Bitumen Characterization with Fourier Transform Infrared

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Bitumen characterization with FTIR spectroscopy and multivariate evaluation: Prediction of various physical and chemical parameters Sandra Weigel, and Dietmar Stephan Energy Fuels, Just Accepted Manuscript • DOI: 10.1021/acs.energyfuels.8b02096 • Publication Date (Web): 11 Sep 2018 Downloaded from http://pubs.acs.org on September 12, 2018

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Bitumen characterization with FTIR spectroscopy and multivariate evaluation: Prediction of various physical and chemical parameters Sandra Weigel, Dietmar Stephan Technische Universität Berlin – Building Materials and Construction Chemistry Gustav-Meyer-Allee 25, 13355 Berlin, Germany

KEYWORDS bitumen, FTIR, Partial Least Square Regression, prediction physical parameters, prediction chemical parameters

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ABSTRACT

As the aim of this work, the characterization of bitumen based on the Fourier transform infrared (FTIR) spectroscopy combined with the multivariate evaluation was investigated. For this, 90 bitumen samples were analyzed using the attenuated total reflection technology with multiple reflections. The gained spectra were divided into two partial spectra with the relevant peaks and pre-processed with a Standard Normal Variate transformation and the first derivative. For a comprehensive evaluation, a multivariate analysis method in terms of the Partial Least Square Regression was used. Based on this procedure, models could be determined allowing the description and prediction of different bitumen parameters including the penetration, the complex shear modulus, the phase angle and the asphaltene content. Further, the softening point can be estimated roughly. In contrast, the description of the flexural stiffness a well as the m value capturing the low-temperature behavior and the description of the content of the different maltene fractions are not possible. Concerning the structural relationships, increasing hardness, viscosity, stiffness and elastic behavior are associated with an increase of the aromatic and oxygen-containing compounds and changes in the structure of the aromatics and alkenes.


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1. INTRODUCTION Bitumen is a building material with a complex physico-mechanical behavior caused by the very complex chemical composition and structure. The bitumen consists of a large number of different compounds which cannot be identified in detail. To get information about the structure of bitumen nonetheless, the Fourier transform infrared (FTIR) spectroscopy is a suitable method. The FTIR spectroscopy is based on interactions between infrared radiation and the molecules in a sample. The molecules absorb parts of the infrared radiation and, thus, are stimulated to vibrate. Thereby, the intensity and the wavelength of the absorbed radiation depend on the present compounds and allow conclusions about the molecules or rather molecule components in the considered sample. For the analysis of bitumen, the FTIR spectroscopy is mainly used to evaluate the aging behavior of the binder considering the oxygen-containing compounds in terms of the carbonyls and the sulfoxides.1-13 However, different studies demonstrated that the FTIR spectra of crude oil based products contain considerably more information about the product properties.14-16 This information could be gained with multivariate analysis methods allowing a comprehensive evaluation of the spectra. For example, different parameters of crude oil residues can be captured with the FTIR spectra of the crude oils including its proportion, the density, viscosity as well as the content of asphaltenes and sulfur.14 In own previous studies, the evaluation of the FTIR spectra with multivariate analysis methods was transferred to bitumen. It could be randomly shown for a small number of samples that the FTIR spectra of bitumen allow the differentiation according to the refinery as well as the estimation of different physical parameters including the penetration, softening point, complex shear modulus and the phase angle.16 In the present work, the description and prediction of different physical and chemical bitumen parameters based on the FTIR spectra are deepened whereby, on the one hand, the


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models are verified with a larger data set. On the other hand, the evaluation of the FTIR spectra is extended by further parameters and the investigation of relationships between the structure and the parameters of bitumen.

2. MATERIALS AND METHODS As basis of this work, 36 paving grade bitumen samples of ten different refineries (A to J) and different crude sources were considered belonging to the grades 20/30, 30/45, 50/70 and 70/100 according to EN 12591. These samples exist in up to four different aging conditions whereby in total seven different aging states were considered. Beside the unaged condition, the aging states include the RFT (aging with Rotating Flask Test according to EN 12607-3), the single RTFOT (aging with Rolling Thin Film Oven Test according to EN 12607-1), the twice RTFOT, the three times RTFOT and the combined RFT and PAV as well as the combined RTFOT and PAV aged state (aging with the Pressure Ageing Vessel according to EN 14769). Due to the different aging states, in total 90 bitumen samples were considered in this work. However, the described samples came from various research projects. That is why, in part, different measurement methods were carried out to investigate the samples. Thus, for some test parameters, the 90 samples had to be divided into partial data sets. In each case, the samples were separated in calibration and validation data set according to Kessler16,

17

whereby the calibration data set

includes two thirds and the validation data set one third of the considered samples. For the Fourier transform infrared spectroscopy, the bitumen samples were solved with cyclohexane in a ratio of 1:3. The bitumen cyclohexane solution was applied on a zinc selenide crystal on which a bitumen film of on average 35 µm remained after the evaporation of the solvent (about 15 minutes). The analyses were carried out with the instrument Perkin Elmer


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Spectrum Two FT-IR 96108 allowing the attenuated total reflection (ATR) measurement with multiple reflections. For every sample, three single measurements were carried out considering 32 scans, a wave number range from 4,000 to 600 cm-1 and a resolution of 4 cm-1. The obtained reflectance spectra were converted in absorbance spectra whereby, for the further evaluation, only the relevant wave number ranges between 3,600 and 2,500 cm-1 as well as 1,800 and 690 cm-1 were considered. These two partial spectra were further pre-processed with a Standard Normal Variate (SNV) transformation as standardization based on the z transformation and the determination of the first derivative (according to Kessler17). These pre-processed partial spectra were the input data for the multivariate evaluation. Further, the areas of various spectra peaks were calculated to investigate the relationships between the structure and the different parameters of the bitumen. For the calculation, the SNV transformed spectra were used applying the integration from valley to valley according to the recommendation of van den Bergh.3 The peak areas were calculated for every single measurement before the mean value for every sample was determined. The vertical limits were defined with the spectra of the 90 bitumen samples and are shown in Figure 1. Concerning the aliphatic compounds, the symmetrical and asymmetrical stretching (ν) and bending (δ) vibrations of the methyl (CH3) and the methylene (CH2) group were considered. Further, the peak area of the bending deformation of the C-H bonds of the alkene compounds was calculated being an index for the structure of the alkenes. The second group includes the areas of the aromatic compounds with the stretching vibration of the aromatic C=C double bonds and three bending vibrations of the aromatic C-H bonds. These bending vibrations differ due to the number of hydrogen atoms between the substituents of the aromatic molecule and thus give information


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about the aromatic structure. Further, the oxygen-containing compounds include the stretching vibrations of the hydroxy, the carbonyl and the sulfoxide group.3, 4, 8, 18-20 The determination of the needle penetration PEN and the softening point ring and ball TR&B was carried out in two different laboratories according to EN 1426 and EN 1427. Further, the rheological properties were investigated by the Dynamic Shear Rheometer (DSR) according to EN 14770 and TL Bitumen-StB using the instrument Anton Paar Smartpave 102. Concerning the DSR investigations, two data sets exist which were generated in two different laboratories and are based on two different test methods summarized in Table 1. As results of the DSR measurements, the complex shear modulus |G*| and the phase angle δ were determined at the different temperature levels. According to EN 14771 and TL Bitumen-StB, investigations with the Bending Beam Rheometer were carried out in two different laboratories under the same conditions. With the instrument Coesfeld CBBR, the samples were analyzed on a temperature level of -16°C as well as for 8, 15, 30, 60, 120 and 240 seconds of loading. The obtained parameters of the BBR measurements are the flexural stiffness Sm and the m value. The asphaltene content wasphaltenes was determined according to DIN 51595 based on the extraction with n-heptane. Further, the content of the maltene fractions was investigated using the column chromatography according to Šebor et al.21. The used solvents and the obtained fractions are summarized in Table 2. For the multivariate evaluation of the FTIR spectra, the Partial Least Square Regression (PLSR) was used allowing the description of functional relationships between a dependent variable and various independent variables. The principle of the PSLR is a combination of a Principal Component Analysis (PCA) and a Multiple Linear Regression (MLR).17 Linear


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combinations as yphysical/ chemical = b0 + b1x1 + … + bjxj + … + bJxJ were established including the dependent variable y in terms of physical or chemical bitumen parameters, the regression coefficients bj and the independent variables xj in terms of the absorbance of all relevant wave numbers of the FTIR spectra. For the determination of the linear combination, at first, the PCA reduces the variables to the so-called PLSR components being then used as input data for the MLR.17 To avoid an overfitting of the models, the number of permitted PLSR components was limited to seven. For the evaluation of the determined linear combination, the coefficient of determination R² was established describing significant correlations with coefficients of R² ≥ 0.64 and weaker or no significant correlation with R² < 0.64.22 Further, the Root Mean Square Error (RMSE) was determined serving as a mean error of the linear combination and thus as a measure for the uncertainty of the prediction.5 To evaluate the relationships between the structure and the test parameters of the bitumen, correlation analyses were carried out between the calculated peak areas and the test parameters using the correlation coefficient r according to Bravais and Pearson. In these correlation analyses, the samples were considered depending on the refinery so that the relationships were determined separately for every refinery. Then, the direction of the correlation was compared between the different refineries and patterns were searched. The correlation strength played a minor role in this work because the sample size within the different refinery groups is relatively small. For the statistic evaluation, the software The Unscrambler X10.3 and Microsoft Excel 2010 were used.


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3. RESULTS AND DISCUSSION At first, the results for the description of the penetration are presented. Figure 2 shows the graphical comparison of the measured and the calculated values of this parameter being considered in a logarithmic scale. Regarding this figure, the measured and calculated values agree with each other which is confirmed by the high coefficients of determination with values above 0.85. For the evaluation of the mean error of the linear combination, the RMSE was compared with the reproducibility according to EN 1426. Because the majority of the samples show penetration values below 50 1/10 mm, a permitted deviation of 3 1/10 mm was set and converted in a logarithmic scale to 0.48 1/10 mm being complied by the RMSE of the calibration and the validation. According to these results, the FTIR spectra allow the description and prediction of the penetration. For the further parameters, the results of the PLSR are summarized in Table 3 including the permitted deviation according to the associated standard, the sample number, the number of the PLSR components as well as the mean error RMSE and the coefficient of determination R² for the calibration and the validation. Concerning the softening point TR&B, the mean error of the linear combination is in the same range as the permitted deviation according to the standard whereby, for the calibration, a slight excess can be recognized. However, the coefficients of determination are satisfactory so that an estimation of the softening point based on the FTIR spectra is possible. The phase angle δ considered in two different data sets can also be captured by the FTIR spectra demonstrated by the small mean error and the high coefficients of determination. In principle, the description of the phase angle is very good but, for increasing temperatures from 60°C, the goodness of the linear combinations decreases. The reason for this phenomenon is the


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approximation of the phase angle to a value of 90° because the viscous deformation behavior grows. Therefore, the range of the phase angle decreases with increasing temperature and the differentiation between the samples becomes more difficult. That is the reason why the description of the phase angle is not satisfactory for higher temperatures. As well, for the logarithm of the complex shear modulus |G*|, the mean errors are smaller than the accuracy of the standard and the coefficients of determination exhibit high values. Thus, the complex shear modulus can also be captured by the FTIR spectra. However, a closer look reveals a decreasing goodness of the linear combinations for very low temperatures (DSR method 1, 0°C) and very high temperatures (DSR method 2, 100°C). For the high temperatures, the reason for the lower quality could also be the decreasing range of the complex shear modulus. In contrast, for the lower temperatures, the range of the complex shear modulus grows so that the decreasing quality of the linear combination seems to be caused by further influence factors which cannot be captured with the FTIR spectroscopy. The results concerning the BBR parameters and thus the parameters of the low-temperature range emphasize this assumption because neither the flexural stiffness Sm nor the m value can be captured by the FTIR spectra (see Table 3). This observation was also made for the other loading times of the BBR measurements. A possible explanation for these results could be the growing gel character of the bitumen with decreasing temperatures which is related to increasing interactions between the molecules and the formation of larger molecules. The molecule size exhibits a significant influence on the bitumen properties, especially in the low temperature range.23, 24 According to these results, these increasing interactions and the growing molecule sizes cannot be captured with the FTIR spectroscopy so that the low-temperature behavior of the bitumen cannot be described with the spectra.


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Concerning the chemical parameters, the FTIR spectra allow the description of the asphaltene content wasphaltenes because the mean errors of the linear combinations are below the reproducibility of the standard and the coefficients of determinations are satisfactory (see Table 3). In contrast, the content of the maltene fractions could not be captured with the FTIR spectra demonstrated by the low coefficients of determination, especially for the validation (see Table 3). For the polar compounds, the determined model explains nothing of the variance in the validation data so that no coefficient of determination could be calculated. To evaluate the mean error, the repeatability of the asphaltene separation standard was considered because values for the accuracy of the maltene separation do not exist yet. Thereby, the RMSE exceed the permitted deviation for almost every fraction indicating a large mean error of the linear combinations. As the reason for the unsatisfactory description of the fraction contents, the high structural similarity of the fractions was assumed. According to the presented results, the description and prediction of the penetration, the softening point, the phase angle, the complex shear modulus and the asphaltene content based on the FTIR spectra is possible. However, for the models presented in Figure 2 and Table 3, the necessary number of PLSR components with a value of seven is relatively high. To improve the models concerning the PLSR components, linear combinations were determined separately for every refinery and parameter. In this way, potential influences of refinery related differences in the bitumen structures should be eliminated. For these additional analyses, the separation of the samples in calibration and validation data sets was not possible because of the relatively small sample number within the several refinery groups. Instead, the cross-validation was used to validate the models. The analyses with the separated consideration of the refineries lead to improvements of the goodness of the linear combinations and a smaller number of the necessary


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PLSR compounds in most cases. These results confirm the assumption of the refinery related structure differences affecting the models. Only for the description of the asphaltene content, no significant improvement could be determined, and for the capturing of the softening point, partly deterioration could be recognized because the mean errors excess the permitted deviations. For this reason, it was concluded that the softening point can only be roughly estimated by the FTIR spectra.

In a next step, relationships between the different parameters and the structure of the bitumen concerning the content of different molecules or rather molecule components were investigated. In general, the regression coefficients of the regression function can be used whereby high absolute values of the regression coefficients demonstrate a high influence of the associated variable.17 In the case of the investigated spectra, this approach is limited because, due to the derivative, the input data lose the spectral shape. So, the interpretation of the regression coefficients was very complex. Because of this, instead of the regression coefficients, correlation analyses between the bitumen parameters and the areas of different spectrum peaks were carried out and the direction of the correlations was evaluated. Table 4 summarizes the determined correlation directions for the parameters which could be captured by the FTIR spectra. These correlations are based on all considered bitumen samples in the different ageing states and grades. The arrows upwards symbolize positive correlations while the arrows downwards demonstrate negative relationships. The indicated correlations occur for all or almost all refineries whereby the deviation of only one refinery was permitted. If the correlation directions distinguish for different refineries, no consistent relationship between the parameter and the compounds could be found symbolized by a vertical bar.


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The determined correlations show that the increase of the aromatic and oxygen-containing compounds are associated with a growing asphaltene content as well as an increasing hardness (PEN), viscosity (TR&B), stiffness (log |G*|) and elastic behavior (δ). Further, alteration of the alkene (δ(CH)alkene) and parts of the aromatic structure (δ(CH)arom,896-839 cm-1) can be observed for changes of the asphaltene content and the considered physical parameters. For the further peaks, no consistent correlations could be found to the considered bitumen parameters. But, especially the relationships between the oxygen-containing compounds and the considered parameters are known and demonstrate the significance of the used method and the plausibility of the results. This could be explained with the aging behavior of bitumen. During the aging, bitumen reacts with the oxygen of the atmosphere whereby oxygen is taken up in the form of e.g. carbonyl and sulfoxide compounds. Concerning the physical properties, the aging causes an increasing hardness and stiffness.1-13, 24, 25, 26 In addition to these known relationships, it could be shown that, beside the oxygen-containing compounds, the aromatic and alkene structures also have a crucial influence on the bitumen behavior.

4. CONCLUSION According to the presented results, the FTIR spectroscopy combined with multivariate analysis methods in terms of the PLSR generally allows the description and prediction of various chemical and physical parameters of paving grade bitumen. These parameters include: •

the penetration,

•

the complex shear modulus,

•

the phase angle,

•

the asphaltene content and


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•

the softening point (rough estimation).

Concerning the phase angle, the goodness of the prediction model decreases for temperatures above 50°C because of the increasing viscous behavior of bitumen. This is associated with the approximation of the phase angle to 90° and the reduction of the parameter range between the samples. Regarding the complex shear modulus, a decreasing quality of the model was recognized for very high temperatures (100°C) and very low temperatures (0°C). For the high temperatures, the reduced range of the parameter could again cause the unsatisfactory model. In contrast, in the low-temperature range, influence factors on the stiffness seem to occur which cannot be captured with the FTIR spectroscopy. This assumption is confirmed by the unsatisfactory models for the prediction of the flexural stiffness and the m value of the BBR measurements capturing the lowtemperature behavior of the binder. Further, the content of the maltene fractions could not be captured by the FTIR spectra what is attributed to the high structural similarity between the maltene fractions. Beside the description and prediction of different parameters, relationships between these parameters and the structure of the bitumen could be determined. Increasing aromatic and oxygen-containing compounds are associated with an increasing hardness, viscosity, stiffness and elastic deformation behavior. Further, the structure of the alkene and aromatic compounds changes with the considered parameters. According to these results, the FTIR spectroscopy combined with the multivariate evaluation presents a simple method for a fast characterization of bitumen samples on the one hand. In practice, this method can be used as receiving inspection or fast classification in the bitumen industry, e.g. in the bitumen processing industry or in research institutes. On the other hand, the


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FTIR is suitable to capture the bitumen structure in greater detail allowing the identification of relationships between the structure and the behavior of the binder. Thus, the FTIR spectroscopy is not only a characterization method, but also a method for the investigation and research of bitumen structures. As an outlook, the FTIR based models should be extended by additional parameters, e.g. the dynamic viscosity, the ductility or the solubility. Another interesting approach could be the transfer of the determined models to modified bitumen, especially the widely used polymer modified bitumen, or even the transfer to bitumen mortars or asphalts.


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AUTHOR INFORMATION Corresponding Author Sandra Weigel e-mail: [email protected] Telefon: +49 (0)30 314 72 279 Fax: +49 30 314-72 110 Funding Sources This report is based on parts of a research project carried out at the request of the German Federal Ministry of Transport and Digital Infrastructure, represented by the German Federal Highway Research Institute, under research project No. 7.0249/2011/BRB and on parts of a research project carried out at the request of the German Federal Ministry of Education and Research, represented by The Association of German Engineers, under research project No. 13N13109.

Conflict of Interest The authors declare no competing financial interest.

ACKNOWLEDGMENT The authors would like to thank Professor Dr. Martin Radenberg and Dr. Volker Hirsch for the support and the expert advices. Furthermore, the authors would like to thank Dr. Norbert Simmleit for the provided bitumen samples.


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(25) Valcke, E.; Rorif, F.; Smets, S.: Ageing of Eurobitum bituminised radioavtive waste: An ATR-FTIR spectroscopy study. J Nucl Mater 2009, 393, 175-185 (26) Petersen, J.C.: A dual, sequential mechanism for the oxidation of petroleum asphalts. Pet Sci Technol 1998, 16(9,10), 1023-1059

STANDARDS EN 1426: Bitumen and bituminous binders – Determination of needle penetration, 2007 EN 1427: Bitumen and bituminous binders – Determination of the softening point – Ring and Ball method, 2007 EN 12591: Bitumen and bituminous binders – Specifications for paving grade bitumens, 2009 EN 12607-1: Bitumen and bituminous binders – Determination of the resistance to hardening under the influence of heat and air – Part 1: RTFOT Method, 2007 EN 12607-3: Bitumen and bituminous binders – Determination of the resistance to hardening under the influence of heat and air – Part 3: RFT Method, 2007 EN 14769: Bitumen and bituminous binders – Accelerated long-term ageing conditioning by a Pressure Ageing Vessel (PAV), 2012 EN 14770: Bitumen and bituminous binders – Determination of complex shear modulus and phase angle using a Dynamic Shear Rheomater (DSR), 2012 EN 14771: Bitumen and bituminous binders – Determination of the flexural creep stiffness – Bending Beam Rheometer (BBR), 2012


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Energy & Fuels 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

Page 20 of 26

DIN 51595: Testing of petroleum products – Determination of the content of asphaltenes – Precipitation with heptane, 2000 TL Bitumen-StB: Technische Lieferbedingungen für Straßenbaubitumen und gebrauchsfertige Polymermodifizierte Bitumen, 2007


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Page 21 of 26 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

Energy & Fuels

Tables and Figures Table 1. Conditions of the two different DSR methods DSR method 1 Laboratory 1 32 samples

DSR method 2 Laboratory 2 44 samples

Deformation

γ = 0,5 %

γ = 1,0 %

Frequency

f = 1,59 Hz = 10 rad/s

f = 1,59 Hz = 10 rad/s

Temperature range (steps of 10°C)

0 – 90°C

30 – 100°C

Heating rate

2 K/ minute

5 K/ minute

Setup time for temperature equilibrium on each temperature level

12 minutes

10 minutes

Parallel plate geometry Diameter 8 mm with gap of 2 mm Diameter 25 mm with gap of 1 mm

Unaged samples: 8 mm for 0 to 50°C 25 mm for 30 to 90°C Aged samples: 8 mm for 0 to 50°C 25 mm for 40 to 90°C

Unaged and aged samples: 25 mm for 30 to 100°C

Sample preparation

Heating to 85°C above TR&B, moulding in a silicone mould and storage for 2 to 24 hours

Heating to 180°C, moulding in a silicone mould and measuring immediately after cooling

Table 2. Solvents of the maltene separation with indication of the volume ratio

Fraction

Solvent

saturates

hexane

monoaromatics

hexane/ toluene (24:1)

diaromatics

hexane/ toluene (22:3)

polyaromatics

toluene

polar compounds

toluene/ diethyl ether/ methanol (1:1:3)


21

Energy & Fuels

Table 3. Summary of the results of the PLSR for the description of different bitumen parameters

Parameter

Permitted range according to EN

Calibration

PLSR components

Number of samples

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

Page 22 of 26

RMSE

Validation

R²

RMSE

R²

89.9 %

1.9 K

90.4 %

Physical parameters Conventional parameters TR&K

2K

89

7

2.1 K

DSR method 1 δ0°C

3°

30

7

1.2°

96.4 %

1.3°

94.5 %

δ30°C

3°

32

7

1.5°

97.9 %

1.6°

97.1 %

δ60°C

3°

32

5

2.7°

85.4 %

2.7°

69.0 %

δ90°C

3°

32

3

1.9°

43.2 %

0.9°

47.8 %

log |G*|0°C

15 % ≙ 1.2 Pa

30

7

0.039 Pa

93.3 %

0.087 Pa

60.1 %

log |G*|30°C

15 % ≙ 0.9 Pa

32

7

0.074 Pa

97.1 %

0.129 Pa

90.1 %

log |G*|60°C

15 % ≙ 0.6 Pa

32

7

0.081 Pa

97.4 %

0.115 Pa

93.1 %

log |G*|90°C

15 % ≙ 0.4 Pa

32

7

0.077 Pa

96.8 %

0.098 Pa

92.1 %

DSR method 2 δ30°C

3°

44

6

1.3°

97.4 %

1.7°

95.5%

δ60°C

3°

44

6

1.2°

94.1 %

2.0°

75.6 %

δ100°C

3°

44

7

0.6°

77.4 %

0.6°

69.3 %

log |G*|30°C

15 % ≙ 0.8 Pa

44

5

0.065 Pa

96.3 %

0.094 Pa

89.9 %

log |G*|60°C

15 % ≙ 0.6 Pa

44

5

0.081 Pa

95.7 %

0.114 Pa

87.7 %

log |G*|100°C

15 % ≙ 0.3 Pa

44

5

0.064 Pa

94.2 %

0.099 Pa

75.1 %

BBR Sm, -16°C, 60s m-16°C, 60s

27 % ≙ 60 MPa

49

7

21.7 MPa

83.6 %

70.6 MPa

49.8 %

13 % ≙ 0.042

49

7

0.030

75.3 %

0.044

49.8%

92.4 %

1.30 wt %

86.0 %

Chemical parameters wasphaltenes

15 % ≙ 1.95 wt %

89

7

1.03 wt %

Column chromatography wsaturates

10 % ≙ 1.17 wt %

32

7

0.71 wt %

92.9 %

1.51 wt %

51.3 %

wmonoaromatics

10 % ≙ 0.65 wt %

32

7

0.35 wt %

81.5 %

0.96 wt %

40.5 %

wdiaromatics

10 % ≙ 0.43 wt %

32

6

0.16 wt %

85.9 %

0.54 wt %

11.3 %

wpolyaromatics

10 % ≙2.04 wt %

32

5

1.41 wt %

73.6 %

1.72 wt %

65.5 %

wpolarcompounds

10 % ≙3.29 wt %

32

5

1.42 wt %

86.5 %

4.79 wt %

/


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Page 23 of 26

Table 4. Direction of the correlations between different chemical compounds and various characteristic parameters of bitumen PEN

TR&B

log |G*|

δ

wasphaltenes

Aliphatics ν, δ(CH3)

-

-

-

-

-

ν, δ(CH3)

-

-

-

-

-

δ(CH)alkene

↑

↓

↓

↑

↓

Aromatics ν(C=C)arom

↓

↑

↑

↓

↑

δ(CH)arom,896-839 cm-1

↑

↓

↓

↑

↓


-

-

-

-

-


-

-

-

-

-

Oxygen-containing compounds ν(OH)

↓

↑

↑

↓

↑

ν(C=O)

↓

↑

↑

↓

↑

ν(S=O)

↓

↑

↑

↓

↑

5 δs(CH2), δas(CH3)

νas(CH2)

4

2,946 - 2,880 cm-1

1,485 - 1,400 cm-1

νs(CH3)

2,876 - 2,864 cm-1

3

Absorbance [-]

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

Energy & Fuels

νs(CH2)

δs(CH3) 1,400 - 1,357 cm-1

2,864 - 2,800 cm-1

2

δ(-(CH2)n-) 734 - 707 cm-1

νas(CH3) 2,965 - 2,946 cm-1

1 δ(CH)alkenes 983 - 925 cm-1

ν(C=C)arom

0

1,637 - 1,547 cm-1

ν(OH)

ν(S=O)

3,400 - 3,120 cm-1

-1

δ(CH)arom

ν(C=O)

896 - 839 cm-1 839 - 786 cm-1

1,730 - 1,670 cm-1

777 - 734 cm-1

1,070 - 983 cm-1

-2 3.500

3.000

2.500

1.500

1.000

-1

Wave number [cm ]

Figure 1. Definition of the peaks and integration limits for the calculation of the peak areas of the FTIR spectra3, 4, 8, 18-20


23

Energy & Fuels

2,1

log PENcalculated [1/10 mm]

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

Page 24 of 26

1,8

1,5

1,2

0,9

Calibration RMSE = 0.067 1/10 mm R² = 0.92% Validation RMSE = 0.077 1/10 mm R² = 0.86%

0,6

0,3 0,3

0,6

0,9

1,2

1,5

1,8

2,1

log PENmeasured [1/10 mm]

Figure 2. Comparison of the measured and the calculated values of the logarithm of the penetration PEN (7 PLSR components)


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Page 25 of 26 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

Energy & Fuels

Definition of the peaks and integration limits for the calculation of the peak areas of the FTIR spectra 277x176mm (300 x 300 DPI)


Energy & Fuels 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

Comparison of the measured and the calculated values of the logarithm of the penetration PEN (7 PLSR components) 183x183mm (300 x 300 DPI)


Page 26 of 26

Bitumen Characterization with Fourier Transform Infrared

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