner shear test. The selection of individual specimens took into account both the type of reinforcement element and the amount of applied bituminous emulsion.

3rd Annual International Conference on Architecture and Civil Engineering (ACE 2015), 2015

The paper discusses asphalt mixture design, its laboratory evaluation and highway pavement design... more 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.