Rheological and chemical properties of field aged binders and their variation within the wearing course

Figures & data

Figure 1. Overview of the pavement sites, including the service life in years (y).

Table 1. Information of the field sections: original binder, pavement age and mix type.

Country and code	Original binder type, penetration, dmm	Field age, years	Mix type
FR1	3.9% 50/70 + 1.4% RA + 0.4% Warm mix asphalt additive	8	Thin AC 0/10
CZ	PmB 45/80-50, pen 69	10	SMA 11S
FR2	PmB 25/55-65, pen 51	15	Thin AC 0/10
HR	50/70, pen 64	21	AC 11
DK1	PmB 40/100-75, pen 64	8	SMA 11
DK2	70/100+ CR pen 42	8	SMA 11
DK3	70/100+ CR pen 47	8	SMA 11
BE	PmB 50/85-50, pen 64	10	SMA 0/6.3
UK	PmB 45/80-65	8	Airfield Asphalt 0/14
HU1	PmB 30/60S	18	SMA 12
HU2	PmB 30/60S	18	SMA 12
IRL	Unmodified	16	HRA 20
FR3	PmB	21	Thin AC 0/10
MA	20/30	8.5	AC 0/14
FR4		21	AC 0/10

Figure 2. Schematic of the slicing and some photographs of the slices before recovery.

Table 2. Void contents, thickness wearing course, binder content and number of separately recovered slices for each section.

Country and code	Void content % (min.-max.)	Thickness wearing course, cm (min.-max.)	Binder content %	No. of slices
FR1	12.3 (10.2-16.4)	35 (28-40)	4.8	3
CZ	7.1 (5.3-8.1)	40 (39-40)	5.9	4
FR2	6.8 (4.6-11.6)	28 (23-31)	5.5	3
HR	2.5 (2.4-2.6)	47 (46-49)	6.3	3
DK1	3.9 (2.1-5.9)	30 (25-34)	5.6	2
DK2	4.0 (1.1-7.5)	24 (21-26)	5.6	2
DK3	5.0 (1.7-7.9)	24 (21-29)	5.7	2
BE	6.1 (5.7-7.2)	28 (26-30)	6.0	2
UK	5.8 (4.4-8.0)	48 (44-52)	5.2	5
HU1	3.1 (3.0-3.3)	45 (44-47)	7.1	5
HU2	3.3 (3.1-3.5)	41 (41-42)	6.1	4
IRL	6.5 (4.8-8.1)	43 (42-44)	6.3	3
FR3	9.1 (7.3-12.1)	24 (21-28)	5.5	3
MA	7.0 (6.0-9.2)	60 (51-65)	4.7	3
FR4	–	–	4.5	1

Figure 3. An example of FTIR spectra, peak integrations and the calculation of indices.

Table 3. Example of the repeatability of the FTIR indices for one site.

IC = O	Average	SD	COV, %
HU2-S1	0.115	0.001	1.2
HU2-S2	0.023	0.003	11.5
HU2-S3	0.007	0.002	32.0
HU2-S4	0.040	0.001	3.6
IS = O	average	SD	COV, %
HU2-S1	0.146	0.003	1.7
HU2-S2	0.094	0.001	1.6
HU2-S3	0.072	0.004	4.9
HU2-S4	0.117	0.001	0.5
IPB	Average	SD	COV, %
HU2-S1	0.022	4.E−04	1.6
HU2-S2	0.027	3.E−04	1.1
HU2-S3	0.029	4.E−04	1.4
HU2-S4	0.026	7.E−05	0.3
IPS	average	SD	COV, %
HU2-S1	0.026	0.001	4.4
HU2-S2	0.024	0.001	3.6
HU2-S3	0.024	4.E−04	1.7
HU2-S4	0.024	0.001	2.7

Figure 4. Illustration of the selection of strain levels for two binders.

Table 4. Parameters calculated by the Rhea software (beta version 4) (Abatech).

Parameter	Description
Glover – Rowe (G-R)	G-R was calculated from the G* and phase angle (δ) values at 15°C and 0.005 rad/s. These G* and δ values were derived from a master curve based on 8 mm plate data with a reference temperature of 15°C. $G-Rparameter={\displaystyle \frac{G\ast {(\cos \mathrm{\partial })}^2}{\sin \mathrm{\partial }}}$
LSTDSR LmTDSR	The limiting stiffness temperature (LST) and limiting m temperature (LmT) were determined from master curves constructed with 4 and 8 mm data. When calculating G(60 s) and m(60 s) at a certain temperature, the reference temperature was set to this temperature, and only four isotherms, the one at the temperature of interest, and three tested above this temperature were used. Data of G(60 s) and m(60 s) were determined at temperature intervals of 6°C. LST and LmT were determined according to ASTM D7643-16, LST as the temperature where G(t) is 143 MPa and LmT as the temperature where m = 0.275, in correspondence to (Hajj et al., 2019; Reinke et al., 2016).
ΔTc DSR	LSTDSR – LmTDSR
Crossover parameters (CR)	Crossover parameters were determined from the master curves constructed with 4 and 8 mm plate tests, reference temperature 0°C: The CR- frequency was calculated using the Christensen–Anderson model, and the CR-temperature and stiffness were calculated at a frequency of 10 rad/s.
R-index	Calculated using log (1 GPa/the crossover stiffness)
Pen.cal..	A penetration was calculated based on G* at 25°C and 0.4 Hz: logG*(MPa) = 2.923–1.9 * log(pen) (Saal & Labout, 1958; Heerden et al., 2011)

Figure 5. Carbonyl index of all slices.

Figure 6. Butadiene and styrene indices for all slices.

Figure 7. SARA fractions of top and bottom slice, only some sections are shown.

Figure 8. Relations between SARA fractions and carbonyl index.

Figure 9. Black plots, left, and frequency sweeps at 50°C, right, of all slices derived from the HR and the HU2 section.

Figure 10. Calculated penetration at 25°C for all sections and all slices. The penetration of the original binder is added, if known.

Figure 11. G-R for all sections and all slices.

Figure 12. LST_DSR versus LmT_DSR for selected pavement sites (vertical error bars are equal to the symbol size).

Table 5. Overview of a two-variable linear regression analysis: Pearson’s correlation coefficients (r) are plotted (only r values ≥0.8 and ≤−0.8 are shown).

	IC=O	IS=O	Pen.cal	LSTDSR	LmTDSR	ΔTc DSR	Log (G-R)	Log(CRFreq.)	CRTemp.	R-index	δ@1MPa
IC=O	1.00
IS=O	0.80	1.00
Pen.cal	−0.88	−0.90	1.00
LSTDSR		0.83	−0.85	1.00
LmTDSR	0.83	0.89	−0.93	0.94	1.00
ΔTcDSR						1.00
Log (G-R)	0.87	0.82	−0.87	0.82	0.93		1.00
Log(CRFreq.)	−0.87	−0.83	0.87	−0.81	−0.94		−0.98	1.00
CRTemp.	0.89	0.84	−0.88		0.91		0.98	−0.98	1.00
R-index										1.00
δ @1MPa										−0.91	1.00

Figure 13. Comparison of carbonyl indices of reference binders after RTFOT + PAV to field-aged top slices.

Figure 14. Phase angle versus G* at 0.005 rad/s and 15°C, representing top and bottom slices and reference binders, before and after laboratory ageing.

Figure 15. Phase angle versus G* at 0.005 rad/s and 15°C, including aged bottom slices.

Figure 16. LST_DSR versus LmT_DSR, including the aged bottom slices.

Figure 17. Difference in carbonyl index of top and second slice versus the void content of the surface layer. Error bars for the void content are equal to the variation in void contents of the individual cores. For ΔI_C = O the absolute error on I_C = O is doubled.

Hajj, R., Filonzi, A., & Bhasin, A. (2019). TECHNICAL REPORT 0-6925-1, Improving the Performance-Graded Asphalt Binder Specification: Final Report, http://library.ctr.utexas.edu/ctr-publications/0-6925-1.pdf

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